GB2290929A

GB2290929A - Facsimile interface apparatus

Info

Publication number: GB2290929A
Application number: GB9412444A
Authority: GB
Inventors: Richard John Hocking; Peter John Schwarz
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-06-21
Filing date: 1994-06-21
Publication date: 1996-01-10
Also published as: GB9412444D0

Abstract

Facsimile interface apparatus for interfacing between a modem of a locally connected facsimile machine and a telecommunications line, where the facsimile modem is operable at or up to a first data rate, enables data to be transferred via the telecommunications line at up to a second data rate higher than the first data rate. The facsimile interface apparatus comprises a facsimile interface 16 for interfacing with the facsimile modem at up to the first rate, a memory 20 connected to the facsimile interface modem for storing data received from the facsimile modem via the facsimile interface modem, or to be transmitted to the facsimile modem via the facsimile interface modem, a line interface 15 connected to the memory for interfacing with the telecommunications line 14 at up to the second data rate and a controller 22 for controlling the operation of the apparatus. By this means it is possible to reduce the length of time taken to transmit a facsimile via the telecommunications line, thereby reducing the cost of transmitting the facsimile. The facsimile interface apparatus may be provided as an add-on to a conventional facsimile machine or may be included as an integral part of a facsimile machine. <IMAGE>

Description

FACSIMILE INTERFACE APPARATUS The invention relates to the transfer of facsimile (fax) data.

Conventional Group 3 facsimile machines transmit information on analogue telephone lines using integral modems that operate at various speeds between 300 bits per second (bps) and 14,400bps.

Control information is normally transmitted at 300bps, although there is an optional 2,400bps mode. Image information is normally transmitted at either 9,600, 7,200, 4,800 or 2,400bps dependant on line quality, although the some of the latest generation of machines also support transmission at 14,400bps.

Group 4 facsimile machines are also known which are able to transmit data in digital format via 64kbps basic rate ISDN lines.

Conventional Group 3 facsimile machines are, however, unable to transmit data in such a digital format.

Because Group 3 facsimile machines contain integral modems, new facsimile machines have been designed to incorporate faster modems as the technology became available. For example, the newer 14,400bps V.17 modems have only been incorporated in the most recent facsimile machines, earlier ones being limited to a maximum transmission speed of 9,600bps.

Recently, a new generation of modem technology known as V.34 has become available with transmission speeds of up to 28,800bps. It is likely that in due course, the V.34 modem technology (or a similar technology re-engineered for facsimile operation) will become available as part of a standard facsimile machine.

However, the development of new, faster, facsimile machines does not help the owners and operators of existing Group 3 facsimile machines who, unless they invest in the new faster machines, possibly before the end of the useful life of their existing machines, are unable to benefit from the new technology. Accordingly, the inventors have recognised the problem of enabling existing Group 3 facsimile machines to take advantage of faster modem technology.

Facsimile "store and forward" systems are known in which facsimiles to be transmitted are stored in a memory before transmission to a telephone line. Such systems are typically used to provide the following services: (a) To make facsimiles available over local area networks.

(b) To provide facsimile on demand services (where callers can request information to be sent automatically by facsimile to them).

(c) To reduce costs by routing facsimiles over lower cost carriers (telephone lines) or at night when transmission costs are lower.

(d) To facilitate facsimile mailshots.

However, these systems do not provide a solution to the identified problem as they operate at the standard facsimile transmission speed and therefore do not reduce the time required to transmit the facsimile and consequently do not reduce the cost of a facsimile transmission when this cannot wait until a time when cheap rate calls are available.

Systems which provide facsimile de-modulation are also known.

Facsimile de-modulation converts analogue (telephone line) facsimile information back to its digital source (modulation is the reverse process). If transmitted at 9,600bps, the de-modulated digital information will carry the facsimile image at normal transmission speed. Analogue facsimile information may also be converted into digital information (digitised) without using de-modulation. In this case however, the digitised information requires 64,000bps to carry the facsimile image at normal transmission speed. Because a demodulated facsimile image only requires 9,600bps whereas a digitised facsimile image requires 64,000bps, facsimile de-modulation is often described as facsimile compression.Commercially available facsimile de-modulation systems are used to carry multiple 9,600bps facsimile messages simultaneously on a single 64,000bps digital line. Thus conventional facsimile de-modulation systems make more efficient use of a digital line by sharing it among multiple facsimile machines.

