FR2759225A1 - Symbol circulation device especially for facsimile - Google Patents

Abstract

. The emitter has a selector part (155) which selects a ratio among a number of available values of the number of redundant information symbols which might allow for the correction of errors to the number of primary information symbols corresponding to the redundant symbols. The number of redundant symbols is determined (615) from the selected ratio and the symbols are emitted (103, 151). The ratio increases as the quality of transmission decreases, and the number of redundant symbols is always greater than that needed to correct the previous emission of symbols. Protocol information is inserted (152) into the transmission to give the initial reception mode protocols and to interrupt reception.

Description

 The present invention relates to a method and an information symbol broadcasting device and to a method and an information symbol receiving device.

 It applies in particular to the dissemination of data, sounds, texts, graphics, faxes and images, possibly intended to be displayed or printed, on different transmission media, and, more particularly, to the transmission simultaneously with several reception means.

 Transmission, which is the step between transmission and reception, is linked to the transmission medium. Broadcasting is the transmission between a transmitter and at least one receiver, and in general several receivers.

 Currently known facsimile transmission systems use the switched telephone network for sending well-known facsimile signals. The implementation of these systems remains very expensive because of the sequential operations it involves to perform pseudo-diffusion, each transmission to a receiver being performed individually.

 Radio broadcast experiments of facsimile signals have been attempted, using an adapter that demodulates the radio signals to convert them to a facsimile signal. Document US-5,299,024 CONSTANZA is known, for example, which describes an information diffusion system via an electronic module which on the one hand captures radio signals and, on the other hand, simulates a duplex communication with a fax machine to allow unidirectional transfer of information.

 Such systems have many disadvantages. Duplex communication simulation takes the fax machine uptime and adds to the process. Finally, the electronic module must have a high capacity memory in order to temporarily store the information received before transmitting it to the fax machine.

 We also know the dissemination of data, teletext type, whose operating principle is very different from that of faxing. The format of the video signal now allows the dissemination of alphanumeric data, intended to be displayed on a television screen, but is not suitable for the burst transmission of large volume of data, does not allow the transmission of a high instantaneous data throughput, or the transmission of other types of data.

 None of these systems allows the dissemination of data with addressing, individual or group, receiving devices.

Conventional fax transmission is according to ITU-T Recommendation T.30 (initials of the English name "International
Telecommunication Union "), which deals with the procedures for transmitting facsimile documents over the switched telephone network using a standard protocol involving bidirectional exchanges.

This method of transmission is perfectly suited to image transport on the one hand and point-to-point exchanges on the other.

 FIG. 1 generally illustrates the exchanges of frames intervening during the transmission of two pages, between the transmitting fax machine and the receiving fax machine. The format of the frames used is illustrated in FIG.

 For all these systems, the error correction is known, by digital information processing. An error correction device is, it is recalled, intended to overcome the random transmission defects that induce errors in the information received. However, these currently known error corrections do not make it possible to react to fluctuations in the characteristics of the transmission medium.

 However, broadcast transmission media with frequency modulation or radio transmission of television signals can offer transmission quality that varies over time.

 FIG. 3 illustrates a standard format in the so-called "HDLC" format, which corresponds to a family of advanced protocols operating in synchronous mode according to a specific frame format. It is this frame format that has been adopted for the transmission of digital signals in fax.

 This frame is described in the aforementioned T30 recommendation. In addition, the exchanges of frames illustrated in Figure 1 are in error correction mode called "ECM". The error correction method, commonly referred to as "ECM", based on an acknowledgment signal issued by the receiver, requires bidirectional exchanges between the transmitting and the receiving facsimile apparatus, so that the receiving facsimile can request retransmission of he did not receive correctly. FIG. 2 illustrates an exemplary page transmission sequence according to this protocol.

 The main disadvantage of this method is that it can not allow the use of this data format for broadcast faxes, since bidirectional exchanges must take place.

 The main purpose of the invention is to propose a method and a device for broadcasting data. It aims, in the first place, that the errors affecting the information received by the reception devices can be corrected without, however, that the rate of useful information is too limited by the redundancies transmitted. It also aims to enable each receiving device to determine whether, on the one hand, the information is intended for it and, on the other hand, whether the information is of interest to its user.

It also aims that reception devices can operate asynchronously, based on errors affecting the information they receive, and information that is intended for them or that interest their users. It furthermore aims that, when the transmission quality of a transmission medium is excellent, the instantaneous bit rate of useful information is maximum and that this quality is reduced, the number of redundancies transmitted is sufficient to ensure the correction. transmission errors.

 Another object of the invention is: to implement a method and devices for broadcasting a facsimile; - to adapt the error correction to the instantaneous effective conditions of transmission - to guarantee a good quality of reception of faxes broadcast - to allow the integration of a fax transmission device broadcast in a conventional fax machine, that is to say that is, of known and commonly used type; - to allow the integration of a fax reception device broadcast in a conventional fax machine - to use the resources of conventional fax machines to make the fax broadcast, to reduce the additional costs by sharing as much resources as possible Commons; - Use the fax transmission protocol on different broadcast media, that is to say to propose a broadcasting system independent of the broadcast medium; - to use the fax transmission protocol for other types of data to be broadcast, the transmission being guaranteed without loss of data - to allow the implementation of a simplex process in conventional faxing and - to allow to modify dynamically the transmission parameters according to the evolution of the quality of the transmission medium to obtain the permanent adaptability of the system.

According to a first aspect, the invention aims, for this purpose, a device for broadcasting primary information symbols representing a physical quantity, via a transmission medium, symbols likely to be received simultaneously by a plurality of reception devices, broadcasting device characterized in that - it takes into account:
an estimate of transmission quality on the medium of
transmission and
a ratio of a number of information symbols of
redundancy, likely to allow the correction of errors
assigning primary information symbols, on the number
of primary information symbols corresponding to the
redundancy information symbols, and - it comprises:
ratio selecting means adapted to implement
predetermined "ratio selection" rules taking into
counts a transmission quality estimate on said
transmission medium, to select said ratio among
a plurality of ratio values,
means for determining information symbols of
redundancy whose number corresponds to the selected ratio,
and
means for transmitting the primary information symbols and
redundancy information symbols.

Correlatively, according to a second aspect, the invention aims to
i) a device for receiving primary information symbols representing a physical quantity, transmitted via a transmission medium by a broadcasting device, and capable of being received simultaneously by a plurality of reception devices, device receiver having a symbol receiving means from the broadcasting device, and characterized in that - it takes into account a ratio of a number of redundancy information symbols transmitted by the broadcasting device and capable of enabling the correction of errors affecting primary information symbols, with respect to the number of primary information symbols corresponding to these redundancy information symbols, and - it comprises:
. extraction means, among the symbols received by the means
reception, a ratio selected by the
diffusion, and
error correction means affecting symbols
of primary information adapted to implement a number
of redundancy information symbols less than or equal to
number corresponding to the selected ratio, to correct
errors affecting primary information symbols.
ii) a primary information symbol receiving device representing a physical quantity, transmitted via a transmission medium by a broadcasting device, and received via a symbol receiving means from of the broadcasting device, receiving device characterized in that: - it takes into account a ratio of a number of redundancy information symbols transmitted by the broadcasting device and capable of enabling the correction of errors affecting symbols of primary information, in relation to the number of primary information symbols corresponding to these redundancy information symbols, and - it comprises:
extraction means, among the symbols received by the means
reception, a ratio selected by the
diffusion, and
error correction means affecting symbols
of primary information adapted to implement a number
of redundancy information symbols less than or equal to
number corresponding to the selected ratio, to correct
errors affecting primary information symbols.

Correlatively, according to a third aspect, the invention relates to a method of broadcasting primary information symbols representing a physical quantity, via a transmission medium, symbols that can be received simultaneously by a plurality of communication devices. reception, characterized in that: - it takes into account:
an estimate of transmission quality on the medium of
transmission and
a ratio of a number of information symbols of
redundancy, likely to allow the correction of errors
assigning primary information symbols, on the number
of primary information symbols corresponding to the
redundancy information symbols, and - it comprises:
. a ratio selection stage during which we put in
implement rules called "ratio selection" predetermined
taking into account a transmission quality estimate
on said transmission medium, to select said ratio
among a plurality of ratio values,
a step of determining information symbols of
redundancy during which symbols are determined
redundancy information the number of which corresponds to
ratio selected, and
a step of transmitting the primary information symbols and
redundancy information symbols.

Correlatively, according to a fourth aspect, the invention relates to a method of receiving primary information symbols representing a physical quantity, transmitted via a transmission medium by a broadcasting device, and capable of being received simultaneously. by a plurality of reception devices, the method comprising a step of receiving symbols from the broadcasting device, and being characterized in that: - it takes into account a ratio of a number of redundancy information symbols transmitted by the broadcasting device and capable of allowing the correction of errors affecting primary information symbols, with respect to the number of primary information symbols corresponding to these redundancy information symbols, and - it comprises:
a ratio extraction step, during which one extracts,
among the symbols received during the receiving step
a ratio selected by the broadcasting device, and
an error correction step, during which one
correct errors affecting information symbols
primary school, during which a number of
redundancy information symbols less than or equal to
number corresponding to the selected ratio, to correct
errors affecting primary information symbols.

 Thanks to these arrangements, when the transmission quality increases, the broadcasting device can take this into account and reduce the ratio of the number of redundancy information symbols to the number of image information symbols so that the duration and therefore the cost of transmission decreases, without risk of error. On the other hand, when the quality of transmission decreases, the broadcasting device can take this into account to increase said ratio so that, although the duration and the cost of the transmission increase, the quality of the transmission remains assured.

 The invention thus makes it possible to implement a variable return error correction primary information symbol diffusion procedure, said output corresponding in fact to the quality of the transmission.

 The invention also makes it possible to optimize the delay and the cost of each transmission by optimizing the instantaneous redundancy information symbol rate used.

 The synchronization of the possible reception devices of the primary information symbols is carried out by each of them, without the broadcasting device having to wait for or process any information coming from a reception device.

 Thanks to these arrangements, the broadcast device performs only one broadcast of each block of primary information symbols and redundancies through a transmission medium common to several receiving devices. The implementation of systems using this method can be performed at a very low cost, by using a low bit rate broadcast network, the facsimile receiving devices being able to operate as in the prior art, ie say with print speeds identical to those of known type fax machines.

 The bandwidth of the transmission medium is therefore used optimally because it avoids both: the time taken by the responses of the reception devices, the multiple broadcasts of the same information, the symbol transmission delays redundancy information that would be excessive, and - the delays of a second issue that would be consecutive to a weakness in the number of redundancy information symbols.

 However, it is noted that the repetition of the broadcast of symbol sequences, for example of protocol, can be used but that the distribution of redundancy information symbols makes it possible to avoid that this repetition relates to the primary information symbols.

 The invention also makes it easy to integrate a fax reception device broadcast in a known type of fax reception device, and therefore to realize at a lower cost a broadcast facsimile reception device, the correction of the fax reception device. error using procedures and components similar to those implemented in the Error Correction Mode ("ECM") of facsimile machines.

 It is noted that the implementation of the method can be done on different wired and wireless transmission media, in phase, amplitude, and frequency modulation, in quadrature amplitude and phase modulation, on radio carriers. , television, for example.

 The creation of an image information symbol broadcasting service reserved for customers, correspondents or subscribers, such as, for example, the dissemination of general or thematic information, can then be envisaged. The broadcast device then broadcasts the image information symbols through a common transmission medium to a plurality of receiving devices.

 The invention also allows the transmission of data or image information symbols in simplex, that is to say with all the signals transmitted by a transmission device to at least one receiving device.

 According to particular characteristics of the broadcasting device as succinctly set forth above, the predetermined ratio selection rules comprise: the rule according to which the number of redundancy information symbols transmitted increases when the estimated transmission quality decreases, or the rule according to which the number of redundancy information symbols is always greater than what would have been necessary to correct the transmission errors of the previous diffusion of information symbols.

 By virtue of each of these arrangements, the transmission error correction capability and the performance are correlated with the estimated quality of the transmission so that the image information symbols have little risk of being lost and that the speed of transmission is optimized.

 According to particular features, the broadcasting device as briefly described above comprises an insertion means adapted to insert, among information symbols to be transmitted, protocol symbols corresponding to lines of information symbols. in said block.

 Correlatively, the primary information symbol broadcasting device inserting, among transmitted protocol symbols, successive line numbers corresponding to lines of information symbols in a block, the receiving device, as briefly described below. above, comprises a transmission quality estimation means adapted to detect the absence of line numbers in the received information symbols.

 Correlatively, the method of broadcasting information symbols as briefly described above comprises an insertion step during which information symbols to be transmitted are inserted into line number protocol symbols. successive corresponding to lines of information symbols in said block.

 Correlatively, the primary information symbol broadcasting device inserting, among transmitted protocol symbols, successive line numbers corresponding to lines of information symbols in a block, the reception method, as succinctly explained below. above, comprises a transmission quality estimation step, during which the absence of line numbers in the received information symbols is detected.

 Thanks to these arrangements, when at least one line is lost by the transmission, the receiving device can detect the absence of this line, without using redundancy information symbols.

 According to particular features, the diffusion device, as briefly described above, comprises a repetition means adapted to repeat sequences of symbols and is adapted to increase the number of repetitions performed by the repeating means when the quality the transmission means being adapted to transmit each sequence of symbols repeated by said repeating means.

 Correlatively, the diffusion method, as succinctly set forth above, comprises a repetition step, during which symbol sequences are repeated and the number of repetitions performed during the repetition step is increased when the The transmission quality estimated during the quality estimation step decreases, each sequence of repeated symbols being transmitted during the transmitting step.

 Thanks to these arrangements, when the transmission quality increases, the broadcasting device can take this into account and reduce the number of repetitions of information symbol sequences so that the duration and therefore the cost of transmission decrease, without risk. error. On the other hand, when the transmission quality decreases, the broadcasting device can take this into account in order to increase said number of repetitions in such a way that, although the duration and the cost of the transmission increase, the quality of the transmission remains assured.

 According to particular features, the broadcasting device, as briefly described above, comprises: reception means adapted to receive from at least one said reception device, symbols received by said reception device, and means for estimating the number of errors affecting primary information symbols received by said receiving means adapted to provide a transmission quality estimate on said transmission medium, said ratio selecting means being adapted to take into account said quality estimate.

 Correlatively, the broadcasting method, as succinctly described above, comprises: a reception step during which, from at least one said reception device, symbols received by said reception device are received, and a step of estimating a number of errors, during which the number of errors affecting primary information symbols received during the receiving step, during which an estimate of transmission quality on said transmission medium, said quality estimate being taken into account during the ratio selection step.

 Thanks to these provisions, the broadcasting device can estimate the quality of transmission, without the need for information symbol processing in the reception device.

 Correlatively, the receiving device, as briefly described above, comprises: a transmission quality estimation means adapted to provide an estimate of transmission quality on said transmission medium and a transmission means adapted to transmitting, to said broadcasting device, a signal representative of said transmission quality.

 Correlatively, the reception method, as briefly described above, comprises: a quality estimation step, during which a quality of transmission is estimated on said transmission medium and a transmission step, at during which a signal representative of said transmission quality is sent to said broadcasting device.

 Thanks to these arrangements, the receiving device can estimate the quality of transmission, without the need for information symbol processing in the broadcasting device.

 According to particular features, the broadcasting device, as briefly described above, comprises receiving means adapted to receive from at least one said reception device, information symbols representative of a quality estimate of transmission on said transmission medium, the ratio selecting means being adapted to take into account said quality estimate.

 Thanks to these arrangements, the duration of the signal transmission from the receiving device to the transmitting device is minimal, which reduces the waiting time and the cost of transmission.

 The invention also relates to a network characterized in that it comprises a transmission medium, a primary information symbol broadcasting device as succinctly set forth above and at least one primary information symbol receiving device such as Briefly explained above, the selected ratio extracted by the extraction means of the receiving device is the ratio selected by the selection means of the broadcasting device.

 The invention also relates to a fax machine characterized in that it comprises a primary information symbol receiving device as succinctly explained above.

 The advantages of this network and this fax are identical to those of the devices as briefly described above, they are not recalled here.

