FR2677829A1 - MULTICHANNEL MESSAGE TRANSMISSION SYSTEM. - Google Patents

Abstract

The invention relates to a multichannel transmission system with at least one pilot transmitter (S1, S2) for transmitting messages over several channels with different transmission frequencies and several receivers (E1, E2, E3) with several reception channels. tuned to the transmission frequencies. The transmission frequencies of the transmitters and receivers are modified by switching the channels of the pilot transmitters (S1, S2) within narrow time windows, each associated with different transmission frequencies, in a significantly more frequent manner than the switching. receiver channels (E1, E2, E3). The pilot transmitters (S1, S2) each transmit a message repeatedly in different time windows with the different associated transmission frequencies. When the reception of a message has been successful, the receivers (E1, E2, E3) send a return message to the pilot transmitters (S1, S2).

Description

The invention relates to a multichannel message transmission system.

  multichannel transmission system comprising at least one pilot transmitter for transmitting messages on several transmission channels with transmission frequencies

  different each time and several receivers each provided with several

  several reception channels tuned to the transmission frequencies

  transmission frequencies of transmitters and receivers

  varying by channel switching in a time grid.

  Transmission systems of this type are used for example for the automatic transmission of radiotelegrams in information networks for remote control devices by

  radio and other multiple access devices.

  For multichannel transmissions, time multiplexing methods are known in which different partial frequency ranges are allocated to the different transmitters and time multiplexing methods in which each transmitter is assigned a single message transmission a time window

of a periodic time grid.

  Document DE-OS 35 15 127 discloses a combination of the two methods. The multichannel transmission system described in this

  document uses correlated multiple transmission, in which most

  several transmitters can transmit simultaneously, this being obtained by means of defined frequencies allocated to each of the transmitters and receivers in synchronous time windows of a time grid

  which is decisive for all transmitters and receivers Synchro-

  setting of the time windows and the time grid as well as

  frequencies is operated using one or more signal sources

  general reference for all transmitters and receivers In this system

  me of multichannel transmission, all transmitters and receivers are

  interconnected via a circuit, preferably a circuit

  power supply, but the principles stated can also be applied to radio systems, but at the cost of greater complexity, in particular because of the need to have

  independent reference issuers.

  Frequency-selective noise can decrease the

  transmission unit in the known system; these parasites can

  If all is to be eliminated, in particular by redundancy, that is to say in the present case by repeated transmission of message bits on different frequencies, for a corresponding expense.

  The objective of the present invention is to propose a system

  me of multichannel transmission of the indicated type which can be realized at

  low cost and eliminates parasites and receiving zeros.

  The problem is solved according to the invention by the fact that the

  Channel switching of the pilot transmitters takes place inside the window.

  very narrow times, each associated with transmission frequencies

  different, significantly more frequently than a com-

  receptor channel mutation, the pilot transmitters transmitting each

  cun a message repeatedly in different time windows with the different associated transmission frequencies and thereby

  that when the reception of a message has been successful, the receivers

  see a return message to the pilot transmitters with the frequency of

  corresponding transmission of the received message.

  According to the invention, the frequency channels of a pi-

  lot are switched in an orderly or statistically manner in a time grid containing several time windows, the time windows being appreciably narrower than those of receivers, whose reception channels are switched less frequently, according to a larger time grid, transmitter time grids and

  receivers not being synchronized.

  The pilot transmitter (s) repeatedly transmit within narrow time windows determined by the tight transmitter time grid, with different frequencies, messages which may be selectively addressed to of the given receivers, and receive a return message when the transmission frequency or the carrier frequency of the transmitted message coincides with the frequency determining for the receiver in the time window

  considered in this way, the period of time during which a liiai-

  message sound with a receiver can be established in a system of

  multichannel transmission comprising a plurality of transmitters and re-

  receivers is statistically the same for all receivers A sys-

  This type of transmission allows you to take advantage of the advantages of uncorrelated multichannel transmission without presenting their sensitivity to selective interference, a message that can be repeated with another frequency This also avoids receiving zeros, this is -

  i.e. cancellation of receive signal voltages by amplifiers

  signal with the same value in phase opposition, a phenomenon which is caused for example by a bi-directional propagation We thus have a frequency-efficient system presenting simultaneously a

high transmission security.

  The time windows of the transmitter time grid and the receiver time grid do not have to be

  identical to each other; we can also proceed here to a static distribution

  or you can change the channel or send

  another message as soon as the first message has been successfully transmitted

  cès a receiver An exploitation of this type saves

frequencies.

  The principle of message transmission according to the invention

  can in particular be used in automatic radio systems

  communication As an example let us quote the indication of the position

  in bus or taxi systems or in backup systems

  tage, for example in connection with satellite tracking systems

  lites or in the military field, the connection with mines, the trans-

  mission of orders issued and order receipts or information from sensors

to command centers.

  According to an advantageous embodiment of the invention, the time windows of the transmitter time grid are at least two

  times narrower than the time windows of the Avantageu-

  The width of the transmitter time windows is equal or even negligible.

  smaller than the width of the receiver time windows divided by the

  number of transmission frequencies.

  The different transmission frequencies are applied to the time windows of the transmitters in an ordered sequence or

statistically.

  In accordance with an improvement of the invention, the duration

  time windows is variable.