They do not reduce the time required to transmit a facsimile message and thus do not reduce the cost of a facsimile transmission on an analogue line or on a digital line which is onl used for one facsimile transmission at a time.

In accordance with the invention, there is provided a facsimile interface apparatus for interfacing between a modem of a locally connected facsimile machine and a telecommunications line, wherein the facsimile modem is operable at up to a first data rate, said facsimile interface apparatus comprising a facsimile interface for interfacing with the facsimile modem at up to said first rate, a memory connected to said facsimile interface for storing data received from said facsimile modem via said facsimile interface, or to be transmitted to said facsimile modem via said facsimile interface and an interface, hereinafter called an external interface, connected to said memory for interfacing with said telecommunications line at or up to a second data rate higher than said first data rate.

The invention enables a conventional facsimile machine to take advantage of transmission rates faster than that for which it was designed, enabling phone call costs of using a standard Group 3 facsimile machine, for example, to be reduced. By using the interface apparatus in accordance with the invention at a rate faster than that of the facsimile machine and using the interface apparatus to provide the actual connection to the telephone lines, the length of time required for the actual transmission over the telecommunications line can be reduced.

In the present description, reference is be made to telephone and telecommunication lines. However, it is to be appreciated that the invention is not limited to the use of conventional subscriber telephone lines, but includes transmission by other telecommunications media, such as for example, cellular telephone connections, cable television lines, etc.

In one embodiment the facsimile interface and the external interface use one set of modems shared between them. In this embodiment, the apparatus comprises a plurality of modems operable at data rates lower than said second data rate, a further, high speed, modem operable at said second data rate and switch means for selectively switching one of said first plurality of modems to said facsimile line interface or to said external line interface and for selectively connecting said further modem to said external line interface. This enables the invention to be implemented with a lower expenditure on hardware and/or software by selectively switching the modems to the facsimile machine or telecommunications line sides.

Alternatively, however, the apparatus could be implemented such that said facsimile interface comprises a plurality of facsimile interface modems operable at data rates lower than said second data rate and said external interface comprises a second plurality of modems operable at data rates lower than said second data rate and a further, high speed, modem operable at said second data rate.

Preferably said plurality of modems operable at data rates lower than said second rate are operable at one or more of the following data transmission rates: 14,400, 9,600, 7,200, 4,800, 2,400 and 300bps. In a particular embodiment of the invention, said high speed modem is a V.34 type modem operable at 28,800bps.

Preferably, said external interface comprises a digital line interface for digital transmission and/or reception via said telecommunications line and/or an analogue line interface for analogue transmission and/or reception via said telecommunications line.

By arranging that said facsimile interface apparatus emulates a remote facsimile machine during data transfer between said memory and said facsimile modem, the existence of the facsimile interface apparatus is transparent to the locally connected modem.

In order to enable data to be received by the facsimile interface apparatus at one rate and output at another rate, data is arranged to be buffered in said memory between local and remote data transfers, that is between the transfer of data from said facsimile modem and the transfer of data to said telecommunications line and between the transfer of data from said telecommunications line and the transfer of data to said facsimile modem.

By buffering facsimile data and control data, the control data overhead normally present in facsimile transmission, as a result of sending control data at low speed, can be minimised if the control data is sent as part of a package of data transmitted to the remote station at high speed by the facsimile interface apparatus. If desired, additional error detection and/or correction data could be computed and sent with the image and control data via the telecommunications line to enable enhanced error discovery and/or recovery-at the remote station.

The facsimile interface apparatus can be provided with data encryption means for encrypting facsimile data for transmission via said line interface to said telecommunications line and/or data decryption means for decrypting encrypted facsimile data received via said line interface from said telecommunications line.

The invention also provides a facsimile machine comprising scanner and printing means, a modem operable at up to a first data rate and a facsimile interface apparatus as defined above.