 Other advantages, aims and features of the present invention will appear on reading the description which follows, made with reference to the accompanying drawings for an explanatory and non-limiting purpose, in which - Figure 1 shows a succession of signals exchanged between a facsimile transmitter and receiver, in accordance with ITOU recommendation T.30 well known in the field of facsimile machines; - Figure 2 shows a succession of signals exchanged between a transmitter and a facsimile receiver, in a correction mode error, according to the protocol presented in Figure 1, in an example of transmission of two pages of a document; FIG. 3 represents a temporal structure of a signal, or frame, containing primary image information symbols, in accordance with the protocol presented in FIG. 1; FIG. 4 represents a time structure comprising several frames illustrating the transmission; two multiplexed, or interleaved, broadcast procedures; FIG. 5 represents a temporal structure of a start-up signal or "frame" implemented with the present invention; FIG. 6 represents a time structure of a signal, or frame, representative of the end of a transmitted symbol block, in accordance with the protocol presented in FIG. 1; FIG. 7 represents a temporal structure of a signal, or frame, representative of the end of a transmitted block of symbols, implemented with the present invention; FIG. 8 represents a time structure of a set of frames illustrating the aforementioned ECM error correction mode implementing the protocol presented in FIG. 1; FIG. 9 represents a time structure of a set of frames illustrating the error correction implemented with the present invention; FIG. 10 is a representation of a block distribution of the symbols to be transmitted, implementing the protocol presented in FIG. 1; FIG. 11 is a representation of a block distribution of the symbols to be transmitted, implemented with the present invention; FIGS. 12, 13 and 14 represent three successions of signals, or frames, of startup implemented with the present invention; in three different modes of operation - Figure 15 shows a time structure of a set of address frames for individual addressing of receiving devices implemented with the present invention - Figure 16 shows a time structure of a so-called "newly tuned" remote receiver management control signal, or frame, implemented with the present invention; FIG. 17 represents a temporal structure of a signal, or frame, of a management control of remote receiver called "old right removed", implemented with the present invention - Figure 18 shows a succession of transmitted signals, in combination with the setting e Embodiment of the present invention - Figures 19 and 20 show three successions of transmitted signals, in combination with the practice of the present invention; FIG. 21 represents image communication devices implemented with the present invention; FIG. 22 represents a block diagram of a receiver-specific electronic circuit shown in FIG. 21; FIG. 23 represents a block diagram. an electronic circuit specific to a transmitter shown in Figure 21; FIG. 24 represents the organization of tasks performed by or in cooperation with the circuit shown in FIG. 22; FIG. 25 represents the organization of tasks performed by or in cooperation with the circuit shown in FIG. 23; FIGS. 26, 27 and 29 show partial operating diagrams of a reception communication control means implemented with the present invention; FIG. 28 represents an operating flow chart of a quality control means at Within the transmission device implemented with the present invention - Figure 30 shows an operating flow chart of a page control means received within a receiving device implemented with the present invention - Figure 31 represents an operating flowchart of a frame flow control and synchronization means, within a receiving device, implemented with the present invention - Figs. 32 and 33 show partial flowcharts of operation of a document selection means, within a reception device, implemented with the present invention - FIG. 34 represents a partial flowchart operation of the transmission communication device; FIG. 35 represents the information symbols to be transmitted, in the form of blocks implemented with the present invention; FIG. 36 represents the received information symbols corresponding to the symbols represented in FIG. 35, in the form of blocks; FIGS. 37 and 38 show data structures stored in device memories implemented with the present invention; FIGS. 39, 40 and 41 are flowcharts showing the operation of the means used both by means of coding means and decoding means implemented with the present invention.

DEFINITIONS
Throughout the description is called: - information or symbol of primary information, the set of symbols, or data, of a "message", that is to say the strict useful part of the signals emitted, is also the part of the signals strictly representative of the image transmitted, possibly in compressed form, - information or symbol of secondary information, the set of symbols, or data, of a "message" received, that is to say the part of the signals received which corresponds to the primary information symbols transmitted, or also the part of the signals strictly representative of the received image, possibly in compressed form, - redundancy or redundancy information symbol, symbols capable of allowing the correction of error affecting information, - coding, determination of redundancy information symbols, - decoding of symbol correction using redundancy information symbols, - transmitter, transmitting fax machine, broadcast device or transmission device, a device which is adapted to transmit a message, even if, during the transmission, it receives signals, for example protocol, - receiver, receiving fax machine, receiving device, a device which is adapted to receive a message, even if, during reception, it transmits signals, for example protocol, - address, identifier or address information symbol, symbols capable of allowing each receiving device determine whether or not the information associated with that address is to be processed by him; - "frame" means a digital signal comprising fields each having a predetermined meaning as a function of their position in the frame and - "transmission", transmission via a transmission medium of signals representative of data or symbols, - "reception", the reception by means of a transmission medium of representative signals of data or symbols, - "transmission", the whole of a transmission and a corresponding reception and - "broadcast procedure" means a set of symbols intended for the same receiving device (s) and corresponding to a coherent primary information coming from the same source.

DESCRIPTION OF A PARTICULAR EMBODIMENT
THE INVENTION ADAPTS TO TELEPHONE TRANSMISSIONS
The communication method described and shown is based on a structuring of the signals to be transmitted as a frame, the format of which is illustrated in FIGS. 1 and 3. This frame format is that of the frames used for the transmission of facsimile which is well known to the human being. job. These frames are characterized by a division into fields each having a different meaning and a corresponding interpretation by the device for receiving and processing the communication.

 In Figure 1 are shown horizontal arrows going, in one direction or the other, the fax machine transmitter on the left to the receiving fax on the right, and vice versa. Each of these arrows represents a signal transmitted in the direction of the said arrow, the chronological order of the signals being that of the successive arrows represented from top to bottom - in a first phase, called "A", the emitting fax machine transmits to the fax machine receiving a ringing tone, then a signal referenced "CNG", by which the transmitter identifies itself as a data processing terminal.

In return, the receiver sends a signal referenced "CED" which indicates its presence near the transmitter, - in a second phase, called pre-message phase "B", the receiving fax transmits a signal referenced "DIS" which describes its characteristics, such as the number of data it can process per second.

Then, possibly, it sends a signal referenced under the name "NSF" (initials of the English words used by the person skilled in the art: "Non Standard Facilities") which enables him to inform the transmitting device that he is capable of to carry out particular treatments, in harmony with this emission device. The receiving device receives, in return, a signal referenced as "NSS", in response to the "NSF" signal. Finally, the transmission device transmits a signal referenced under the name "TCF", capable of allowing the estimation of a transmission quality of the transmission medium. Finally, the receiving device sends a signal referenced "CFR" which indicates the smooth running of phase B, - in phases "C", the transmitting fax machine sends signals referenced "FCD, XXX" where XXX corresponds to a number which is initially equal to 000 and then, at each signal, is incremented by one unit, and represents a part of the image to be transmitted and, in error correction mode, redundancies intended to detect and correct any transmission errors. information with which they are transmitted in said signal. Then the transmitter sends a signal referenced "RCP" which delimits a block of signals, - in the phases "D", if it is in error correction mode, the sending fax machine sends a signal referenced "PPS-NULL" page, block, the number of frames that identifies the end of a block of signals. Then, still in error correction mode, the receiver sends a signal referenced "PPR" if there is an error and "MCF" otherwise, which identifies the "FCD" frames that are missing on reception. "C" and "D" type phases follow each other, as long as there is data to be transmitted and - after the last of the "D" phases, during the phase called "E", the transmitting fax machine transmits a signal referenced "DCN" which indicates that all the information he had to transmit was transmitted.

 In an example corresponding to the transmission of two pages of a document in error correction mode, the succession of signals exchanged between the transmitter and the facsimile receiver, according to this protocol is presented in FIG.

 FIG. 2 shows the same signal successions as in FIG. 1, in the case of transmission error then of receiver availability fault, the thickest arrows being those corresponding to a higher instantaneous data rate, typically 14400 bits per second (commonly referred to by their initials "bps"), the finest arrows typically corresponding to 300 bps. For example, the first, fourth and seventh arrows correspond to "C" phases of FIG. 1, while the second and third arrows correspond to a "D" phase in FIG.

 FIG. 3 represents, on a banner representing the information transmitted successively, the temporal structure of the transmission of a facsimile the information is transmitted in a succession of fields - a field F 1 of frame separator commonly called a flag allowing to identify the beginning, here, and the end, see below, of a frame - an address field A 2 of the frame which contains eight bits, especially in the case of the facsimile, - a control field C 3 of the frame which takes, in HDLC, one of two values depending on whether the frames are intermediate or final, ie that their transmission is followed by waiting for a response from the facsimile machine; a main control field FCF1 4 identifying the type of the digital signal among all those used for the facsimile transmission. This field is expressed in one byte; a field FCF2 5 of secondary control, optional and intended to specify FCF1. The contents of fields FCF1 and FCF2 define the format and nature of the data of an information field presented below - a data field FIF 6 of facsimile information in which the data of the image to be transmitted is represented. an FCS 7 field of redundancy protocol symbols capable of enabling the detection of an error affecting the transmission of the primary information or of the address information of the line to which the FCS field 7 is linked and, possibly, the correction of transmission error, the row redundancy protocol symbols of this field being determined by taking into account only information symbols of one line of the symbol block, of a length of sixteen bits and - a second field F 8 identical to the first field F 1.

 The address field A 2 of the frame is used to identify a broadcast procedure. Thus, all the frames belonging to the same broadcast procedure have an identical value of the address field 2, thus making it possible to mix the frames of several broadcast procedures transmitted in an interlaced manner. The flow switch is then used to rule out uninteresting broadcast procedures, that is to say that are not intended for the receiving device and / or are affected by error that are not likely to to be corrected.

 FIG. 4 illustrates the transmission of two multiplexed broadcast procedures (also called "interleaved") 60. Address fields 61, 65 and 69 are positioned at the same value and enable each reception device to identify frames 62. , 66 and 70 from a first broadcast procedure, on the one hand. On the other hand, address fields 63, 67 and 71 are positioned at the same value, different from that of the address fields 61, 65 and 69, and allow each receiving device to identify frames 64, 68 and 72 from a second broadcast procedure.

For the sake of clarity, the remainder of this description is limited to the transmission of a single broadcast procedure at a time, that is to say without another procedure being intertwined. In this description, the eight bits of the address field A2 each have the logic state "1"
The succession of fields from field A 2 to field FCS 7 corresponds to the complete description of a frame.

 The succession of fields from the A 2 field to the FIF 6 data field corresponds to the complete description of a data frame.

 The succession of fields from the main control field FCF1 4 to the FIF data field 6 corresponds to the complete description of the facsimile data.

 The modification of the meaning of the control fields and data fields of the facsimile frame, shown in FIGS. 1 and 3, makes it possible to improve the use of redundancy and allows the transmission in simplex mode, the addressing and the transmission. implementing a dynamic error correction.

FIG. 5 shows a starting SPI field, illustrated in FIGS. 12, 13 and 14, SPI being the initials of the English words "Service
Provider Identification ", and allowing the receiver to determine its interest in the broadcast message The SPI frame 10 is followed by a secondary control field FCF2 Il whose meaning makes it possible to specify the format of the information field.

 It should be noted here that the control field C 3 always takes the final value given the simplex exchange of the data, their transmission not being followed by waiting for a response from the facsimile machine. .

 The information field, which follows, is itself divided into 2 sub-fields, the field LIF 12 ("Label Information Field" in English) and the field DIF 13 ("Document Information Field" in English). The LIF field 12 and the DIF field 13 are data fields containing information relating to the broadcast message.

 Only the format of the DIF field is modified by the content of the secondary control field FCF2 11. When the format chosen by the sender is unknown to the receiver, the latter decides to abandon the reception of the current procedure.

 In order to allow broadcast reception by all listeners, the secondary control field must be set to ERA ("Every Receiver Allowed") as shown in Figure 12.

In this case, the format of the LIF field is defined as follows: its length is fixed at 20 bytes that can enable the receiver to identify the source of the document and to inform the user by mentioning this information in the header of the images broadcast , printing or displaying.

 It is noted here that the arrows presented in FIGS. 1 and 2 each correspond to at least one frame. By way of example, the RCP signal corresponds to three frames.

 The PPS frame (FIG. 1) as known to those skilled in the art is illustrated in FIG. 6. The PPS frame is illustrated in FIG.

 In FIG. 6, following fields 1, 2 and 3, the FCF1 field 14, the FCF2 field 15, then a page number field 16 which contains information representing the number of the page being transmitted are observed. , a block number field 17 which contains information representative of the data block number transmitted for the page indicated in the field 16, a field of frame number and end of information 18, then the fields 7 and 8 presented next to Figure 3.

 FIG. 7 shows that the PPS frame, implemented in conjunction with the present invention, is identical to the PPS frame known to those skilled in the art, with the exception of a frame number and a frame number field. beginning of redundancy 19, which is intercalated between the fields 18 and 7, presented above.

 Field 19 indicates the beginning of the redundancy in the data block and allows the variations of amount of redundancy from one block to another.

 FIG. 8 shows, in its upper line, the structure of an ECM error correction block, known in the prior art. This block comprises: a synchronization field 35, an information field 36, an RTC field 37 comprising a particular bit sequence making it possible to separate the useful information 41 from the stuffing information 38 in the last frame of the last frame. block, - a stuffing information field 38 which contains meaningless information, which serves only for the total number of information of the fields 36, 37 and 38 to be equal to a predetermined number of symbols and - a RCP field 39 Return to Control for Partial Page, back to the partial page control, used to delimit the message blocks, which allows to verify the length and therefore the integrity of the information transmitted in the whole block. ECM Return to Control for Partial page.

 The second line of FIG. 8 details the fields 36, 37, 38 and 39. The first three consist of a number 'Z' of FCD fields 40 themselves detailed to the left of the fourth line of FIG. of these FCD 40 fields, comprises successively and in order, a field F 1, a field A 2, a field C 3, a field FCF 1 4, a field FCF 2 5, an information field 41, a field RTC 37 , a stuffing field 38, an FCS field 7 (see FIG. 3) and a field F 8.

 The last field FCD 42 has the same fields as the fields FCD 40, to which are added the field RTC 37 and the stuffing field 38, between the information field 41 and the field FCS 7.

 Finally, the RCP field 39 is detailed to the right of the fourth line of FIG. 8. It comprises successively the field F 1, the field A 2, the field C 3, the field FCF 1 4, the field FCS 7 and the field F. 8, all these fields having already been presented above.

 Figure 9 shows the structure of an error correction block. This block comprises the same fields as the block of the prior art shown in FIG. 8, to which is added, between the stuffing field 38 and the RCP field 39, a redundancy field 43. This redundancy field comprises (second line of FIG. 9) FCD 44 fields numbered from 'Y to' 255 ', each of these FCD 44 fields comprising (fourth line of FIG. 9) a field F 1, a field A 2, a field C 3, a field FCF1 4, an FCF2 field 5, a redundancy information field 45, an FCS field 7 (FIG. 3) and an F 8 field.

 The number 'Y' is always strictly greater than the number 'X' and is 'X + 1' if the block is filled. 'Z' and 'X' identify the last useful frame of a block, on the one hand, in the prior art and, on the other hand, in the embodiment described and shown.

 FIG. 10 shows block formats in error correction mode, according to the prior art necessary for the transmission of the same page. On the left of FIG. 10, is represented the format of the first representative blocks of this page, each of these blocks comprising on one line: an FCD field 400, a line number in the block, number 401 ranging from '0' at '255', the so-called primary information representative of the image of the page to be transmitted 402 and an FCS field 403.

 When the two hundred and fifty-six lines as presented above have been transmitted, RCP frames 406 and PPS-NULL 404 are transmitted.

The last block relating to this same page, on the right in FIG. 10, is of smaller size, comprising only a number 'Z' of lines having the structure detailed above. Finally the RCP and PPS frames
MPS 405 are transmitted.

 As illustrated in FIG. 11, the same blocks comprise, in error correction mode, only 'Y' lines whose structure is detailed above, then a number equal to two hundred and fifty-six minus 'Y' lines in which the primary information is replaced by redundancy information 408. At the end of the two hundred and fifty-six lines thus constituted, the RCP and PPS-NULL frames 409 are transmitted.

 It is noted that the blocks of address information symbols are similarly constituted by lines having address information symbols (FIG. 15) and complementary lines in which there are redundancy information symbols. .

 The organization of the information symbols contained in the set of fields 407 and 408 is represented in FIG. 35. This illustrates, in a detailed way, the organization of a block of data before transmission 660.

 This structure allows the implementation of a new mode of block error correction, inspired by the structure of the ECM blocks (Figure 10) for error correction without request for retransmission of frames.

 Similarly, the last block comprises 'X + 1' lines whose structure is detailed above with respect to FIG. 9, then a number equal to two hundred and fifty six minus 'Y' lines in which the information representative of the image of the page are replaced by redundancy information.