  The invention is described below in detail using

  of an exemplary embodiment with reference to the drawings These represent

  feel: Figure 1, a block diagram of a multichannel transmission system according to the invention comprising two pilot transmitters and three receivers each working with four carrier frequencies; Figure 2, a time grid for channel switching on different carrier frequencies in a pilot transmitter and,

  Figure 3, the corresponding time grid for a reception

  tor. In FIG. 1, the references Si and 52 designate two transmitters

  pilots each comprising an antenna 1 for transmitting and receiving

  tion with associated transmission and reception circuits El, E 2 and E 3

  designate three receivers which also each have an antenna

  ne 2 transmission and reception with corresponding transmission / reception circuits.

  Transmitters and receivers work with four frequencies

  transmission frequencies fi, f 2, f 3, f 4.

  FIG. 2 represents a series of 32 time windows 11, 12, 13, 14 of a transmitter The time windows are arranged in ZS time grids, in groups of four time windows 11, 12, 13, 14 at which transmission frequencies fl, f 2, f 3, f 4 are allocated The indicated arrangement of the time grids with the time windows is repeated at the bo of a certain period of time which varies according to

  of the type of application and is for example one hour.

  FIG. 3 represents a time grid ZE of a receiver which also consists of four time windows 21, 22, 23, 24

  for frequencies fi, f 2, f 3, f 4 This time grid is also repeated

  so at regular intervals of about an hour So the windows

  very times 21, 22, 23 and 24 of the time grid ZE on the receiver side are significantly wider than those of the time grid ZS on the side

  transmitter, eight times larger in this case.

  To establish contact between a transmitter and a receiver addressed in a selective manner, the pilot transmitter transmits the concerned message, for example a radiotelegram, repeatedly in

  the time windows given with the corresponding transmission frequencies

  respondents he repeats this until the frequency of trans-

  mission coincides with the instantaneous frequency associated with the instantaneous window on the receiver side In the case of a time grid divided into four time windows with four frequencies, a successful transmission will take place at the latest during the fourth repetition of the message. When the installation comprises several pilot transmitters and

  several receivers, these work statistically, so

  that we have an average time in which, statistically, a reception

  any author is contacted by any receiver.

  The transmitters and receivers are of common design and it is not necessary to describe them in detail The transmitter comprises for example an oscillator which can be switched on several frequencies

  carriers, four in this case, to which we send, via

  diary of a modulator, a message from a memory, the

  dulator modulating the emission oscillator according to the content of the

  message The memory for the message is connected to an

  corresponding entry from which different messages can be taken

  ges The transmission oscillator is connected to the antenna 1 The antenna is in

  additionally connected to a receiving circuit which can be arranged in form

  me of heterodyne receiver with the transmission circuit The carrier frequency of the transmission oscillator is controlled by a channel selection circuit which, in turn, is connected to a basic system of

  time which determines the duration of the different time windows The system

  time base can be connected to an output of the receiving circuit

  tion so that a change occurs in the channel as soon as a

  message has been successfully received by a receiver and the receiver has

  saw a return signal to the transmitter.

2677829 92/164

Claims (5)

  1 Multichannel transmission system comprising at least one pilot transmitter for transmitting messages on several transmission channels with different transmission frequencies each time and several receivers each provided with several reception channels tuned to the transmission frequencies, the frequencies of transmitters and receivers varying by switching of   channel in a time grid, characterized in that the switching   The channel of the pilot transmitters (Si, 52) takes place inside the window.   very short times (11, 12, 13, 14), each associated with frequencies   transmission frequencies (fl, f 2, f 3, f 4) different, significantly   significantly more frequent than a receiver channel switch   (El, E 2, E 3), the pilot transmitters (51, 52) each transmitting a message   ge repeatedly in different time windows (11, 12, 13,   14) with the different transmission frequencies (f 1, f 2, f 3, f 4) as-   companies and by the fact that, when the reception of a message was successful,   the receivers (El, E 2, E 3) send a return message to the transmitters   pilot drivers (Si, 52) with the corresponding transmission frequency te of the received message.   2 transmission system according to claim 1, character-   laughed at by the fact that the time windows (11, 12, 13, 14) of the grid   transmitter times (ZS) are at least half as wide as the fe-   time beings (21, 22, 23) of the receptors (El, E 2, E 3).   3 transmission system according to claim 2, character-   laughed at by the fact that the width of the time windows (11, 12, 13, 14) of the pilot transmitters (51, 52) is equal and more particularly less than the width of the time windows (21, 22, 23, 24) receivers (El, E 2, E 3) divided by the number of transmission frequencies (fi, f 2, f 3, f 4).   4 Transmission system according to any one of the res-   above, characterized by the fact that the different frequencies   transmission quences (fi, f 2, f 3, f 4) are applied to the windows of   time (11, 12, 13, 14) of the transmitters (SI, 52) according to a sequence or-   given. Transmission system according to any one of Claims 1 to 3, characterized in that the different transmission frequencies (fi, f 2, f 3, f 4) are applied to the time windows (11, 12, 13, 14 ) transmitters (Si, 52) statistically.   6 Transmission system according to any one of the res-   previous indications, characterized in that the duration of the windows   time (11, 12, 13, 14; 21, 22, 23, 24) may vary.