Exemplary embodiments are described hereinafter, by way of example only, with reference to the accompanying drawings in which: Figure 1 represents an illustrative arrangement of a first and a second facsimile interface apparatus in accordance with the invention, each located between a respective first and second conventional Group 3 facsimile machine and a telephone line; Figure 2 is a block diagram of a first embodiment of a facsimile interface apparatus in accordance with the invention; Figure 3 is a block diagram of a second embodiment of a facsimile interface apparatus in accordance with the invention; and Figure 4 is a block diagram of a third embodiment of a facsimile interface apparatus in accordance with the invention.

Figure 1 represents schematically the application of an example of a facsimile interface apparatus 10 in accordance with the invention to interconnect two facsimile machines 12A and 12B via a telecommunications line, for example an external telephone line 14.

Each of the two facsimile interface apparatus lOA and lOB is connected between a respective one of first and second conventional Group 3 facsimile machines 12A and 12B and the telephone line 14. In this example, the facsimile interface apparatus in accordance with the invention enables the telephone call costs of transmitting a facsimile using a standard Group 3 facsimile machine to be reduced by using a faster transmission rate which reduces the length of time required to transmit the facsimile over the telephone line.

Figure 2 illustrates one facsimile interface apparatus 10 for use as the apparatus lOA or lOB in Figure 1. A first side of the facsimile interface apparatus 10 is provided with a facsimile interface including a set 16 of conventional Group 3 facsimile modems, such as V.21, V.27ter, V.29 and V17 modems, as would be found in a conventional Group 3 facsimile machine, a switch 26 and an analogue line interface 13. The switch 26 is used to connect an appropriate modem to the analogue line interface 13. This first side of the apparatus 10 enables connection of the apparatus 10 to the facsimile interface of the Group 3 facsimile machine 12A/B. The first side of the apparatus 10 operates at the standard transmission rate(s) for the Group 3 facsimile machine 12A/12B.

A second side of the apparatus 10 is provided with an external interface for connection to the telephone line 14 including a group of modems 17, having a set 16 of Group 3 facsimile modems and one or more high speed modem(s) 18, a switch 28 and an analogue and/or digital line interface 15. The modems of the second side are only used when transmission or reception is via an analogue line interface 15. When transmission of reception is via a digital line interface the modems on the second side are by-passed by means of the switch 28 and the line 30.

By the provision of the high speed modem 18, the second side of the apparatus 10 is able to operate at a higher rate than the first side via an analogue line interface 15. Similarly, higher transmission or reception speeds than are possible via the first side can be achieved by means of a digital interface for the transmission of data over, for example an ISDN (Integrated Subscribers Digital Network) line.

Thus, the second side provides a high speed external interface including a digital line interface or a high speed modem such as V.32terbo or V.34 with an analogue line interface for a conventional analogue telephone line, or an interface providing data compression to reduce the quantity of data to be transmitted (not shown), or by some combination of the above. Thus the data can be transmitted over the telephone line using a high speed transmission format for interfacing directly with a compatible high speed remote station or another facsimile interface apparatus.

A memory 20 is used for the temporary storage of data within the apparatus 20 under the control of a controller 22 which is connected via control paths (shown dashed) to the other elements of the apparatus 10 including the switches 26 and 28. The switches 26 and 28 are controlled in a substantially conventional manner in response to control information sent between facsimile machines, with the switch 28 also being controlled to provide an appropriate connection via the line 30 during digital transmissions.

Because the facsimile machines 12A/12B transmit and receive data at a slower rate than that at which the V.34 modem 18 or ISDN interface 15 transmits and receives data over the telephone line 14, it is necessary for the source facsimile machine 12A/12B to initially transfer the facsimile to be transmitted to the memory 20 within the apparatus 10. The controller 22 is operative to cause the facsimile interface to emulate a remote facsimile machine so that the locally connected facsimile machine thinks that it is communicating via a telephone line to a remote facsimile machine. However, during this time the apparatus 10 is not in fact transmitting to the telephone line, so no call charges are incurred.After the controller 22 has detected from the standard facsimile protocol information that the facsimile data has finished being transferred from the local facsimile machine to the local apparatus memory 20, the controller 22 automatically dials the required number and connects the apparatus 10 via the telephone network to remote matching equipment, for example an identical or similar facsimile interface apparatus. The facsimile is then transmitted from the local store 20 at high speed, received and stored by the remote apparatus, and subsequently transferred at low speed to the second facsimile machine.