FIG. 12 shows a start frame in which a field F 1, a field A 2, a field C 3, a field
SPI ("Service Provider Identification") 10, an ERA field 20 ("Every Receiver
Allowed "), a LIF field 21 with a length of 20 bytes, a DIF field 22 with a length of 9 bytes, an FCS field 7 (FIG. 3) and a field F 8.

The field ERA 20, corresponds to a digital signal of type
SPI says "SPI-ERA" indicating that the broadcast message is accessible to all.

The LIF 21 field contains additional information whose organization is free. The DIF field 22 includes information concerning the broadcast image representative information, namely, successively: - the current year and the current week, in two bytes - the type of media (fax, software,) in one byte - the document number, information
FF default, in one byte - broadcast number, information
FF default, one byte - page number, information
FF default, in one byte - the number of remaining broadcast, information
FF default to one byte - the number of pages remaining, information
FF by default, in one byte and - an annex, information valid
Default FF, in one byte.

FIG. 13 shows another start frame in which a field F 1, a field A 2, a field C 3, a field
SPI 10, a UGI field 23 ("User Group Identifier" in English), a LIF field 24 with a length of 20 bytes, a DIF field 25 with a length of 9 bytes, an FCS field 7 (FIG. an F 8 field.

The UGI field 23 corresponds to a digital signal of type
SPI says "SPI-UGI" indicating that the broadcast message is accessible by analysis of the user group field UG ("User Group").

 The LIF field 24 includes UG user group identifiers, i.e., information symbol source identifiers, providers and services offered, one of the identifiers thus indicating the service provider, and the other the type of service offered.

The DIF field 25 includes information on the representative image information broadcast, that is, in order, information that successively represent: - the current year and the current week, in two bytes - the type of media fax, software , in one byte - the document number, information
FF default, in one byte - broadcast number, information
FF default, one byte - page number, information
FF default, in one byte - the number of remaining broadcast, information
FF default, in one byte - the number of pages remaining, information
FF by default, in one byte and - an annex, information valid
Default FF, in one byte.

In FIG. 14, another start frame is observed in which a field F 1, a field A 2, a field C 3, an SPI field 10, a field PAI 26 ("Personal Addressing Identifier") follow one another. , a LIF field 27 with a length of 20 bytes, a DIF field 28 with a length of 14 bytes, an FCS field 7 (FIG. 3) and a field F 8. The PAI field 26 corresponds to a digital signal of the type SPI says "SPI-PAI" indicating that the broadcast message is accessible by analysis of the personal address field
PA ("Personal Address").

The field LIF 27 includes additional information whose organization is free. The field DIF 28 comprises, on the one hand, information on the representative image information broadcast and, on the other hand, information relating to the processing of personal addresses, that is, in order, information that successively represents - current year and week, in two bytes - type of fax, software, one byte - document number, information
FF default, in one byte - broadcast number, information
FF default, one byte - page number, information
FF default, in one byte - the number of remaining broadcast, information
FF default, in one byte - the number of pages remaining, information
FF by default, in one byte - an annex 00 to describe a
SPI-PA extension in one byte - the length of TAL 01 frames for 64
bytes, 04 for 256 bytes
(see figure 15), in one byte - the number of the last useful TAL frame, in one byte - the number of the first TAL frame
of redundancy, in one byte - the number of addresses in the last
useful frame, in one byte and - an annex, information worth
Default FF, in one byte.

 FIG. 15 shows, in the first line, the structure of an address list, in which synchronization fields 46, address list 47, stuffing 48, redundancy 49 and RCP 50 (" Return to Control for Partial page ". Address list 47 contains data representative of identifiers, or address, which are each solely related to a data receiving terminal.

 The second line details: - the list of addresses which includes the fields TAL 51 numbered '0' to 'T', the last of which contains the stuffing information of the field 48, - the field of redundancy 49 which comprises the fields TAL 54 numbered from 'U' to '255' and - the RCP field 50 which has RCP subfields 52. The TAL fields 51 each correspond to a digital signal carrying the list of PA personal addresses of the reception devices authorized to process the message. broadcasts.

It is observed, again, in FIG. 15 that in BECM mode (initials of the English words used by those skilled in the art "Bloc Error
Correction Mode "), a portion of the TAL frames convey redundancy information in the same manner as the FCD frames of Figure 8.

 The left-hand part of the fifth line of FIG. 15 illustrates the succession of fields constituting a TAL field 51, except however the last one which is illustrated in the third line: a field F 1, a field A 2, a field C 3, an FCF1 field 4, an FCF2 field 5, an address field 53 containing only address representative information, an FCS field 7 (FIG. 7) and a field F 8.

 The third line of FIG. 15 illustrates the succession of fields constituting the last TAL field 51, numbered 'T': a field F 1, a field A 2, a field C 3, a field FCF1 4, a field FCF2 5, an address field 53 containing address representative information, a stuff field 55, an FCS field 7 (FIG. 3) and a field F 8.

 The fourth line of FIG. 15 illustrates the succession of fields constituting a TAL field 54: a field F 1, a field A 2, a field C 3, a field FCF 1 4, a field FCF 2 5, a field of redundancies 56. containing only information for correcting transmission errors of the addresses present in the TAL fields 51, an FCS field 7 (FIG. 3) and an F 8 field.

 The right part of the fifth line illustrates the successive fields that constitute a CPR subfield: a field F 1, a field A 2, a field C 3, a field FCFI 4, a field FCS 7 (FIG. 3) and a field F 8.

In order to allow the reception of the broadcast by a group of individually identified users, the secondary control field 26 of the SPI frame, start frame, illustrated in FIG. 14, must be set to the value PAI. In this case, the LIF field contains information that does not intervene in the definition of the address. The information format of the DIF field is supplemented with format information relating to the address list. The SPI frame is immediately followed by the address list, transmitted as a block in BECM format, the same format used for data blocks, consisting of TAL ("Terminal Address List") frames.
With reference to FIGS. 9 and 15, it is observed that the address information symbols are treated in a manner similar to the primary information symbols.

The control frame presented in the first line of FIG. 16 comprises a field F 1, a field A 2, a field C 3, a primary control field at the value MOC 57 ("Management Oriented Command"), a field secondary control at the value SNR 58 ("Set New Right" in English), a field UG 30, a date field DATE 31, an FCS field 7 (FIG. 3) and a field F 8. The field MOC 57 corresponds to a digital signal for managing the terminals by broadcast commands. The field SNR 58 corresponds to a digital signal of MOC type called "MOC
SNR "to add a terminal to a group of users UG This frame is illustrated in Figure 16.

 The control represented by the MOC field 57, transmitted in phase A, is a priori independent of the addressing method. A description of the various fields of this command is given in FIG. 16, to define the new membership of a receiver to a group of users and FIG. 17 to define the former membership of a receiver to a group of users by modification of the contents of the memory area RIGHT ~ UGI 492.

 The UGI field 30, shown in the second line of FIG. 16, contains, over twenty bytes, user group identification information, i.e. a provider identifier and a service identifier provided.

The date field DATE 31, shown in the third line of Figure 16, contains four bytes of information which represent: - the current year and the current week, in two bytes - the next document number, on one byte and - an appendix , information worth
FF default, one byte.

 The control frame presented in the first line of FIG. 17 comprises a field F 1, a field A 2, a field C 3, a field MOC 57, a secondary control field at the value ROR 59 ("Reset Old Right", in English), a UG field 32, a date field DATE 33, an FCS field 7 (FIG. 3) and a field F 8. The field ROR 59 is a field of the MOC type, called "MOC-ROR", making it possible to remove a terminal of a user group UG.

 The UGI field 32, presented in the second line of FIG. 17, contains, over twenty bytes, user group identification information, i.e., a source identifier, a provider identifier, and a service identifier. Free.

The date field DATE 33, shown in the third line of Figure 17, contains four bytes of information that represent: - the current year and the current week, in two bytes - the last document number
authorized, in one byte and - an annex, information
FF default, one byte.

In FIG. 18, the successive transmission phases implemented in the embodiment described and shown are observed, the right-hand column of this figure indicating the number of repetition of the frames which is operated during transmission. We note, first, that all transmissions, symbolized by arrows, are from the left, representing the transmitter, to the right, representing the receiver, since this is a broadcast. In a first phase, referenced F,
The transmitter and receiver shown below are waiting for transmission. In the next phase, referenced A, the transmitter transmits a so-called "preamble" signal, meaningless signal that allows the different receivers to synchronize on the transmitter. Still in phase A, an SPI frame (shown in Figure 5) is sent five times. In this respect, we note that the
SPI can take here the form SPI-ERA (Figure 12) or the form SPI-UGI (Figure 13).

In phase B, a DCS frame (presented in Figure 1, phase
B) is issued ten times. In phase C each FCD frame in the format illustrated in FIG. 9 is transmitted once and the RCP frame is sent several (here ten) times.

 During phase D, the PPS frame is sent ten times. Phases C and D follow one another until all image representative information is emitted. Finally, during phase E, the DCN frame is transmitted ten times, before the transmitter and the receiver go into transmission waiting state, in phase F.

 The embodiment described and shown thus makes it possible to switch from a known type of telecopy protocol, illustrated in FIG. 1, to a so-called "simplex" facsimile protocol, that is to say, all transmissions of which are carried out a transmitter to several receivers, with the following modifications: - deletion of all acknowledgments; introduction of the SPI frame which triggers the closure of a flow switch illustrated in FIG. 24, the function of which is to initiate a broadcasting procedure and triggering of the opening of the flow switch upon reception of a DCN frame.

It is observed, moreover, that the error correction system operates in blocks, thanks to a modification of the structure of the data block and the PPS frames. Indeed, in the state of the art a data block consists of 256 FCD-type frames at most, numbered from '0' to '255', the entire message to be transmitted can be divided into several blocks, each block being separated by a PPS type frame, and the end of block being previously identified by a RCP frame (Figure 10). In the embodiment described and shown, the last frames of the data block, from 'Y' to '255', contain redundancy frames (FIG. 11). Type frames
PPS contain an additional field to identify this redundancy, by the number of the first redundancy frame in the block.

In the state of the art, in the PPS frame, whose type is defined by the FCF1 field 14 and specified by the FCF2 field 15, the information field
FIF is composed of 3 subfields, identifying respectively the number of the page, field 16, in the complete procedure, the number of the block, field 17, within this page and the number of the last useful frame of information, field 18, in the current block (FIG. 6).

 In contrast, in the embodiment described and shown, the PPS frame comprises an additional field, referenced 19, containing the number of the first redundancy frame (FIG. 7).

 The complete transmission of a data block is illustrated in FIG. 8 according to the state of the art and in FIG. 9 in the embodiment described and shown.

 FIG. 19 shows a variant of FIG. 18, in which the SPI frame is of SPI-PAI form (FIG. 14).

In a first phase, referenced F, the transmitter and the receiver are waiting for transmission. In the next phase, referenced
A, the transmitter transmits a "preamble" signal. Still in phase A, one SPI-PAI frame is sent five times, then each TAL frame is sent once, and then one RCP frame is sent ten times.

In phase B, a DCS frame is sent ten times. In phase C each FCD frame is sent once and the RCP frame is sent ten times. During phase D, the PPS frame is sent ten times. Phases C and
D follow each other until all the representative image information is emitted. Finally, during phase E, the DCN frame is transmitted ten times, before the transmitter and the receiver go into transmission waiting state, in phase F.

FIG. 20 represents a last variant of FIG. 18 with a MOC signal corresponding to a digital signal making it possible to manage the terminals by broadcast commands. In a first phase, referenced F, the transmitter and the receiver are waiting for transmission. In the next phase, referenced A, the transmitter transmits a "preamble" signal
Still in phase A, one SPI-PAI frame is erned five times, then each TAL frame is sent once, then one RCP frame is sent ten times and finally the MOC frames are sent ten times. Finally, during phase E, the frame
DCN is transmitted ten times, before the transmitter and the receiver go into transmission waiting state, in phase F.

 The repetition numbers of the transmitted frames are indicative and are advantageously adjusted by the quality control means 155 of the transmission device, which performs, in particular, according to rules called "ratio selection", a selection of a ratio defined between a number of redundancy information symbols on the number of symbols corresponding to them, depending on the transmission conditions, during the transmission (see below).

 Transmission of the SPI frame, start frame, corresponds to the start of the so-called characterization phase of the communication method of the embodiment described and shown.

 When the secondary control field of the SPI frame is set to PAI, the phase A comprises the transmission of the SPI frame and, immediately to follow, the transmission of the address list in the form of a block consisting of TAL frames, the same as for data in phase C.

 Phase E includes the transmission of the DCN frame, closing frame, which identifies the end of a complete procedure.

All the frames transmitted during a procedure
PAI, without remote management operation, is illustrated in FIG. 19, whereas all the frames transmitted during a PAI procedure whose purpose is to modify the membership of a user group is illustrated in FIG. .

In this case, we go directly from phase A to phase E.

 Fig. 21 illustrates the image diffusion system of the embodiment of the present invention. This system can also implement fax machines or other devices provided that the means incorporated in these devices are adapted to be implemented with the present invention. This system consists of a transmitting device and several receiving devices.

The transmission device is composed of an image analyzer 101, such as the scanner marketed by CANON whose reference is IX-30F, which provides a signal representative of an image of a document 100, connected by a SCSI interface to a microcomputer 102, also known to those skilled in the art as Terminal Processing Equipment of
Data, or "DTE", connected to a network, via a "DCE" 103, or Data Circuit Terminating Equipment, capable of transmitting data by adapting the signals transmitted by a terminal equipment to the characteristics of the line. Furthermore, the sending "DTE" 102 is connected to a reception "DCE" 108 for receiving the data transmitted via the "DCE" 103.

The microcomputer 102 is, here, the microprocessor type of the brand "INTEL" and reference 1486SX33. After analyzing the image to be transmitted 100 and formatting it, by the microcomputer 102, according to the communication method of the embodiment described and shown,
The information is transmitted to a "DCE" 103 via a standardized interface V24 in unidirectional transmission mode.

 For the receiving device, the broadcast information is communicated through a receive DCE 108 to a receiving DTE data processing module 106 via a standardized interface V24 in unidirectional receive mode. The bitstream of information can then be processed by a personal computer 104, in order to restore the original image 107 by means of a known printing means 105.

Different combinations of receive and transmit DCE combinations are proposed hereinafter - direct wired connection between the 2 sending and receiving DTEs, via a well known Null-MODEM serial cable. of the skilled person; radio broadcasting with a carrier whose frequency is 433.9 MHz, for example by means of modules referenced RM10 and marketed by the company SOFRACIN, the diffusion being carried out according to the European standard
ETS 300-220 and - broadcast known as "DIDON", using a subcarrier transmitting television signals by a broadcaster such as
France "TDF": the transmitting ETCD being a MODEM connected to the broadcast center, via a telephone network, and the receiving DCE being a receiving device of the "DIDON" method known as of "DIDEM".

This list is not limiting and the system can advantageously be adapted for satellite transmission, for broadcasting digital data, DAB type (in English "Digital Audio
Broadcasting ") or of frequency modulation type, for example in subcarriers.

 Fig. 22 is a hardware description of the receiving DTE 106. A V24 connector 110 is the physical interface between a serial link controller 111 and the receiving DCE 108. The serial link controller 111 is connected, of on the one hand, to the serial link connectors 110 and 119, to a parallel link connector 118 and, on the other hand, to a processor bus 115, itself connected to the main electronic components. The serial link controller 111 warns a microprocessor 116 of the reception of data broadcasted through the interrupt controller 117. The microprocessor 116 can then access, by a processor bus 115, to the registers of the serial link controller 111 to process the data received by the different reception devices located in a RAM RAM 114 in the "EXECUTION" zone The connection to the printing means is, in a known manner, via the parallel connector 118 via the controller link 111.

 A ROM 113 retains the operating system of the microprocessor 116 and makes it possible to automatically load, in the execution area of the RAM 114, the program stored in an erasable and programmable memory 112. Said memory 112, of a type known as the flash name EPROM, retains the program illustrated in FIG. 24, which organizes the operation of the device as well as the registers RIGHT UGI 492 and RIGHT PAI 493 which respectively contain the list of user groups UG to which the receiver belongs and the address personal PA of the receiver.

 FIG. 23 diagrammatically represents the transmission DTE electronic circuit 102: the scanner 101 is connected, through a not shown SCSI connector, to the SCSI controller 120, which symbolizes the interface card scanner IX-30F, marketed by the company CANON under the reference Sl-30, and which provides a digital signal representative of the image to be transmitted, here the image of the page 100, which is temporarily stored in the zone " REGISTERS "of a RAM 123. An IDE controller makes it possible to connect a storage unit which retains, on the one hand, the program that organizes the operation, illustrated in FIG. 25, of the" DTE "102 as well as the identifiers of the user groups UG, and the personal address PA of all the receivers known to the sender, and, on the other hand, the operating system of a microprocessor 125; the microprocessor 125 controls the operation of the other components of the sending DTE 102 via a bus 124 - a ROM 122 retains the basic system of the microprocessor 125 - the random access memory 123 keeps on the one hand, in the "REGISTERS" area, the variables, and on the other hand, the operating system, the program and the constants dynamically loaded in the "EXECUTION" zone from the storage unit - a V24 connector 127 is the physical interface between a serial link controller 129 and the transmit DCE 103 and a V24 connector 128 is the physical interface between the serial link controller 129 and the receive DCE 108. The link controller series 129 is connected, on the one hand, to the serial link connectors 127 and 128, and, on the other hand, to the processor bus 124. The serial link controller 129, on the other hand, allows the microprocessor to transmit the binary train to broadcast and, on the other hand, warns the microprocessor 125 of the reception of the bit stream being broadcast, intended for quality control, via the interrupt controller 126. The microprocessor 125 can then access, via the processor bus 124, to the registers of the serial link controller 129 in order to process, on the one hand, the data to be transmitted and, on the other hand, the data received thanks to the different transmission devices located in RAM RAM 123, "EXECUTION" zone; the interrupt controller 126, of known type, organizes the interruptions of the microprocessor 125 with particular regard to exchanges with the various controllers; and in addition, the transmit TEET 102 is equipped with all keyboard and screen interface peripherals, well known to those skilled in the art and not described herein.

 Figure 24 depicts the data streams between the different means composing the receiving DTE 106.

The implementation of the functions of the embodiment described and shown is more easily achieved through the use of a real-time monitor for managing multitasking processing, coupled with the means illustrated in FIG. 24, residing in RAM memory 114, in the "EXECUTION" area As an example we call the real time monitor "Real Time
Craft ", and this one is provided by the company GSI TECSI.

All the means presented in FIG. 24 operate asynchronously and autonomously and can exchange information via temporary memory registers located in random access memory 114 in a zone referenced "REGISTERS", and organized in FIFO, "First In
The real-time monitor used makes it possible, among other things, to suspend the operation of a means when it is waiting to be able to read on a memory FIFO momentarily empty.

 By way of reminder and convention for the rest of the description: a memory of the FIFO type contains at least one current reading element if it has validated at least one element that is current in writing and is otherwise empty; read is the first element validated in writing, - when validating the read or write FIFO type memory, the pointer corresponding to the read or write address, respectively, moves from an address of the memory to the following and the FIFO-type random access memories used subsequently are dimensioned so that they are never full.

 FIG. 24 introduces the main memory registers required for the reception DTE 106 enabling the flow of data between the various elements of the device.

 The memory zones FIFO ~ MSG 505, FIFO ~ TRX 506, FIFO ~ DATA 507 and FIFO ~ CMD 508, located in RAM 114 in the "REGISTERS" zone, are of the FIFO type and manipulate elements making it possible to store the longest of the HDLC format frames manipulated by the embodiment described and shown, such as that shown in Figure 3, without the start identifier 1 and frame end 8. The maximum length is of the order of 300 bytes.

 The FIFO ~ BLOCK 503 memory area, located in RAM 114 in the "REGISTERS" area, is also of the FIFO type and manipulates two separate element fields - a data block 670 shown in FIG. 36 and more precisely described later. a position register for identifying which lines of block 670 have been correctly received. 256 bits representing the numbers of the 256 lines of block 670, all having the same number of information symbols, are set to '1' if the lines they represent have been correctly received and to '0' otherwise. The organization of the symbols in the block 670 is given by the reception order, this order corresponding to the order of the symbols in the rows of the block and, in each line, to the order of the columns of the block.

 REG ~ FLUX register 504, located in RAM memory 114 in the "REGISTERS" area, determines the position of the flow switch 138 - if the value of register REG ~ FLUX 504 is '1', the flow switch is in the closed position, and the data flow is open and - if the register value REG ~ FLUX 504 is '0', the flow switch is in the open position, and the data flow is closed.

The opening of the flow switch 138 is symbolized by a signal FLUX OFF and, the closing of the flow switch 138, by a signal
FLOW ON.

 REG ~ ACCESS register 502, located in RAM 114 in the "REGISTERS" area, is used to validate access rights to the broadcast data.

RIGHT ~ UGI and RIGHT ~ PAI registers, localized in Flash
EPROM in the "SAVE" area, are used to respectively store the list of user groups UG to which the receiver belongs and the personal address PA of the receiver.

 The registers presented above are, furthermore, presented with reference to the flow chart or architecture figures of the device described and shown.

In FIG. 24, the data are physically received from the transmission medium by a reception DCE 108, controlled by a frame synchronization and flow control means 139 via a standardized serial interface of the V24 type, symbolized by the flow of data
RX V24.

 The frame synchronization and flow control means 139 is illustrated by the flowchart of FIG. 31. The frame synchronization and flow control means 139 is capable of extracting the protocol symbols, the correctly transmitted frames (FIG. operation 271), while eliminating repetitions, operation 272, and controlling the operation of the flow switch 138, in accordance with the following rules - upon receipt of an SPI type frame, first protocol symbols, closing the flow switch 138 is controlled, operation 274, symbolized by the signal FLUX ~ ON and - the opening of the flow switch 138 is controlled, operation 282, symbolized by the signal FLUX OFF on receipt of a frame type DCN, second protocol symbols.

 When the flow switch 138 is in the closed position, the received frame is stored in the FIFO ~ BLOCK 503 memory area, operation 278, if it is a FCD type frame (indicating primary information symbols) or TAL (indicating address symbols), and otherwise in FIFOIRX memory area 506, operation 280.

 It is noted that this means makes it possible to implement a first level of protection against transmission errors on the reception side, by the use of frame repetition, and this in a manner that is transparent to the reception communication control means 137.

 The reception communication control means 137 is illustrated by the flow charts of FIGS. 26, 27 and 29. It is, in particular, suitable for: implementing predetermined reception mode selection rules taking into account the first protocol symbols; and extracting, among the symbols received by the reception means, a ratio selected by the broadcasting device.

 The operation of the receive communication control means 137 continues whenever FIFO TRX 506 contains at least one item to be processed. The reception communication control means 137 verifies the proper sequencing of the different steps of the data transmission method in order to extract the broadcast information stored in the memory zones FIFO MSG 505 or FIFO ~ BLOCK 503.

 In case of non-compliance with the data transmission method, the opening of the flow switch 138 is controlled, symbolized by the signal FLUX ~ OFF by the control means 137, during the operations 208, 229 and 249.

The document selection means 134 is illustrated by the flowcharts of FIGS. 32 and 33. It allows, in particular, to transmit to the decoding means 630 only the primary information symbols which are associated with an address present in the one of the memories 492 and 493. The operation of the document selection means 134 continues each time FIFO ~ MSG 505 contains at least one element to be processed. The document selection means 134 checks the access to the broadcast information stored in the MSG 505 FIFO or FIFO ~ BLOCK 503 memory areas and, consequently, stores, on the one hand, the commands received in the memory zone. FIFO ~ CMD 508 and, on the other hand, the control of the pages received in
FIFO ~ DATA 507 and, otherwise, opens the flow switch 138, operation 319, symbolized by the signal FLUX ~ OFF. The document selection means 134 activates a decoding means 630 via the signal DEC ~ RQ, a signal which symbolizes the call to the implementation of the decoding means 630 in order to restore the content of the corrupted TAL frames. during transmission among the set of TAL frames received and stored in the FIFO ~ BLOCK 503 memory area.

 It is observed here that the so-called "corrupted" frames, also called "error-affected" are either missing or comprise, on reception, at least one information symbol different from the symbol corresponding to the transmission. Each line or frame identified as corrupted is said to be "erased", all the symbols of this line are therefore estimated to be zero. These symbols are more commonly known as "erasure" by those skilled in the art of coding.

 The DEC ~ ANS signal symbolizes the end of the processing performed by the decoding means 630 and the return to operation of the document selection means 134.

 The operation of the received page control means 135 is illustrated by the flowchart of Fig. 30. The operation of the received page control means 135 continues whenever FIFO ~ DATA 507 contains at least one item to be processed. The means for controlling the received pages 135 activates the decoding means 630 via the signal DEC ~ RQ, a signal which symbolizes the call to the implementation of the decoding means 630 in order to restore the values of the FCD type frames. corrupted during transmission, among all the FCD type frames received and stored in the FIFO ~ BLOCK 503 memory area. The DEC ~ ANS signal symbolizes the end of the processing performed by the decoding means 630 and the return to operation. the means of checking the pages received 135.

 The operation of the access rights management means 133 continues as long as FIFO ~ CMD 508 contains at least one element to be processed. On receipt of a command of MOC-SNR type access rights management means 133 stores the new user group UG in the register RIGHT UGI. On receipt of a command of the MOC-ROR type, the access rights management means 133 erases the old user group UG from the RIGHT UGI register.

 It is also noted that the means presented in FIG. 24 allow the passage of a known type of telecopy protocol, as illustrated in FIG. 1, with signals transiting from the receiver to the transmitter, to an image diffusion protocol. , without such signals. This is achieved in particular by virtue of - deletion of all the acknowledgments; introduction of the SPI frame which triggers the closing of the flux switch 138, whose role is to initiate a broadcasting procedure and triggering the opening of the flux switch 138 when receiving a signal. DCN frame.

 Figure 25 introduces the main memory registers required by the transmitting DTE 102 allowing the flow of data between the different elements of the device.

The memory zone FIFO ~ FRAME 522, located in memory
RAM 123 in the "REGISTERS" area, is of the FIFO type and manipulates elements making it possible to store the longest of the HDLC format frames used by the embodiment described and represented, such as that represented in FIG. 3, without the start identifiers. 1 and end of frame 8, the maximum length being of the order of 300 bytes
The memory zone FiFO ~ PAGE 520, located in RAM 123

 A temporary data block 535, located in the RAM 123, which is in the format of a pre-transmission data block 660, is used by the transmit communication control means 152 to perform the block cut comprising lines having all the same number of symbols, as well as the calculation of redundancy, pages to be broadcast. In particular, the transmission communication control means 152 organizes the symbols intended to be transmitted in blocks 660 (FIG. 25), the symbols then being successively diffused according to their position in said block, in the order of the lines and, in each line, in the order of the columns.

 FIG. 25 illustrates, under the same conditions as FIG. 24, the relationships between the different elements composing the transmitting DTE 102.

 A quality control means 155 stores in a memory named TX ~ PARAM 523, information representative of the quality of the data medium (or transmission medium) from the broadcast data that it receives from the DCE receiver 108, via a standardized serial interface type V24, symbolized by the RTX data stream V24.

The operation of the transmission communication control means 152 is carried out after the initialization of the HEADER 524 and FIFO PAGE 520 memory areas which contain, for the first time, the control, address, format and control information, relating to the content of the SPI, TAL, DCS and MOC frames, for the second, information symbols, called primary, representative of the images to be broadcast, organized in FIFO type memory. The transmission communication control means 152 activates a coding means 615 via the signal INK, which signal symbolizes the call for the implementation of the coding means 615 after having initialized the position of the primary information symbols. , or that of the address symbols, as well as the redundancy ratio, the value of which is stored in the memory TX ~ PARAM 523, by the quality control means 523. The signal
ENCANS symbolizes the end of the processing performed by the coding means 615 and the return to operation of the transmission communication control means 152.

 The transmission communication control means 152 is adapted to implement the "simplex" asynchronous digital communication method. It is adapted to generate and transmit the frames of the different phases of a broadcasting procedure of the embodiment described and shown. This means uses frame analysis means of known types of fax machines. This transmission means of communication admits variations in the number of repetition of the frames, without any consequences on its treatments. It therefore allows a dynamic variation of the repetitions according to the transmission conditions in cooperation with the dynamic management of the error correction.

This transmission communication control means 152 transmits frames, via a FIFO FIFO-type FIFO FIFO intermediate memory, to a means for transmitting the frames with repetition 151. This retransmits to a DCE D 103 transmission, via a TX ~ V24 interface, the same frame several times consecutively according to a number of repetition stored in the memory
TX ~ PARAM 523, by quality control means 523, which can be adjusted according to the transmission conditions. It integrates means for entramming data in HDLC format. It allows the implementation of a first level of protection against transmission errors: the frame repetition and this in a manner transparent to the transmission communication control means 152. It is recalled here that the HDLC entramage is a function existing in fax machines of known types.

 The means for transmitting frames with repetition 151 transmits all these data to the transmitting DCE 103, via a standardized V24 type interface between a DCE and a DTE, symbolized by the TX data stream. V24. In the particular case of the broadcast, it is only the transmission, byte by byte, of the broadcast data. Each byte ready for transmission is signaled by the repetition frame transmission function block.

 FIG. 26 illustrates the operation of the reception communication control means 137. FIG. 26 successively comprises, after the initialization phase 200, the sequence of operations described hereinafter.

 The test 202 causes a stop operation of the communication control means in reception 137 as FIFO ~ TRX 506 is empty.

On resuming the operation of the reception communication control means 137, the result of the test is positive if the current frame read in FIFOIRX 506 is SPI type. If the test is positive, the operation 201 is executed, otherwise the operation 208 is executed. The operation 202 thus makes it possible to extract, among the received symbols, first protocol symbols making it possible to select a reception mode, in the course of the operations presented, in particular, with reference to FIG.

 The operation 201 consists in copying the current frame in reading of FIFO ~ TRX 506 in the current write frame of FIFO ~ MSG 505 before validating the reading of FIFOIRX 506. Then the operation 203 is executed, the phase reception processing A, detailed figure 29.

 Next, the test 204 causes a stop of the operation of the communication control means in reception 137 as long as FIFO ~ TRX 506 is empty. When resuming the operation of the reception communication control means 137, the result of the test is positive if the current frame read in FIFO ~ TRX 506 is DCS type.

If the result of the test 204 is positive, the operation 205 is executed, otherwise the operation 207 is executed. During operation 205, the current read frame of FIFO ~ TRX 506 is saved in RAM 114 so that it can be used later by printing means well known to those skilled in the art and not described here. We then validate the reading of
FIFO TRX 506. Next, the ECM page receiving processing operation 206 is performed. Figure 27 details this operation 206.

 The test 207 determines whether a DCN signal has been received, or not. It is performed either after the operation 204 or after the operation 206 and causes a stop operation of the communication control means in reception 137 as FIFO ~ TRX 506 is empty, when its result is negative, by closing during the operation 208. When the operation of the reception communication control means 137 resumes, the result of the test 207 is positive if the current frame read in FIFO ~ TRX 506 is of the DCN type.

 If the test is positive, operation 209 is executed, otherwise operation 208 is executed. The operation 208 consists in positioning the contents of the register REG ~ FLUX 504 to the value '0', which amounts to opening the flow switch 138, then the reading of FIFO ~ TRX 506 is validated. Operation 209 consists in validating the reading of FIFO ~ TRX 506. After one of the operations 208 and 209, the test 202 is reproduced.

 The description of the frame synchronization and flow control means 139 is illustrated by the flowchart of FIG.

After the initialization phase 283, the frame synchronization and flow control means 139 is waiting for synchronization of a frame in HDLC format, such as that illustrated in FIG. 3, without transmission error, waiting identified by the first operation, referenced 271. The symbols representative of the received frame are stored in the current frame written in FIFO TRX 506.

Then, the test 272 is positive if the current frame written in
FIFO ~ TRX 506 is exactly the same as the frame previously written in FIFO ~ TRX 506, in order to filter the transmitted frames with repetition. The test 272 thus performs a comparison of successive sequences of symbols received and elimination of each sequence which is exactly identical to that which precedes it. If the test is positive, test 273 is executed, otherwise operation 271 is executed again. The test 273 is positive if the current write frame in FIFO TRX 506 is of type SPI. If the result of the test 273 is positive, the operation 274 is executed before the operation 275, otherwise the operation 275 is executed.

Operation 274 is to position the contents of the register
REG ~ FLUX 504 to the value 111, which amounts to closing the flow switch 138.

The test 275 determines whether the value of the contents of the register REG ~ FLUX 504 is equal to 'O', or not. If the test is positive, the test 281 is executed, otherwise the test 276 is executed.