Thus, in operation a facsimile to be transmitted from the facsimile machine 12A is transmitted to the facsimile interface apparatus lOA at low speed where it is demodulated by the facsimile interface modems in the facsimile interface and stored in demodulated form in the memory 20. The facsimile is then passed at high speed via the external interface to the telephone line 14. If the data is to be transmitted in analogue form via the telephone line 14, it is modulated by, for example, a high speed V.34 modem 18 and is then passed via an analogue line interface 15. If the data is to be transmitted in digital form via the telephone line 14, this can be effected by by-passing the group of modems 17 (via the line 30 and the switch 28) and then using, for example, an ISDN line interface 15.

On receipt at the remote facsimile interface apparatus lOB, the received data is demodulated by, for example, a V.34 modem 18 or received by, for example, an ISDN line interface 15 according to the telephone line transmission standard and stored in the memory 20 of the remote facsimile interface apparatus lOB. From there it is passed to the remote facsimile machine 12B at low speed via the facsimile interface of the remote apparatus 10.

If V.34 modem technology is used for the high speed modem 18 in the external interface for an analogue line to modulate the previously de-modulated digital information from the facsimile interface, a maximum transmission speed of 28,800bps can be achieved via the telephone line. For a digital line, any speed is possible, limited only by the transmission speed of the line. For example, a basic rate ISDN line would carry 64,000bps per channel.

The internationally agreed protocol that governs the operation of facsimile machines requires control information to be sent at low speed between every page. For standard facsimile machines this adds an overhead to the time required to send a multi-page facsimile. However, where the remote equipment is compatible with the local apparatus 10, the control information may be sent at high speed between the interface apparatus lOA and lOB. Thus, although during the transfer phase from the source facsimile machine to the local apparatus, the standard protocol will be employed, including the slow speed control information, during the subsequent transmission to the remote equipment, the entire stored message including both the slow control information and the image data, will all be transmitted at high speed.Accordingly, the invention will not propagate the overhead caused by the transmission at low speed of the control information. This has the effect of further reducing the transmission time required for a multi-page facsimile message.

Particularly where the control data is sent at high speed, the controller 22 could compute additionally error detection and/or correction data using conventional algorithms as will be known to the skilled person and send these with the image and control data via the telephone line. The controller 22 of a receiving facsimile interface apparatus would then provide corresponding error detection and/or correction of the received data in an appropriate manner.

The apparatus 10 is preferably arranged to permit a local facsimile machine/apparatus combination to interwork fully and normally with non-equipped remote facsimile machines. In this case however, the transmission rate would be limited by the non-equipped facsimile machine and consequently there might not be a reduction in transmission time depending on the maximum speed of operation of the receiving facsimile machine.

Thus, in the above embodiment, the Group 3 modems 16 in the group 17 of modems will be used for external transfer instead of the high speed modem 18 where the line quality or the remote facsimile is unable to support high speed transmission. This embodiment of the invention thus enables downward compatibility with remote facsimile machines.

In the above described embodiment of the invention, therefore, the apparatus interfaces externally to a standard facsimile machine, and appears to that machine to be a conventional remote facsimile machine. The equipment de-modulates the facsimile modem information into equivalent digital information which it stores in memory. The stored digital information is then modulated by a V.34 modem within the apparatus and transmitted to the telephone line or alternatively, the information is transmitted to a digital ISDN line.

Compared with using a higher speed integral modem, the invention eliminates the requirement to design or purchase a new facsimile machine, and reduces the overall transmission time by reducing the inter-page control message overhead.