 The test 276 is positive if the current write frame in FIFO ~ TRX 506 is either of the FCD type or of the TAL type. If the result of the test 276 is positive, the operation 278 is executed, otherwise the test 277 is executed.

The test 277 is positive if the current frame written in
FIFO TRX 506 is of the RCP type. If the result of the 277 test is positive,
Operation 279 is executed before operation 280, otherwise step 280 is executed directly.

 The operation 279 consists in validating in FIFO writing ~ BLOCK 503 indicating the completed reception of a block of data 670 illustrated in FIG.

 The operation 280 consists in validating in FIFOJRX writing 506 indicating the completed reception of a frame such as that illustrated in FIG.

 In the course of the operation 278, the symbols representing the FIFO field of the current write frame in FIFO ~ TRX 506 are stored in the data block 670 written in FIFO BLOCK 503, to the line indicated by the field FCF2. 5 of the current write frame in FIFO TRX 506. This line is stored as correctly received in the current position register in FIFO ~ BLOCK 503 (setting '1' of the bit representative of the position of the received line).

 The test 281, which succeeds the operations 278 or 280, or a positive result of the test 275, is itself positive if the current frame written in FIFO TRX 506 is of the DCN type. If the test is positive, the operation 282 is executed before returning to the operation 271, otherwise this feedback is directly performed.

Operation 282 consists in positioning the contents of the register
REG ~ FLUX 504 at the value '0' which corresponds to the opening of the flow switch 138.

 The A-phase receive process 203 of FIG. 26 is illustrated in FIG. 29 and is performed subsequent to the operation 201 of the receive communication control 137.

The test 241 determines whether the field FCF2 5 of the current write frame in FIFO ~ MSG 505 is of type ERA or not. If the result of the test 241 is positive, the operation 244 is executed. Otherwise the test 242 is executed. The test 242 determines whether the field FCF2 5 of the current frame written in FIFO ~ MSG 505 is of the UGI type or not. If the result of the test 242 is positive,
Operation 244 is executed. Otherwise, the test 243 is executed.

 The test 243 determines whether the field FCF2 5 of the current frame written in FIFO ~ MSG 505 is of type PAI, or not. If the result of the test 243 is positive, the test 245 is executed. Otherwise operation 249 is executed.

 We note here that the tests 241, 242 and 243 each allow the implementation of two modes of reception.

 The test 245 causes the communication communication control means 137 to stop operation as long as FIFOJRX 506 is empty.

On resuming the operation of the communication control means 137 in reception, the result of the test is positive if the current frame read in FIFO ~ TRX 506 is of type RCP. If the result of test 245 is positive,
Operation 246 is executed, otherwise operation 249 is executed.

 The operation 246 consists, on the one hand, in setting to the value '0' all the symbols of the lines of the data block 670 current in FIFO ~ BLOCK 503, including the representative bit, in the current position register in FIFO ~ BLOCK 503 is at 'O'. On the other hand, the positions of the lines, between that indicated by the contents of the eleventh octet and that indicated by the content of the twelfth octet of the LIF field 28 of the current write frame in FIFO ~ MSG 505, are stored as correctly received. in the current position register in FIFO ~ BLOCK 503 (setting '1' of the bit representative of the position of these lines).

 Then the test 247 determines whether the number of bits set to '0' in the current position register in FIFO ~ BLOCK 503 is strictly less than '256' minus the value of the content of the twelfth octet of the LIF field 28 of the current frame in writing in FIFO ~ MSG 505. If the result of the test 247 is positive, the operation 244 is executed, otherwise the operation 249 is executed.

 The operation 244 consists in validating in FIFO writing ~ MSG 505.

 During the operation 249, the content of the register REG ~ FLUX 504 is set to the value '0' which corresponds to the opening of the flow switch 138.

 The test 250 causes a stop operation of the communication control means in reception 137 as FIFO ~ TRX 506 is empty.

When resuming the operation of the reception communication control means 137, the result of the test is positive if the current frame read in FIFO ~ TRX 506 is of the MOC type.

If the result of the test 250 is positive, the operation 251 is executed, otherwise, the main operation of the reception communication control means 137 is returned, so that the current frame read in
FIFO ~ TRX 506 is analyzed by the test 204. During the operation 251, corresponding to the command reception processing, the current frame read in FIFO ~ TRX 506 is copied into the current frame in writing in FIFO ~ MSG 505, FIFO ~ TRX 506 is validated in reading and FIFO ~ MSG 505 is validated in writing.

 Then, the main operation of the receive communication control means 137 is returned to executing the test 204.

 The use of error correction involves particular processing performed by the ECM page reception process 206 within the receive communication control means 137. The ECM page reception process 206 of Fig. 26 is illustrated in Fig. 27 and is performed as a result of the operation 205 of the reception communication control means 137.

 The test 221 causes the operation of the communication communication control means 137 to stop as long as FIFO ~ TRX 506 is empty.

On resuming the operation of the communication control means 137 in reception, the result of the test is positive if the current frame read in FIFO ~ TRX 506 is of type RCP. If the result of the test 221 is positive,
Operation 231 is executed, otherwise operation 229 is executed. The operation 231 consists of validating in read FIFO ~ TRX 506.

 The test 222 causes a stop of the operation of the reception communication control means 137 as long as FIFOIRX 506 is empty.

When resuming the operation of the reception communication control means 137, the result of the test is positive if the current frame read in
FIFO TRX 506 is of the PPS type. If the result of the test 221 is positive, the operation 223 is executed, otherwise the operation 229 is executed.

The operation 223 consists, on the one hand, in setting to the value '0' all the symbols of the lines of the data block 670 current in
FIFO BLOCK 503, whose representative bit in the position current register in FIFO BLOCK 503 is at '0'.

 During the operation 224, the positions of the lines, between that indicated by the content of the field 18 and that indicated by the content of the field 19 of the current frame read in FIFO TRX 506, are stored as correctly received in the current position register in FIFO ~ BLOCK 503 (set to '1' of the bit representative of the position of these lines).

 Then the test 225 determines whether the number of bits set to '0' in the current position register in FIFO ~ BLOCK 503 is strictly less than '256' minus the value of the content of the field 19 of the current frame read in FIFO ~ TRX 506. The operation 225 thus makes it possible to check that any errors affecting the transmitted symbols are capable of being corrected. If the result of the test 225 is positive, the operation 226 is executed, otherwise the operation 229 is executed.

 The test 226 determines whether the field FCF2 5 of the current frame read in FIFO ~ TRX 506 is of NULL type or not. If the result of the test 226 is positive, the operation 230 is executed, otherwise the operation 227 is executed.

 During operation 227, the current read frame in FIFO ~ TRX 506 is copied to the current write frame in FIFO ~ MSG 505, and FIFO ~ MSG 505 is write enabled.

 The test 228 determines whether the field FCF2 5 of the current frame read in FIFO TRX 506 is of the MPS type or not. If the result of the test 228 is positive, the operation 230 is executed, otherwise the operation 232 is executed.

 Operation 230 consists of validating in read FIFO ~ TRX 506.

 Operation 233 consists in transmitting a reception fault signal. It corresponds to a request for transmission of information and makes it possible to inform the sending device of a reception defect, in particular if at least one error affecting a transmitted symbol is not capable of being corrected. In response to the operation 233, the receiving device may, according to variants of the embodiment described and shown, initiate a fax transmission procedure for the only receiving devices which perform the operation 233, according to the procedures detailed in the aforementioned T30 recommendation. In this variant, and preferably, the re-transmission of primary information symbols can be performed via a second transmission medium different from the transmission medium through which the broadcast procedures are performed, when the number of receiving devices having performed the operation 233 is low or through the same transmission medium, when the number of receiving devices having performed the operation 233 is high. Still according to this variant, the device and the reception method of the invention are adapted to receive symbols on two different transmission media, according to known techniques.

Operation 229 consists in positioning the contents of the register
REG ~ FLUX 504 to the value '0' symbolizing the opening of the flow switch.

 The operation 232 consists in validating in read FIFO ~ TRX 506.

Then return to the main operation of the receive communication control means 137 by executing the test 207.

 The description of the received page control means 135 is illustrated by the flowchart of FIG.

 After the initialization phase 267, the test 261 causes a stoppage of the control means of the received pages 135 as FIFO ~ DATA 507 is empty. On resuming operation of the received page control means 135, the result of the test is positive if the current frame read in FIFO DATA 507 is of the PPS type. If the result of the test 261 is positive, the test 262 is executed, otherwise the operation 266 is performed.

 The test 262 determines whether the value of the field N "BLOCK 17 of the current frame read in FIFO ~ DATA 507 is greater than or equal to 0. If the result of the test 262 is positive, the operation 263 is executed, otherwise operation 266 is performed.

In the course of the operation 263, are carried out: the initialization of the contents of the register DIM REG 558 equal to the number bit set to '0' in the current position register of FIFO ~ BLOCK 503. Let 'DIM' be the value contained in the register REG ~ DIM 558 and is RANGi the position of the ith bit to '1' in the current position register of FIFO ~ BLOCK 503. For 'i' varying from 'O' to 'DIM-1', the content the i th element of the painting
A (x) 555, Al, is 254-RANGI. If the value of the DIM-1 th element of the array A (x) 555 is negative then this element must take the value '255', - the initialization of the register R ~ LGTH 557 to '64', - the assignment of the address of the register BL ~ UNIT 562 to the address of the block of data 670 current in FIFO ~ BLOCK 505 and - the call to the implementation of the decoding means 630, symbolized by the triggering of the signal DEC ~ RQ.

 The operation 263 thus makes it possible to correct any errors affecting primary information symbols in the same way as address symbols, by implementing received redundancy information symbols, when the number of redundancy information symbols is enough to affect this correction.

 During the operation 264, the data block is saved in a print buffer and FIFO ~ BLOCK is read-enabled. During the operation 265, the value of the field N "BLOCK 17 of the current frame read in FIFO ~ MSG 505 is decremented, then the test 262 is reiterated.

 The operation 266 validates in reading FIFO ~ DATA 507, then the test 261 is reiterated.

 FIG. 32 illustrates the operation of the document selection means 134. This means makes it impossible to process a page or an order 298, if the processing authorization 297 has not been previously granted by the means of selection. analysis of the rights 293, ie if the content of the register REG ~ ACCESS 502 is at 'O'. The access right analysis performed during the operation 293 makes it possible to transmit to a correction step only the symbols that are associated with a stored address.

After the initialization phase 300, the test 292 causes a shutdown of the document selection means 134 as long as
FIFO ~ MSG 505 is empty. On resuming the operation of the document selection means 134, the result of the test is positive if the current frame read in FIFO ~ MSG 505 is of type SPI. If the result of the test 292 is positive, the test 294 is executed, otherwise the operation 298 is performed.

 During operation 298, the backup performed by operation 296 is destroyed. Operation 293 is then executed. The analysis of access rights 293 is detailed in Figure 33.

The test 294 determines whether the value of the contents of the current read register TYPE 510 is equal to the value of the contents of the register
TYPE ~ DATA 918 or not.

The test 294 causes a shutdown of the document selection means 134 as long as FIFO ~ MSG 505 is empty. When the operation of the document selection means 134 resumes, the result of the test is positive if the current frame read in FIFO ~ MSG 505 is of type
PPS. If the result of the test 294 is positive, the operation 296 is performed, otherwise the test 295 is executed.

 The result of the test 295 is positive if the current frame read in FIFO MSG 505 is of the MOC type and the operation 296 is performed, otherwise the test 292 is reiterated.

 The operation 296 consists in saving the current frame read in FIFO ~ MSG 505 in an area of the RAM memory 114 before activating in read FIFO ~ MSG 505.

Then test 297 determines if the value of the contents of the register
REG ~ ACCESS 502 is equal to '1' or not. If the result of test 297 is positive,
Operation 299 is executed, otherwise test 294 is reiterated.

Operation 299, on the other hand, stores in FIFO ~ DATA 507
The set of frames saved in PPS-type 296 by FIFO -changing data validation 507 for each of the frames, on the other hand, stores in
FIFO ~ CMD 508 The set of the frames saved in 296 of the MOC type by validating in FIFO writing ~ CMD 508 for each of the frames. Then, the test 294 is reiterated.

 The analysis of the access rights 293 of FIG. 32 is illustrated in FIG. 33. The execution of its first operation 311 is therefore done following the operation 298.

Operation 311 sets the contents of the register to '0'
REG ~ ACCESS 502.

 Then the test 350 determines whether the field FCF2 5 of the current frame read in FIFO MSG 505 is of type ERA or not. If the result of the test 350 is positive, the operation 320 is executed, otherwise the test 312 is executed.

 Then the test 312 determines whether the field FCF2 5 of the current frame read in FIFO MSG 505 is UGI type or not. If the result of the test 312 is positive, the operation 313 is executed, otherwise the test 314 is executed.

 During the operation 313, the content of the register REG ~ ACCESS 502 is set to the value '1' if the sequence of symbols forming the field LIF 24 of the current frame read in FIFO ~ MSG 505 is contained in the register RIGHT ~ UGI 492. This operation 313 thus performs a user group analysis and makes it possible to compare each received address and at least one stored address.

 Then the test 314 determines whether the field FCF2 5 of the current frame read in FIFO ~ MSG 505 is of type PAI or not. If the result of the test 314 is positive, the operation 315 is executed, otherwise the operation 319 is executed.

In the course of the operation 315, the initialization of the content of the register REG ~ DIM 558 equal to the number bit set to '0' in the current position register of FIFO ~ BLOCK 503 is carried out.
DIM the value contained in the register REG ~ DIM 558 and is RANGi the position of the i th bit to '1' in the current position register of FIFO ~ BLOCK 503. For 'i' varying from '0' to 'DIM-1 ', the content of the i th element of table A (x) 555, Ai, is equal to 254- RANG ?. If the value of the DIM-1th element of array A (x) 555 is negative then this element must take the value '255', - the initialization of the register R ~ LGTH 557 with the value contained in the tenth octet of the field DIF of the current frame read in FIFO ~ MSG 505, - the assignment of the address of the register BL ~ UNIT 562 to the address of the block of data 670 current in FIFO BLOCK 505 and - the call to the implementation of the decoding means 630, symbolized by the triggering of the signal DEC ~ RQ.

 The operation 315 thus makes it possible to correct any errors affecting address symbols in the same way as that of the primary information symbols, by implementing received redundancy information symbols, when the number of redundancy information symbols is sufficient to affect this correction.

Then, during the operation 317, the content of the register REG ~ ACCESS 502 is set to the value '1' if the sequence of elements contained in the register RIGHT ~ PAI 493 is also contained in the information lines of the data block 670 current in FIFO ~ BLOCK 505. Then
FIFO BLOCK 505 is validated for reading. This operation 317 thus performs a personal address analysis and makes it possible to compare each received address and at least one stored address.

 At the end of the operation 317 or that of the operation 313, the test 318 determines whether the content of the register REG ~ ACCESS 502 has the value '1' or not. If the result of the test 318 is positive, the operation 320 is executed otherwise the operation 319 is executed.

 The operation 319 consists in setting the content of the register REG ~ FLUX 504 to the value '0', which corresponds to the opening of the flow switch.

 The test 812 determines whether the FCF2 field of the SPI frame described in the 811 operation is of type PAI, or not. If the result of the test 812 is positive, the operation 813 is executed, otherwise the test 814 is executed.

In the course of the operation 813 are carried out: - for i varying from the number of the first primary information line LGEO 652 to the number of the last primary information line LGEj 659 of the data block 660 in HEADER, the following operations:
the current frame written in FIFO ~ FRAME 522 is initialized
to the TAL type, then the FCF2 field 5 and the IFF field 6 are
respectively assigned the value of the line number
primary information and the content of the third information line
primary data block 660 in HEAD 524 and
.FIFO FRAME 522 is then enabled in writing, - the initialization of the REG REG DIM 558 to the value of the contents of the redundancy field in TX ~ PARAM 523; Initialization of the 'DIM' elements of the array A (x) 555: Thus for 'i' varying from '0' to 'DIM-1', the content of the eleventh element of the array A (x) 555, Ai, is set to the value '256-DIM- ?,' DIM 'being the value of the contents of the register
REG ~ DIM 558; - The initialization of the register R ~ LGTH 557 with the contents of the field length frame in TX ~ PARAM 523; Assigning the address of the BL-UNIT register 562 to the address of the data block 660 in IN-HEAD 524; The call for the implementation of the coding means 615, symbolized by the triggering of the signal ENC ~ RQ; for i varying from the number of the first redundancy information line
LGEk 662 up to the number of the last redundancy information line
LGEn-1 664 of data block 660 in HEADER, the following operations
the current frame written in FIFO ~ FRAME 522 is initialized
to the TAL type, then the FCF2 field 5 and the IFF field 6 are
respectively assigned the value of the line number
primary information and content of the ith information line
primary data block 660 in HEAD 524 and
FIFO FRAME 522 is then validated in writing and - the current frame written in FIFO ~ FRAME 522 is initialized to the type
RCP and FIFO ~ FRAME 522 is validated in writing.

 The so-called "addressing" operation 813 provides reception device address symbols capable of enabling each receiving device to determine whether or not the primary information symbols transmitted during the operation 818 are intended for it. no, the identifiers, or address symbols are thus incorporated into information symbol sequences intended to be broadcast. Note that the address symbols are broadcast in blocks with line numbers, in the same manner as the primary information symbols.

 The test 814 determines whether the format field in HEAD-HEAD 524 indicates the transmission of a MOC-type frame, or not. If the result of the test 814 is positive, the operation 815 is executed, otherwise the operation 816 is executed.

 During operation 815, the current write frame in FIFO ~ FRAME 522 is initialized to the MOC type and the contents of the field FCF2 5 and the FIF field 6 are assigned the contents of the format field of HEAD-HEAD 524, then FIFO ~ FRAME 522 is validated in writing.

During the operation 816: the current frame written in FIFO ~ FRAME 522 is initialized to the type
DCS and the contents of the FIF field 6 is assigned the contents of the format field of
HEAD 524, before validating FIFO ~ FRAME 522 in writing, - the current frame written in FIFO FRAME 522 is initialized to the type
PPS-NULL and the content of the fields 16 and 17 is initialized to 'O', the content of the field 19 is assigned to the value '256' to which is subtracted the value of the redundancy field of the memory zone TX ~ PARAM 523 and finally the content of the field 18 is initialized to the value of the field 19 to which is subtracted '1', - the position of the current reading symbol, in the current page read in FIFO PAGE 520, is initialized at the beginning of said page and all the symbols of the temporary data block 535 are initialized 'O'.

Then, during the operation 817, iteratively, the symbol is copied, read current in the current page read in
FIFO ~ PAGE 520, before incrementing its position, in the temporary data block 535 which is in the format of a pre-transmission data block 660 in order to fill it line by line, from top to bottom and from left to right. the right - either to the line whose rank is indicated by the value of the field 18 of the current frame written in FIFO ~ FRAME 522 or - or to the last symbol of the current page in FIFO ~ PAGE 520 and in this case, the field 18 of the current write frame in FIFO FRAME 522 is updated with the number of the line being filled in the temporary data block 535.

Then, during the operation 818, the following is carried out: for i varying from the number of the first primary information line LGEO 652 to the number of the last primary information line LGEJ 659 of the temporary data block 535, the following operations:
the current write frame in FIFO FRAME 522 is initialized
to the FCD type, then the FCF2 field 5 and the IFF field 6 are
respectively assigned the value of the line number
primary information and content of the ith information line
primary of the temporary data block 535 and
FIFOJRAME 522 is then validated in writing; - the initialization of the REG register DIM 558 to the value of the contents of the redundancy field in TX ~ PARAM 523; The initialization of the DIM elements of the array A (x) 555: Thus for i varying from '0' to 'DIM-1', the content of the eleventh element of the array A (x) 555, Ai, is set to the value '256-DIM-', 'DIM' being the value of the contents of register REG ~ DIM 558; - Initialization of the register R ~ LGTH 557 to '64'; The assignment of the address of the register BL ~ UNIT 562 to the address of the temporary data block 535 - the call to the implementation of the coding means 615, symbolized by the triggering of the signal ENC ~ RQ, - for i varying the number of the first line of redundancy information
LGEk 662 up to the number of the last redundancy information line
LGEn-1 temporary data block 535, the following operations
the current frame written in FIFO ~ FRAME 522 is initialized
to the FCD type, then the FCF2 field 5 and the IFF field 6 are
respectively assigned the value of the line number
primary information and content of the ith information line
primary of the temporary data block 535 and
FIFO ~ FRAME 522 is then validated in writing and - the current frame written in FIFO FRAME 522 is initialized to the type
RCP and FIFO FRAME 522 is validated in writing.

Operation 818 thus makes it possible to determine redundancy information symbols capable of enabling error correction affecting information symbols and
The operations 813 and 818 jointly make it possible to broadcast all the information symbols to be transmitted, information symbols comprising the primary information symbols, the address symbols and the corresponding redundancy information symbols.

 The operations 813, 816, 817 and 818 jointly make it possible to organize the information symbols intended to be transmitted in blocks comprising lines all having the same number of symbols, the symbols of a block being successively diffused according to their position. in said block, in the order of the rows and, in each row, in the order of the columns.

 It will be noted that the primary information symbols and the address information symbols are respectively broadcast in advance of the corresponding redundancy information symbols. In addition, as described infra, the redundancy information symbols are determined by taking into account only the information symbols of a column of the block in question.

 The test 819, which follows the operation 818, determines whether the last symbol of the current page in FIFO ~ PAGE 520 has been copied into the temporary data block 535. If the test 819 is positive, the step 820 is executed otherwise step 821 is executed.

 During operation 820 the next frame written to FIFO ~ FRAME 522 is initialized with the content of the current frame written to FIFO ~ FRAME 522, before validating in FIFO writing ~ FRAME 522, - the contents of the field 17 of the current write frame in FIFO ~ FRAME 522 is incremented, - the content of field 19 of the current frame written to FIFOIRAME 522 is assigned to the value '256' to which the value of the field redundancy of the zone is subtracted TX memory ~ PARAM 523 and, the contents of the field 18 is initialized to the value of the field 19 to which we subtract '1' and - all the symbols of the temporary data block 535 are initialized '0'.

 The test 821 is negative if FIFO ~ PAGE 520 is empty and then the operation 823 is executed. Otherwise operation 822 is executed.

During operation 822: the next frame written to FIFO ~ FRAME 522 is initialized with the contents of the current frame written in FIFO ~ FRAME 522, and the field
FCF2 5 of the current write frame in FIFO ~ FRAME 522 is assigned to the MPS type, before validating in FIFO writing ~ FRAME 522, - the content of the field 16 of the current frame written in FIFO ~ FRAME 522 is incremented, - the content of field 17 of the current write frame in FIFO ~ FRAME 522 is set to '0', - the content of field 19 of the current frame written to FIFO ~ FRAME 522 is assigned to the value '256' to which the value of the redundancy field of the memory zone TX ~ PARAM 523 is subtracted and the content of the field 18 is initialized to the value of the field 19 to which is subtracted '1', - FIFO ~ PAGE 520 is validated in read before initialize the position of the current reading symbol, in the current page read in FIFO ~ PAGE 520, at the beginning of said page and - all the symbols of the temporary data block 535 are initialized '0'.

 In the course of operation 823, the field FCF2 5 of the current frame written to FIFO ~ FRAME 522 is assigned to the type EOP, before confirming in FIFO write FRAME 522.

After the operations 815 or 823, during the operation 824, the current frame written in FIFO ~ FRAME 522 is initialized to the type
DCN and FIFO ~ FRAME 522 is validated in writing. Operation 824 thus makes it possible to broadcast second protocol symbols capable of enabling each reception device to interrupt reception. The operation of the transmission control means is then completed.

 The quality control means 155 is illustrated by the flowchart of FIG.

 After the initialization phase 284, the quality control means 155 is waiting for synchronization of a frame in HDLC format, such as that illustrated in FIG. 3, waiting identified by the first operation, referenced 285. Next, the test 286 is positive if the frame has been received without transmission error and operation 287 is executed otherwise operation 288 is executed.

 The operation 287 counts each correctly received frame for each frame type, incrementing a counter associated with each frame type, while the operation 288 counts the erroneous frames by incrementing an erroneous frame counter. Each of these two operations updates a value representative of the good reception rate for each type of frame from the value of the different frame counters and from the contents of the fields of the memory zone TX ~ PARAM 523.

 Finally, the operation 289 makes it possible: to increase the value of the redundancy field of the TX ~ PARAM memory zone 523, according to predetermined rules, when the value of the good reception rate of the TAL or FCD type frames decreases, to decrease the value of the redundancy field of the TX ~ PARAM memory zone 523, according to predetermined rules, when the value of the good reception rate of the TAL or FCD type frames increases, - to increase the retransmission field of the TX ~ PARAM memory zone 523, associated with a frame type, according to predetermined rules, when the value of the good reception rate associated with said frame type decreases and - to decrease the retransmission field of the memory zone TX ~ PARAM 523, associated with a type of frame, according to predetermined rules, when the value of the good reception rate associated with said frame type increases.

 The ratio selection rules implemented during the operation 289 include the rule that the number of redundancy information symbols is always greater than would have been necessary to correct the transmission errors of the previous broadcast. information symbols.

 According to a variant not shown, the operation 289 and the operations associated therewith are carried out by a reception device, this reception device comprising a transmission means adapted to transmit, to the transmission device, a representative signal the transmission quality during the operation 289.

 Operation 285 is then executed again.

 Figure 35 shows the organization of a data block 660 prior to transmission, containing L x n information symbols including L x k primary information symbols.

 The set of primary information symbols from UO, O 650 to UL-1, O 651 represents the first line of the LGEO data block 652. A line of any data block such as LGEO 652 consists of L symbols. of information.

 The set of primary information symbols from UO, O 650 to UO, k-1,653 represents the first column of the data block for primary information symbols UO 654.

The set of redundancy information symbols since
WO, O 655 to WO, nk-1,656 represents the first column of the data block for the redundancy information symbols WO 657.

 The juxtaposition of UO 654 and WO 657 forms the first full column of the CLEO 658 data block.

A line of any data block, such as CLEO 658 consists of n information symbols.

 Regarding the first column CLEO 658, WO 657 contains the redundancy information symbols corresponding to the primary information symbols UO 654. In general, with respect to the 1st column CLEi 692, Wi 690 contains the symbols redundancy information corresponding to the primary information symbols Ui691.

 Figure 36 shows the organization of a data block 670 after receipt containing L x n information symbols.

 The set of information symbols from CO, O 665 to CL-1, O 666 represents the first line of the LGRO 667 data block.

A line of any data block, such as LGRO 667, consists of
L information symbols.

 The set of information symbols from CO, O 665 to CO, n-1668 represents the first column of the CLRO or CO 669 data block. A column of any data block, such as CLRi, or Ci 673 , consists of n information symbols.

The set of information symbols from CNO, O 674 to CNL-1, O 675 represents the first line identified as corrupted during transmission. For data block 670, this is also the line
CLRj 671. Thus the information symbols CNO, O 674 and CNL-1, O 675 can also be written respectively, CO, j and CL-1, j, and in general for all the symbols of this line, CNi, O = Cil By convention, Ci, j is an estimated zero symbol after reception and Cri, 0 is the regenerated symbol after decoding.

 Like line CLR 671, line CLRI 672 is also described as corrupt in our example of data block 670.

 The set of information symbols from CO, O 665 to CO, No. 668 represents the first column of the data block 670 for the received and / or estimated CO 669 information symbols.

 The set of CNO, O 674 and CNO information symbols, 1 676 represents the first column of the data block 670 for the CNO generated information symbols.

CNO is therefore a subset of the first column CO 669 of the data block 670. And in general, CNi is a subset of the i-th column Ci 673 of the data block 670.

 A known type of error correction system requires the knowledge of the values k and n. The error correction system has just knowledge of the value n, the value n-k being assumed to be exactly equal to the number of lines erased per received data block which is also the number of symbols erased in a complete column of the data block. For the data block 670 illustrated in FIG. 36, n-k is equal to 2 if it is assumed that all erased lines 671 and 672 are shown.

 The coding means 615 is adapted to calculate the associated redundancy information symbols, on the one hand to the primary information symbols Ui, and on the other hand to the address symbols, given the position of the symbols of redundancy information in the pre-transmission data block 660, specified, according to the assumed number of lines likely to be corrupted during transmission.

 The decoding means 630 is adapted to calculate the value of the erased information symbols associated with the received / estimated information symbols given the position of the erasures, to obtain, finally, the information symbols received and generated.

 The advantage of the error correction system described and shown lies in the fact that the decoding means 630 has no prior knowledge of the number of redundancy symbols actually calculated by the coding means 615.

 For the use of the encoding means 615 and decoding 630, described above, an organization of the memory is proposed hereinafter.

The constant-content registers, located in ROM memory and illustrated in FIG. 37 are the following: REG ~ N 540 contains the length of the code 'n', used for the coding of the column redundancy, mentioned above. 'n' also defines the maximum number of lines of the data blocks before transmission, block referenced 660, and after reception, block referenced 670, - REG ~ M 541 contains the value 'M' maximum number of lines of redundancy information that data block 660 can be calculated. This is also the maximum number of erased information lines that can be reconstructed per data block 670, - TAB TOEXP 542 is an array of 'n' elements. The Xth element of this array is the decimal value of the exponent i of the logarithmic representation of the symbol ', whose decimal value of the associated binary representation, is equal to X. This table gives the decimal value of the exponent of the logarithmic representation of a Galois body symbol GF (28), knowing the decimal value of its binary representation, - TAB ~ TOBYT 543 is an array of 'n' elements. The Xth element of this array is the decimal value of the binary representation of the symbol or
This table allows to know the decimal value of the binary representation of a Galois Go body symbol (28), knowing the decimal value of the exponent of its logarithmic representation and - REG ~ ROMAX 544 memory register whose value of the content indicates the maximum number of information symbols per line of the pre-transmission data block 660 or after reception 670. The contents of REG ~ ROMAX registers 544 and REG ~ N 540 define the maximum size of the pre-transmission data blocks 660 and after reception 670.

These registers also include variable content registers, located in RAM memory and illustrated in FIG. 38, the basic element being the byte, which also allows the exact representation of a symbol: OMEGA 545 contains the decimal value of the exponent i of the logarithmic representation of the symbol o 'represented, - 546 memory register whose essential task is to memorize the value of a count whose value is 547 memory register whose essential task is to memorize the value of a count whose value is 'j', - k 548 memory register whose main task is to store the value of a count whose value is 'k', - REG ~ ZERO 549 is used to store the consecutive values of the elements of the second line of the Vandermonde matrix to be reversed. The storage format is the decimal value of the exponent i of the logarithmic representation of the represented symbol o ', - A (x) 555 is in fact an array of length' M ', the value of which is stored in REG ~ M 541 , whose first element is represented by A0, the i-th by
Ai and finally the last by AM-1. A (x) 555 is representative of the position of the erasures after receiving the data blocks 670 and is representative of the position of the redundancy prior to transmission of the data block 660. The storage format is the decimal value of the exponent i of the logarithmic representation of the symbol o 'represented, - P (x) 551 is a 2-dimensional array of size M x M, used to store, line by line, the value of the elements of the inverse of a matrix of
Vandermonde, - PO (x) 559 is the first line of the 2-dimensional array P (x) 551. It is therefore an array of length M, the value of which is stored in REG ~ M 541, the first element of which is represented by P0,0, the ith by P0, i and finally the last by P0, MI. The storage format is the decimal value of the exponent i of the logarithmic representation of the represented symbol o>', - Pi (x) 560 is the ith row of the 2-dimensional array P (x) 551. an array of length M, whose value is stored in REG ~ M 541, whose first element is represented by Pi, 0, the ith by Pi, i and finally the last by
Pi, M-1. The storage format is the decimal value of the exponent i of the logarithmic representation of the represented symbol o ', - PM-1 (x) 561 is the last row of the 2-dimensional array P (x) 551. Therefore, a table of length M, whose value is stored in REG ~ M 541, the first element of which is represented by PM-1.0, the ith by PM-1, i and finally the last by PM-1, M- 1. The storage format is the decimal value of the exponent i of the logarithmic representation of the symbol o>, represented, - REG ~ VAL 550 is used to store the value of the polynomial Pi (x) at the particular point Ai. The storage format is the decimal value of the exponent i of the logarithmic representation of the represented symbol o>', - Q (x) 552 is an array of length M, whose value is stored in REG ~ M 541, whose first element is represented by Q0, the ith by Qi and lastly by QM-1. Q (x) 552 is representative of the outcome of the syndromes evaluation. The storage format is the decimal value of the binary representation of the symbol # represented, - S (x) 553 is an array of length M, the value of which is stored in
REG ~ M 541, whose first element is represented by SOle i th by Si and finally the last by SM-1. The storage format is the decimal value of the binary representation of the symbol # represented, - E (x) 554 is an array of length n, the value of which is stored in
REG ~ N 540, whose first element is represented by E0, the ith by Ei and finally the last by EM-1. The storage format is the decimal value of the binary representation of the represented symbol, - R ~ LGTH 557 memory register identifying the length of the lines, expressed in number of symbols, of the data block both before transmission 660 and after reception 670 This register can be variable for the needs of a particular embodiment, - REG DIM 558 memory register identifying the value of the number of redundancy information lines generated for the data block before transmission 660 or the number of lines of information erased in the data block after reception 670. Thereafter 'DIM' represents the value contained in the register REG ~ DIM 558 and - BL ~ UNIT 562 is a memory zone representing in fact a 2-dimensional array whose number of elements per line is the value contained in REG ~ ROMAX register 544 and the number of lines is equal to 'n'. This memory register enables the storage of the data block before transmission 660 or of the data block after reception 670. The storage format is the decimal value of the binary representation of the symbol o 'represented.