As an alternative to providing the apparatus 10 as an add-on to an existing facsimile machine, the apparatus 10 could be built into a facsimile machine. In this case it would not be necessary to completely redesign an existing facsimile machine, providing the advantage that high speed telephone line transmission would be possible without the need to provide high speed image scanning mechanism and/or printing.

Figure 3 illustrates a development of the apparatus of Figure 2 to additionally provide for the encryption/decryption of facsimile data. Only the significant differences between this embodiment and Figure 2 embodiment will be highlighted in the following description of Figure 3, features and aspects not explicitly described being assumed to be substantially as for the Figure 2 embodiment.

Once facsimile information has been de-modulated to digital information, it is relatively simple to incorporate encryption. By providing encryption, CRYPTO 24, between the facsimile interface and the external interface, that is between the output of the internal facsimile de-modulator 16 and the input of the V.34 modem 18 or ISDN transmitter 15 as shown in Figure 3, data transmitted to the telephone line 14 can be encrypted.

Likewise, data decryption CRYPTO 24 can be provided between the external interface and the facsimile interface, that is between the output of the V.34 modem 18 or ISDN receiver 15 and the input to the internal facsimile modem(s) 16 of the facsimile interface, in order to decrypt encrypted information received from the telephone line 14. The data encryption and/or decryption can be provided after receipt and before storage in the memory 20, after retrieval from the memory 22 for further transmission, or as a result of retrieving the information from the memory 20, performing the data encryption or decryption and storing the processing data back in the memory 20. The data encryption and/or decryption can be provided by means of dedicated hardware or software, or a combination of both, and using standard encryption algorithms as will be apparent to one skilled in the art.

By the additional provision of data encryption/decryption, data transmitted via the telephone line can be effected with the twin benefit of reduced facsimile transmission costs together with security.

Figure 4 is an alternative embodiment of a Group 3 interface apparatus 10 in accordance with the invention which corresponds generally to, but is structured differently from the one shown in Figure 2.

It will be noted in the embodiment of Figure 2, and also that of Figure 3, that the set of Group 3 modems 16 is duplicated. Figure 4 takes advantage of this by providing one group of modems corresponding to the group of modems 17 (including the set of Group 3 modems 16 and the high speed modem 18) common to both the first and second sides of the apparatus 10 and a switch 32 enabling analogue transmission from and reception by the modems selectively via the facsimile interface 13 and the external line interface 15. A further switch 34 is connected directly between the memory 20 and the external line interface 15 selectively for enabling digital transmission and reception via the external line interface 15.A further switch or switches (not shown) enable the connection of an appropriate modem in the group 17 of modems for connection to the analogue line interfaces 13 and 15. The switches 32, 34 and the further switch(es) are controlled by the controller 22 via the control lines represented schematically by dashed lines in Figure 3. The switches 32 and 34 are controlled by the controller in response to control signals received from the analogue line interface 13 and the analogue/digital line interface 15.

The analogue line interface 13 in this embodiment, as in the other embodiments, includes a dialling/hook detector for detecting an outgoing transmission. In response to the detection of an outgoing transmission from the local facsimile machine 12, or on the termination of an incoming transmission from the line 14, the switch 32 and the further switch(es) (not shown) are controlled by the controller 22 to connect the set of Group 3 modems 16 to the line interface 13. This connects the memory 20 via those modems 16 to the line interface 13.

The analogue line interface 15 in this embodiment, as in the other embodiments, includes a ringing detector. In response to the detection of an incoming analogue transmission from the line 14, or on the termination of an outgoing transmission from the line 12 to be transmitted in analogue form, the switch 32 and the further switch(es) (not shown) are controlled by the controller 22 to connect the group of modems 17 including the high speed modem 18 to the line interface 15. This connects the memory 20 via those modems 16 and 18 to the line interface 15. In response to the detection of an incoming digital transmission from the line 14, or on the termination of an outgoing transmission from the line 12 which is to be transmitted in digital form, the switch 34 is controlled by the controller 22 to connect the memory 20 directly to the line interface 15.