 The coding means 615 executes the various steps of the flowchart of FIG. 41 after the following initialization phase has been carried out: initialization of the contents of the register REG-DIM 558 with the value of the number of redundancy information symbols by column of the data block 660, such that this value is imperatively less than or equal to 'M', - initialization of the 'DIM' elements of the array A (x) 555: Thus for i varying from '0' to 'DIM-1 ', the content of the i th element of array A (x) 555, Ai, is set to the value' n-DIM- ', - initialization of register R ~ LGTH 557 with the value of the number of information symbol per line of the pre-transmission data block 660 and - assignment of the BLUNIT register 562 to a memory area representing a pre-transmission data block 660.

 The decoding means 630 executes the various steps of the flowchart of FIG. 41 after the following initialization phase - initialization of the contents of the register REG ~ DIM 558 with the value of the number of information symbols erased per column is carried out. data block 670, such that this value is imperatively less than or equal to .M '; - initialization of the 'DIM' elements of the array A (x) 555 to the value 'n-2', then, for i varying from 'O' to 'DIM-1', subtracting the number of the ith line deleted in data block 670 to the content of the i-th element of Table A (x) 555; initialization of the register LGTH 557 with the value of the number of information symbols per line of the data block after reception 670 and assignment of the BLUNIT register 562 to a memory zone representing a block of data after reception 670.

 FIG. 41 illustrates the flowchart of the various steps performed by both the coding means 615 and the decoding means 630.

 For an encoding operation, it is necessary to calculate the value of the elements of the array S (x) 553, corresponding to the value of the redundancy information symbols Wi 690 calculated from the primary information symbols Ui 691 of the block 660 illustrated in FIG. 35, i successively taking the value of the number of all the columns of the data block 660.

 For a decoding operation, it is a question of calculating the value of the elements of the table S (x) 553, corresponding to the value of the information symbols of the deletions CNi corresponding to the primary information symbols Ci 673 of the data block 670 illus

 The evaluation of the ith line of the inverse carried out during the operation 619 is illustrated in FIG. 39. This corresponds to the filling of the table Pi (x) 560, the second line of the 2-dimensional array P (x) 551.

 Then, during operation 620, 'i' is incremented by one.

Then the test 618 is reiterated.

 During the operation 621, 'k' is initialized to the value '0'.

 Then, the test 622 determines if 'k' is strictly lower than the value of the contents of the register R ~ LGTH 557, or not. If the test result is positive, operation 623 is executed. Otherwise, either all of the redundancy information is generated in the pre-transmission data block 660 in the case of an encoding operation or all of the corrected information is generated in the data block after reception 670 in the case of a decoding operation.

 In the course of the operation 623, the table E (x) 554 consists of the set of registers of the symbols of the kth column of the data block 660, when it is the coding, or 670, when it is is decoding.

The table S (x) 553 consists of all the registers of the information symbols to be generated, in this same column, the content of which has been initialized to '0'. Consequently, the elements of S (x) are either the redundancy information symbols Wk 691 of the kth column of the pre-transmission data block 660, or the generated information symbols Cnk of the kth column of the block of data after reception 670. The value of the contents of the OMEGA register 545 is set to '1', corresponding to the value of the exponent of the logarithmic representation of the symbol Q1 = o.

 The evaluation of the syndromes performed in the course of the operation 624 is illustrated in FIG. 40. This corresponds to the filling of the table Q (x) 552.

 Then, during the operation 625, the contents of the register i 546 is initialized to the value '0'.

Then, test 626 determines if 'i' is strictly less than 'DIM'. If the test result is positive, operation 628 is executed. If not,
Operation 627 is executed.

 During operation 627, 'k' is incremented by one.

Then the test 622 is reiterated.

 During the operation 628, the value of the i th element of the array Q (x) 552 is replaced by the value of the exponent of its algorithmic representation thanks to the conversion table TABIOEXP 542.

The value of this i th element of the array Q (x) 552 is then added together with the value of the i th element of the array Pk (x) 560. According to the rule of addition and subtraction of the exponents of the logarithmic representations of two elements of the Galois field 614 shown in the appendix, the value of the result being replaced by the value of its corresponding binary representation by means of the conversion table TAB ~ TOBYT 543. This result is applied to a
OR exclusive, bit by bit, with the value of the kth element of the array S (x) 553. The final result is stored in this last register.

 Then, during operation 629, 'i' is incremented by one. Finally, the test 626 is reiterated.

 Figure 39 illustrates the different steps of the evaluation of the i-th line of the reverse, performed after the test 618 of Figure 41.

 It is a question of calculating the value of the elements of the ith line of the 2-dimensional array P (x) 551. This also corresponds to the filling of the array Pi (x) 560. Previously, registers REG ~ DIM 558 and A ( x) 555 must have been affected.

 In the course of the operation 571, the content of the first element of the array Pi (x) 560 and the register j 547 is initialized to the value 'O'.

 The test 572 then determines if 'j' is strictly less than 'DIM', or not. If the result of the test 572 is positive, the operation 573 is executed.

Otherwise operation 579 is executed.

 During operation 573: - the day +? the same element of the array Pi (x) 560 takes the value of the jth element of the array Pi (x) 560; the value of the register k 548 takes the value of the register j 547 the value of the register REG ~ ZERO 549 takes the value of the jth element of the array A (x) 555 if 'j' is strictly less than 'i' and otherwise , the value of the register REG ~ ZERO 549 takes the value of the j + lth elements of the array A (x) 555.

 The test 574 then determines whether 'k' is strictly less than '1', or not. If the result of the test 574 is positive, the operation 577 is executed.

Otherwise operation 575 is executed.

 In the course of the operation 575: the content of the k th element of the array Pi (x) 560 is replaced by the value of the exponent of its algorithmic representation thanks to the conversion table TAB TOEXP 542, the value of the k th element of the table Pi (x) 560 is then added with the value of the contents of the register REG ~ ZERO 549 according to the rule of addition and subtraction of the exponents of the logarithmic representations of two elements of the Galois field 614 set out in the appendix; the value of the result is replaced by the value of its corresponding binary representation, thanks to the conversion table TAB ~ TOBYT 543 and - one applies to this result an exclusive OR, bit by bit, with the value of the k-1 th element of the Array Pi (x) 560. The final result is stored in the k th element of register Pi (x) 560.

 During operation 576, which follows operation 575 'k' is decremented by one.

 During the operation 577, the contents of the first element of the array Pi (x) 560 are assigned the value of the contents of the register REG ~ ZERO 549.

 Then, during operation 578, 'i' is incremented by one. Then the test 572 is reiterated.

 In the course of the operation 579, the content of the register REG ~ VAL 550 is initialized to the value of the content of the DIM th element of the array Pi (x) 560 and 'j' is initialized to 'DIM'.

 Then the test 580 determines whether 'j' is strictly greater than '0', or not. If the result of the test 580 is positive, the operation 581 is executed.

Otherwise, operation 583 is executed.

 During the operation 581 - the content of the register REG ~ VAL 550 is replaced by the value of the exponent of its algorithmic representation thanks to the conversion table TABIOEXP 542; the value of the i th element of the array A (x) 555 is then added with the value of the contents of the register REG ~ VAL 550 according to the rule of addition and subtraction of the exponents of the logarithmic representations of two elements of the Galois field 614 annexed; - the value of the result is replaced by the value of its corresponding binary representation thanks to the conversion table TAB ~ TOBYT 543 - one applies to this result an exclusive OR, bit by bit, with the value of the j-1 th element of the array Pi (x) 560 and - the final result is stored in the register REG ~ VAL 550.

 Then, during operation 582, 'j' is decremented by one.

 During the operation 583, 'j' is initialized to the value of the contents of the register REG ~ DIM 558.

 Then, the test 584 determines whether 'j' is strictly less than '0', or not. If the result of the test 584 is positive, the evaluation of the i-th line of the inverse is completed and the next operation 620 of Fig. 41 is executed.

Otherwise operation 585 is executed. This consists in the fact that: - the content of the jth element of the array Pi (x) 560 is replaced by the value of the exponent of its algorithmic representation thanks to the conversion table
TAB ~ TOEXP 542; the value of the jth element of the array Pi (x) 560 is then subtracted from the value of the contents of the register REG ~ VAL 550 according to the rule of addition and subtraction of the exponents of the logarithmic representations of two elements of the Galois field 614 exposed in the appendix and - the final result is stored in the jth element of the table Pi (x) 560.

 Then, during operation 586, 'j' is decremented by one.

 Figure 40 illustrates the various steps of the evaluation of the syndromes performed following the operation 623 of Figure 41.

 During the operation 596, all the elements of the array Q (x) 552 are set to the value '0'.

 Then, during operation 597, 'j' is initialized to '0'.

 Then the test 598 determines if 'j' is strictly less than 'n', or not. If the test result is positive, operation 599 is executed. Otherwise operation 601 is executed.

 In the course of operation 599, an exclusive OR, bitwise, is applied to the content value of the first element of array Q (x) 552 with the value of the content of the jth element of array E (x) 554. The final result is stored in the first element of array Q (x) 552.

 Then, during operation 600, 'j' is incremented by one. Finally, the 598 test is repeated.

During operation 601, is initialized to '1'
Then, test 602 determines whether 'i' is strictly less than 'DIM', or not. If the test result is positive, test 603 is executed. If not,
The evaluation of the syndromes is completed and the next operation 625 of Fig. 41 is executed.

 The test 603 determines whether 'j' is strictly less than 'n', or not. If the test result is positive, operation 605 is executed. Otherwise, operation 604 is executed.

In the course of the operation 604, the value of the OMEGA register 545 is summed with the value '1' according to the rule of addition and subtraction of the exponents of the logarithmic representations of two elements of the Galois field 614 set out in the appendix. The final result is stored in the registry
OMEGA 545.

 Then, during operation 606, 'i' is incremented by one. Then test 602 is reproduced.

 In the course of the operation 605, the content of the i th element of the array Q (x) 552 is replaced by the value of the exponent of its algorithmic representation thanks to the conversion table TAB TOEXP 542. The value of the i th element of the table Q (x) 552 is then added with the value of the contents of the register OMEGA 545 according to the rule of addition and subtraction of the exponents of the logarithmic representations of two elements of the Galois field 614 set out in the appendix. The value of the result is replaced by the value of its corresponding binary representation thanks to the conversion table TAB ~ TOBYT 543. This result is applied an exclusive OR, bit by bit, with the value of the jth element of the array E (x ) 554. The final result is stored in the k th element of array Q (x) 552.

 Then, during operation 607, 'j' is incremented by one. Finally, the test 603 is reiterated.

 It is noted that, for example by using frames intended for non-standard applications (so-called "NSF" frames, initials of the English words used by the person skilled in the "Non Standard Facilities" art), the transmission device and the reception device exchange specific signals allowing each of them to identify the other as likely to implement an error correction using redundancy information symbols to correct the transmitted primary information symbols.

Annex. calculation rules:
The rules for addition and subtraction of the exponents of the logarithmic representations of two elements of the Galois field 614 are: - either 'X' the multiplication associated with the Galois body Go (28), - or i the value of the exponent associated with the logarithmic representation of the symbol cu 'of the Galois body GF (28), - let j be the value of the exponent associated with the logarithmic representation of the symbol # of the Galois field C; F (28), - let k be the value of the exponent associated with the logarithmic representation of the symbol o> k = # x # of the Galois field GF (2x) and - let 1 be the value of the exponent associated with the logarithmic representation of the symbol # = # x 1 / #, of GF Galois body (28).

We then have the following 2 calculation rules - Rule 614 for the addition is:
if the value i is equal to '255' then the value k is in all cases equal to '255',
if the value j is equal to '255' then the value k is in all cases equal to '255',
and otherwise
if the sum of the value i and the value j is strictly less than 255 then the value k is equal to the sum of the value i and the value j,
If the sum of the value i and the value j is greater than or equal to 255 then the value k is equal to the sum of the value i and the value j to which we subtract '255', - Rule 614 for the subtraction is:
if the value i is equal to '255' then the value k is in all cases equal to '255',
if the value j is equal to '255' then the value k is in all cases invalid,
and otherwise
if the value i is greater than or equal to the value j then the value k is equal to the difference of the value i and of the valuej,
if the value i is strictly lower than the value j then the value k is equal to '255' to which is subtracted the difference of the value i and the value j,
Theoretical description of the system
The variable redundancy error correction method comprises the various steps to be implemented in the error correction system, coding / decoding means, operating indifferently to decoding, regardless of the redundancy or error correction threshold. defines for coding.

 In general, this variable redundancy error correction method is based on the localized erasure correction principle, applied to the columns of the data block, as shown in FIG.

The method of locating the erasure detection / location of erased / not received lines in the block is known to those skilled in the art and is therefore not described here.

 On transmission, M is the maximum number of erased lines that can be corrected in a block, for a given block. This number M defines the maximum value that can be taken by the number of redundancy lines (nk), determined on transmission for the coding means 615, according to the information coming from, for example a quality control means, not shown. in the figures.

 On reception, after having stored and completed the frames received in the same block, the decoding means 630 is used to redial the entire block regardless of the number of lines erased. The reconstruction of the block is done column by column.

 Knowing the position of the erased symbols in a column, the method and the device implemented by the embodiment described and shown, are capable of recomposing up to X symbols erased with X redundancy symbols. However, since the decoding means is not informed of the number (n-k) of current redundancy lines, it performs the correction regardless of the number of erased lines. It is therefore possible to make a correction wrongly if the number of erased lines is greater than (n-k). This eventuality must be controlled by any method appropriate to the application in question. It is obvious that a system can define a maximum erasure threshold beyond which no correction operation is triggered and the data block is then considered lost. This threshold may advantageously be fixed at M.

 Sequentially or in parallel, each of the columns of the block is processed in order to recompose each line in its entirety.

 The same functional modules can be advantageously used for both coding and decoding and only the value of the output input parameters differentiates an encoding operation from a decoding operation.

The implementation of a correction system described below and called in the remainder of the description "CID" is based, on the one hand, on the mathematical theory of Galois bodies, well known to those skilled in the art. , and more particularly here, on the GF body (28) and its associated addition and multiplication operations, the 256 elements of the body being able to be represented in their binary form or in their equivalent logarithmic form, and, on the other hand, on the manipulation of an nx M parity matrix of Vandermonde type, well known to those skilled in the art. The content of this parity matrix H, is explained below, with a logarithmic representation of its elements.

The length of the code, for the purposes of our realization, is therefore fixed at 256, so we have n = 256.

The parity matrix highlights the constant M, the value of which determines the limitations of the CID system. The value of this constant
M defines the maximum number of redundancy lines per block, the number (nk) of redundancy lines per block can thus vary from 0 to M.

Recall briefly the basic theoretical principles, well known to those skilled in the art:
Coding principle: - or U ,, the vector representing the k primary information symbols of column i of the data block, - or W ,, the vector representing the nk redundancy information symbols of column i of the block of data. Let nk <M, - be the vector representing the set of n information symbols in column i of the data block and - let Hk be the matrix constructed from the first k rows of matrix H
Let us write the matrix Hk as the juxtaposition of two matrices H, and H ,, where H1 represents the first k columns of Hk and H ,, and its last nk columns. The redundancy can then be represented as follows:
W1T = -H1'-1.H1.U1T where W, 'represents the transpose of the vector W, and U, represents the transpose of the vector U1.

 Decoding principle: either C ,, the vector representing all the n information symbols of the column i of the data block, the symbols not correctly received having been set to zero, their position having been located at the reception of the data block, - let R be the set of previously erraded IRI positions, - let H be the matrix constructed from the IRs (first rows of the matrix II, - let H2 be the sub-matrix of H containing the IR R columns). according to the position of the erased symbols marked in the set R and - or T, the vector representing all the R information symbols corresponding to the erased positions.

où 7;' représente la transposée du vecteur 25 et C', représente la transposée du vecteur C,. We can thus write:

where 7; represents the transpose of the vector 25 and C ', represents the transpose of the vector C ,.

The interest of this method rests on the flexibility of the algorithm of inversion of a Vandermonde type matrix of which one recalls here some great principles implemented here: - let P be a matrix of Vandermonde whose representation is:

Let's represent (P) -1 as follows:

 By definition of the inverse matrix, (P) -1. (P) = where IDIM is the identity matrix.

If one puts: P1 (x) = P1,0 + P @, 1x + P1,2x + ... + P1, DIM-1xDIM-1 + P1, DIM for i varying from O to DIM, we deduce the following expressions
P0 (A0) = 1, P1 (A0) = 0, PDIM (A0) = 0,
P0 (A1) = 0, P1 (A1) = 1, PDIM (A1) = 0,
P0 (ADIM) = 0, P1 (ADIM) = 0, PDIM (ADIM) = 1.

If we put A (x) = (x-A0) x (x-A1) x ... x (x-ADIM), then

 According to the principles mentioned above, the construction of (H @) - 1, which is a decisive decoding step, depends only on the knowledge of the positions of the erased frames. No additional prior knowledge is therefore necessary to perform the decoding operation.

For this reason the decoding operation is independent of the number of redundancy lines. It is of course obvious that the correction performed can only be validated if the number of erased lines is not greater than the number of redundancy lines in the block. This information does not belong to the decoder but to the means responsible for controlling the decoder.

 The evaluation of a line of the inverse matrix illustrated in FIG. 39 is based on a suitable implementation, for the purposes of the explanation, of the inversion principle of a Vandermonde matrix described above.

Claims (37)

 A device (101, 102, 103) for displaying primary information symbols representing a physical quantity, via a transmission medium, symbols that can be simultaneously received by a plurality of reception devices (104). , 105, 106, 108), diffusion device characterized in that - it takes into account:  an estimate of transmission quality on the medium of  transmission and  a ratio of a number of information symbols of  redundancy, likely to allow the correction of errors  assigning primary information symbols, on the number  of primary information symbols corresponding to the  redundancy information symbols, and - it comprises:  ratio selecting means (155) adapted to implement  implement rules called "ratio selection" predetermined  taking into account a transmission quality estimate  on said transmission medium, to select said ratio  among a plurality of ratio values,  means for determining (615) information symbols  of redundancy whose number corresponds to the ratio  selected, and  . means for transmitting (103, 151) information symbols  primary and redundancy information symbols.  The broadcast device according to claim 1, characterized in that the predetermined ratio selection rules (289) include the rule that the number of redundancy information symbols transmitted increases as the estimated transmission quality decreases.  3. Broadcast device according to claim 1, characterized in that the ratio selection rules comprise the rule that the number of redundancy information symbols is always greater than what would have been necessary for correct the transmission errors of the previous dissemination of information symbols.  4. Broadcasting device according to any one of claims 1 to 3 characterized in that it comprises: - a receiving means (108) identical to at least one receiving means of a said receiving device, said means of receiving the broadcast device being adapted to receive said scattered information symbols; and - estimating means (135, 155, 630) of the number of errors affecting primary information symbols received by the reception means of the communication device. broadcast adapted to provide a transmission quality estimate on said transmission medium, said ratio selecting means being adapted to take into account said quality estimate.  5. Broadcasting device according to any one of claims 1 to 4, characterized in that it comprises an insertion means (152) adapted to insert, among information symbols to be transmitted, protocol symbols. corresponding to lines of information symbols in said block.  6. information symbol diffusion device according to any one of claims 1 to 5, characterized in that it comprises a means of repetition (151) adapted to repeat sequences of symbols and in that it is adapted to increase the number of repetitions (289) performed by the repeating means when the transmission quality estimated by the quality estimating means decreases, the transmitting means being adapted to transmit each sequence of symbols repeated by said means of transmission; repetition.  7. Broadcasting device according to any one of claims 1 to 6, characterized in that it comprises an insertion means adapted to insert, among information symbols to be transmitted, control information symbols. representative of the redundancy ratio selected by the selection means.  8. Broadcasting device according to any one of claims 1 to 7, characterized in that it comprises: - receiving means (108) adapted to receive from at least one said receiving device, symbols received by said receiving device, and - estimating means (155) of the number of errors affecting primary information symbols received by said receiving means adapted to provide a transmission quality estimate on said transmission medium, said ratio selection means being adapted to take into account said quality estimate.  9. Broadcast device according to any one of claims 1 to 8, characterized in that it comprises a receiving means (108) adapted to receive from at least one said receiving device, information symbols. representative of a transmission quality estimate on said transmission medium, the ratio selecting means being adapted to take into account said quality estimate.  10. A primary information symbol broadcasting device according to any one of claims 1 to 9, symbols that can be received simultaneously by a plurality of reception devices adapted to implement at least two reception modes (241, 242, 243) of said symbols, said device comprising a redundancy information symbol determining means (615) capable of correcting errors affecting primary information symbols and being characterized in that the broadcasting means ( 103,151) is adapted to broadcast: - first protocol symbols (20) capable of allowing each receiving device to select a reception mode to be implemented; all the information symbols (407) to be transmitted, information symbols comprising primary information symbols and redundancy information symbols corresponding to these primary information symbols; and second protocol symbols capable of allowing each reception device to interrupt the reception.  11. A reception device (104, 105, 106, 108) of primary information symbols representing a physical quantity, transmitted via a transmission medium by a broadcasting device (101, 102, 103), and capable of being received simultaneously by a plurality of receiving devices, receiving device comprising symbol receiving means (108, 139) from the broadcasting device, and being characterized in that: - it takes into account a ratio a number of redundancy information symbols transmitted by the broadcasting device and capable of correcting errors affecting primary information symbols, with respect to the number of primary information symbols corresponding to these symbols of redundancy information, and - it comprises:  extraction means (137), among the symbols received by the  means of reception, of a ratio selected by the  diffusion, and  error correction means (630) affecting  primary information symbols adapted to implement a  number of lower redundancy information symbols or  equal to the number corresponding to the selected ratio, for  correct errors affecting information symbols  primary.  12. A primary information symbol receiving device (104, 105, 106) representing a physical quantity, transmitted via a transmission medium by a broadcast device (101, 102, 103), and received by via means for receiving symbols (108, 139) from the broadcasting device, reception device characterized in that: - it takes into account a ratio of a number of redundancy information symbols transmitted by the broadcasting device and capable of correcting errors affecting primary information symbols, with respect to the number of primary information symbols corresponding to these redundancy information symbols, and - it comprises:  extraction means (137), among the symbols received by the  means of reception, of a ratio selected by the  diffusion, and  error correction means (630) affecting  primary information symbols adapted to implement a  number of lower redundancy information symbols or  equal to the number corresponding to the selected ratio, for  correct errors affecting information symbols  primary.  13. Receiving device according to any one of claims 11 or 12, characterized in that it comprises - transmission quality estimation means (135, 630) adapted to provide an estimate of transmission quality on said support and transmission means adapted to transmit, to said broadcasting device, a signal representative of said transmission quality.  14. Reception device according to claim 13, characterized in that it comprises an error-affected information symbol detection means (135) adapted to detect each error-affected information symbol and in that said quality estimation takes into account according to predefined quality estimation rules, the detection of information affected by error of information symbols transmitted by a transmission device.  15. Receiving device according to any one of claims 11 to 14, characterized in that it comprises transmitting means adapted to transmit to the broadcast device, information symbols received by the receiving means ( 108, 139).  16. Receiving device according to any one of claims 11 to 15, characterized in that, the primary information symbol broadcasting device inserting, among transmitted protocol symbols, successive line numbers corresponding to lines of data. information symbols in a block, the receiving device comprises transmission quality estimation means (135) adapted to detect the absence of line numbers in the received information symbols.  17. receiving device according to any one of claims 11 to 16 characterized in that - it comprises an error detection and counting means (135) affecting at least one primary information symbol adapted to provide representative information a number of errors, and - the error correction means (630) is adapted not to correct (225, 233) the errors affecting the primary information symbols for which the ratio selected by the broadcasting device corresponds to a number of errors less than the number of errors represented by the information provided by the detection and counting means.  An information symbol receiving device according to any one of claims 11 to 17, information symbols comprising primary information symbols and redundancy information symbols corresponding to these primary information symbols and capable of to allow an error correction affecting said information symbols, this receiving device being characterized in that it comprises: - extraction means (139), among the symbols received from the broadcasting device, first and second protocol symbols, and - a means for selecting a reception mode (137) adapted to implement predetermined "receive mode selection" rules taking into account the first protocol symbols, for selecting a reception mode among reception modes each comprising, on the part of the reception device, no transmission of signals intended for the reception device broadcasting, until the broadcasting device has broadcast all the primary information symbols to be transmitted, the receiving means being adapted to implement the reception mode selected by the selection means; and a reception interruption means (138), adapted to cooperate with the reception means to interrupt the reception performed by the reception means when the extraction means has extracted the second protocol symbols.  19. Method for broadcasting primary information symbols representing a physical quantity, via a transmission medium, symbols that can be received simultaneously by a plurality of reception devices (104, 105, 106, 108) characterized in that: - it takes into account:  an estimate of transmission quality on the medium of  transmission and  a ratio of a number of information symbols of  redundancy, likely to allow the correction of errors  assigning primary information symbols, on the number  of primary information symbols corresponding to the  redundancy information symbols, and - it comprises:  a ratio selection step (286 to 289) during  which is implemented rules called "selection of  predetermined ratio taking into account an estimate of  transmission quality on said transmission medium, for  selecting said ratio from among a plurality of ratio values,  a step of determining (813, 818) symbols  of redundancy information during which one  determines redundancy information symbols whose  number is the selected ratio, and  a step of issuing (813, 818) information symbols  primary and redundancy information symbols.  The broadcast method according to claim 19, characterized in that the predetermined ratio selection rules comprise the rule that the number of redundancy information symbols transmitted increases when the estimated transmission quality decreases.  21. Broadcasting method according to any one of claims 19 or 20, characterized in that the ratio selection rules include the rule that the number of redundancy information symbols is always greater than what would have been necessary for correct the transmission errors of the previous dissemination of information symbols.  22. Broadcasting method according to any one of claims 19 to 21 characterized in that it comprises: - a receiving step (206) in which is made to receive the broadcast device the primary information symbols so identical to a said receiving device, - a step of estimating the number of errors (288), during which it is estimated that a number of errors affecting primary information symbols received during the reception step of the broadcast device, and a transmission quality estimate (289) is provided on said transmission medium, the selection made during the ratio selection step taking into account said quality estimate.  23. Broadcasting method according to any one of claims 19 to 22, characterized in that it comprises an insertion step during which is inserted, among information symbols to be transmitted, protocol symbols. successive line numbers corresponding to lines of information symbols in said block.  24. A method of broadcasting information symbols according to any one of claims 19 to 23, characterized in that it comprises a repetition step, during which repeats sequences of symbols and in that one makes grow the number of repetitions performed by the repeating means when the transmission quality estimated during the quality estimation step decreases, each sequence of repeated symbols being transmitted during the transmitting step.  25. Broadcasting method according to any one of claims 19 to 24, characterized in that it comprises an insertion step, during which is inserted, among information symbols to be transmitted, symbols d control information representative of the redundancy ratio selected during the selection step.  26. Broadcasting method according to any one of claims 19 to 25, characterized in that it comprises: - a receiving step (285 to 289) during which one receives, from at least one said device receiving, symbols received by said receiving device, and - a step of estimating number of errors (286-289), in which the number of errors affecting primary information symbols received at during the receiving step, and during which a transmission quality estimate (289) is provided on said transmission medium, said quality estimate being taken into account during the ratio selecting step.  27. Broadcasting method according to any one of claims 19 to 26, characterized in that it comprises a receiving step, during which is received, from at least one said receiving device, symbols of information representative of a transmission quality estimate on said transmission medium, and said quality estimate is taken into account during the ratio selection step.  28. A method of broadcasting primary information symbols according to any one of claims 19 to 27, symbols that can be received simultaneously by a plurality of reception devices adapted to implement at least two reception modes (241, 242, 243) of said symbols, this method being characterized in that it comprises, successively: a step of broadcasting first protocol symbols (811), during which first protocol symbols are diffused which can enable each reception device of selecting a reception mode to be implemented; The broadcasting step (818), during which all the information symbols intended to be transmitted are diffused, information symbols comprising, on the one hand, primary information symbols and, on the other hand, , redundancy information symbols corresponding to these primary information symbols; and a step of broadcasting second protocol symbols (824), during which second protocol symbols are diffused capable of allowing each reception device to interrupt the reception.  29. A method of receiving primary information symbols representing a physical quantity, transmitted via a transmission medium by a broadcasting device (101, 102, 103), and capable of being simultaneously received by a plurality of reception devices (104, 105, 106, 108), the method comprising a step of receiving (206) symbols from the broadcasting device, and being characterized in that - it takes into account a ratio of a number of redundancy information symbols issued by the broadcasting device and capable of correcting errors affecting primary information symbols, with respect to the number of primary information symbols corresponding to these redundancy information symbols, and - it comprises:  a ratio extraction step (222, 225), during  which one extracts, among the symbols received during  receiving step, a ratio selected by the device of  diffusion, and  an error correction step (263), during which  correcting errors affecting information symbols  primary school, during which a number of  redundancy information symbols less than or equal to  number corresponding to the selected ratio, to correct  errors affecting primary information symbols.  30. Reception method according to claim 29, characterized in that it comprises: a quality estimation step, during which a quality of transmission is estimated on said transmission medium and a transmission step, during which a signal representative of said transmission quality is sent to said broadcasting device.  31. The reception method as claimed in claim 30, characterized in that it includes a step of detecting error-affected information symbols (223, 246, 262, 263), during which each symbol of each error symbol is detected. error-informed information and in that during said quality estimation step, according to predetermined quality estimation rules, the detection of the information error information symbol information transmitted by an emission device.  32. Reception method according to any one of claims 29 to 31, characterized in that it comprises a transmission step, during which is transmitted to the broadcast device, information symbols received during of the receiving step.  33. Reception method according to any one of claims 29 to 32, characterized in that, the primary information symbol broadcasting device inserting, among transmitted protocol symbols, successive line numbers corresponding to lines of data. information symbols in a block, the receiving method comprises a transmission quality estimation step (223, 246) during which the absence of line numbers in the received information symbols is detected.  34. Reception method according to any one of claims 29 to 33 characterized in that: - it comprises a step of detecting and counting errors (223, 246), during which errors are detected and counted assigning at least one primary information symbol and providing information representative of a number of errors, and - during the error correction step, correcting the errors affecting the primary information symbols is not corrected for which the ratio selected by the broadcast device corresponds to a number of errors less than the number of errors represented by the information provided during the detection and counting step.  35. Reception method according to any one of claims 29 to 34, characterized in that it comprises, successively: the symbol receiving step (206), during which symbols are received from the device for broadcasting, symbols comprising primary information symbols and redundancy information symbols corresponding to these primary information symbols and capable of correcting errors affecting said information symbols, - an extraction step ( 202), during which, among the symbols received during said reception step, the first protocol symbols are extracted, and - a step of selecting a reception mode (241, 242, 243, 203), during which said predetermined "receiving mode selection mode" rules taking into account said first protocol symbols are used to select a reception mode among reception modes each comprising, on the part of the receiving device, no transmission of signals to the broadcasting device, until the broadcasting device has broadcast all the primary information symbols to be transmitted, the reception mode selected during the selection step being implemented during the reception step - a correction step (263) in which the error correction affecting primary information symbols is performed by setting providing redundancy information symbols received during the receiving step; - receiving step (207) of second protocol symbols, in which second protocol symbols are received; and - a reception interruption step (208), during which the reception step is interrupted, when the second protocol symbols have been received during the second symbol receiving step.  36. A network characterized in that it comprises a transmission medium, a primary information symbol broadcasting device according to any one of claims 1 to 10 and at least one primary information symbol receiving device according to the present invention. any one of claims 11 to 18, the selected ratio extracted by the extracting means of the receiving device being the ratio selected by the selection means of the broadcasting device.  37. Facsimile machine, characterized in that it comprises a receiving device according to any one of claims 11 to 18.