In this manner, the embodiment of Figure 4 can be implemented at lower cost by using a single set of Group 3 modems for both internal and external data transfer (not simultaneously), it being understood the Group 3 modems 16 will be used for external transfer instead of the high speed modem 18 where the line quality or the remote facsimile is unable to support high speed transmission. This embodiment of the invention thus enables downward compatibility with remote facsimile machines.

A disadvantage of implementing the apparatus with shared modems as in Figure 4 is that overlapping operation of the facsimile and external interfaces is difficult to implement as the reception of data via the modems into the memory needs to be completed before the transmission from the memory via the modems can be effected. With separate modems in the facsimile interface and the external interface as shown in Figures 2 and 3 overlapping operation can be achieved through the use, for example, of a dual port memory 20.

It will be appreciated that the structure of the embodiment of Figure 3 could also be modified to correspond generally to the structure of the embodiment of Figure 4.

Although the invention has been described with reference to specific examples, it will be appreciated that modifications and/or additions are possible within the scope of the invention.

Thus an embodiment of the invention enables the transmission of a single facsimile at high speed via a conventional analogue telephone line and/or alternatively via a high speed digital telephone line (e.g., a 64kbps basic rate ISDN line) using conventional facsimile machine technology such as Group 3 facsimile machines. A single facsimile message can thus be transmitted at the maximum available speed on the telephone line, whether analogue or digital.

Also, although reference has been made to using high speed V.34 type modem technology, the invention is also applicable for use with any other high speed modem technology for interfacing with a telecommunications line or connection.

Claims

1. Facsimile interface apparatus for interfacing between a modem of a locally connected facsimile machine and a telecommunications line, wherein the facsimile modem is operable at up to a first data rate, said facsimile interface apparatus comprising a facsimile interface for interfacing with the facsimile modem at up to said first rate, a memory connected to said facsimile interface for storing data received from said facsimile modem via said facsimile interface, or to be transmitted to said facsimile modem via said facsimile interface and an external interface connected to said memory for interfacing with said telecommunications line at or up to a second data rate higher than said first data rate.

2. Apparatus according to claim 1 comprising a plurality of modems operable at data rates lower than said second data rate, a further, high speed, modem operable at said second data rate and switch means for selectively switching one of said first plurality of modems to said facsimile line interface or to said external line interface and for selectively connecting said further modem to said external line interface.

3. Apparatus according to claim 1, wherein said facsimile interface comprises a plurality of facsimile interface modems operable at data rates lower than said second data rate and said external interface comprises a second plurality of modems operable at data rates lower than said second data rate and a further, high speed, modem operable at said second data rate.

4. Apparatus according to claim 2 or claim 3, wherein said plurality of modems operable at data rates lower than said second rate are operable at one or more of the following data transmission rates: 14,400, 9,600, 7,200, 4,800, 2,400 and 300bps.

5. Apparatus according to any one of claims 2, 3, and 4, wherein said high speed modem is a V.34 type modem operable at 28,800bps.

6. Apparatus according to any one of the preceding claims, wherein said external interface comprises a digital line interface for digital transmission and/or reception via said telecommunications line and/or an analogue line interface for analogue transmission and/or reception via said telecommunications line.

7. Apparatus according to any one of the preceding claims, wherein said facsimile interface emulates a remote facsimile machine during data transfer between said memory and said facsimile modem.

8. Apparatus according to any one of the preceding claims, wherein data is arranged to be buffered in said memory between the transfer of data from said facsimile modem and the transfer of data to said telecommunications line and between the transfer of data from said telecommunications line and the transfer of data to said facsimile modem.

9. Apparatus according to claim 8 wherein said buffered data comprises facsimile data and control data.

10. Apparatus according to any one of the preceding claims comprising a data encryption means for encrypting facsimile data for transmission via said external interface to said telecommunications line and/or data decryption means for decrypting encrypted facsimile data received via said external interface from said telecommunications line.

11. A facsimile machine comprising scanner and printing means, a modem operable at up to a first data rate and apparatus according to any one of the preceding claims.

12. A facsimile interface apparatus substantially as hereinbefore described with reference to the accompanying drawings.

13. A facsimile machine comprising facsimile interface apparatus substantially as hereinbefore described.