Device and method for the data transmission or storage optimizing the use of the pass-band

• US 5,271,043 A
• Filed: 11/08/1991
• Issued: 12/14/1993
• Est. Priority Date: 10/07/1986
• Status: Expired due to Fees

• Current Assignee: Thomson-CSF
• Original Assignee: Thomson-CSF
• Inventors: Auvray, Gerard, Anastassiades, Jean, Elleaume, Philippe, Desodt, Guy, Fouche, Yvon
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): Bocure, Tesfaldet
• Application Number:
  US07/790,645
• Time in Patent Office: 767 Days
• Field of Search: 375/115, 375/4, 375/96, 375/38, 375/22, 375/23, 370/107, 390/825.03, 390/825.64, 332/120, 332/145, 380/15, 358/120, 455/102
• US Class Current: 375/367
• CPC Class Codes: H04B 7/005 Control of transmission; Equalising
• CPC Class Codes: H04L 27/18 Phase-modulated carrier systems, i.e. using phase-shift keying H04L27/32 takes precedence
• CPC Class Codes: H04N 21/2383 Channel coding or modulation of digital bit-stream, e.g. QPSK modulation arrangements for detecting or preventing errors in the information received by adapting the channel coding H04L1/0009; analogue front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/4382 Demodulation or channel decoding, e.g. QPSK demodulation analog front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002

Abstract

A device and a method for the transmission or storage of data optimizing the use of the pass-band. Also, a method for transmission by phase modulation. In order to obtain high data throughput rates, the synchronization of a transmission clock with the reception clocks is used. This synchronization is gotten, for example, by transmission of a pseudo-random code and by the convolution or correlation of the received signals with the pseudo-random code. The invention also enables the elimination of multiple echoes by computation. The invention can be applied chiefly to the transmission of radio programs, television broadcasts or digital data.

Claims

1. A method for data transmission, from a transmitter towards at least one receiver, comprising, using similar code generators in the transmitter and in the receiver, and in said transmitter, the steps of:

phase modulating a data signal to be transmitted;

superimposing onto the phase modulated data signal a signal having an amplitude lower than the amplitude of the phase modulated data signal for synchronization of said receiver, said signal for synchronization having a period longer than a period of said phase modulated data signal and modulating in amplitude said phase modulated data signal; and

transmitting said amplitude and phase modulated data signal.

2. A method according to claim 1, wherein said signal for synchronization comprises a code from a known code generator by said at least one receiver said method comprising in each of said at least one receiver, the steps of:

amplitude demodulating said signal for the synchronization;

extracting the superimposed synchronization signal;

producing synchronization spikes, by computing the correlation and/or the convolution of said signal for the synchronization with said code known by said at least one receiver.

3. A method according to claim 2, wherein said code is a pseudo-random code.

4. A method according to claim 2 or 3, wherein said step of producing synchronization spikes comprises the steps of:

synchronizing a clock signal with the sampling frequency of said signal for synchronization;

phase synchronizing said clock signal with said phase modulated data signal, by shifting said code in respect to said phase modulated data signal.

5. A method according to claim 4, wherein said signal for synchronization further comprises data complementary to said data signal.

6. A method according to claim 5, in which said data signal is a television signal, wherein said data complementary to said data signal comprises data which, after numerical video processing, improves the quality of received images.

7. A method according to claim 6, wherein said signal for synchronization comprises first transitions, occurring at instants evenly distributed in time, and second transitions, occurring at instants of time constituting the encoding of the information to be transmitted.

8. A method according to claim 7, characterized in that said method is used for the transmission of at least one type of transmission selected among the group comprising:

television broadcasting;

radio sound broadcasting;

alphanumeric data transmission.

9. A method according to claim 3, wherein said signal for the synchronization further comprises data complementary to said data signal.

10. A method according to claim 9, in which said data signal is a television signal, wherein said data complementary to said data signal comprises data which, after numerical video processing, improves the quality of received images.

11. A method according to claim 1, wherein said signal for synchronization comprises first transitions, occurring at instants evenly distributed in time, and second transitions, occurring at different instants of time constituting the information to be transmitted.

12. A method according to claim 1, characterized in that said method is used for the transmission of at least one type of transmission selected from the group comprising:

television broadcasting;

radio broadcasting;

alphanumeric data transmission.

13. A transmitter of a data signal, comprising:

a source of data signal;

means for phase modulation of said data signal;

means for generating a code with a synchronization period longer than a period of the data signal; and

means for amplitude modulation of the phase modulated data signal in accordance with the generated code and with an amplitude lower than the amplitude of the phase modulated data signal.

14. A transmitter according to claim 13, further comprising pulse compression means for receiving said phase and amplitude modulated signal, and for pulse compressing said signal whereby, permitting an increase the signal/noise ratio.

15. A transmitter according to any of claims 13 or 14, further comprising control center receiving the compressed signal and means for distribution of data to be transmitted to a plurality of transmission channels.

16. A transmitter according to claim 15, wherein said control center is digital.

17. A transmitter according to claim 14, characterized in that said transmitter is used for the transmission of at least one type of broadcast of the group comprising:

television broadcast;

radio broadcast;

alphanumeric data transmission.

18. A receiver of a data amplitude and phase modulated signal, comprising:

means for receiving a signal having an amplitude modulated synchronization and a phase modulated data;

means for amplitude demodulation of said signal for synchronization;

means for generating a code;

means for computing the convolution and/or the correlation of said signal for synchronization with said code, producing synchronization spikes;

means for phase demodulation of said data from said signal, and

wherein said signal for synchronization has a longer period than a period of the phase demodulated data signal.

19. A receiver according to claim 18 wherein said means for computing comprises convolution means and correlation means, said convolution means realizing a first synchronization of said receiver, and said correlation means for realizing a fine synchronization of said receiver.

20. A receiver according to claim 18 or 19, wherein said means for computing the convolution and/or the correlation comprises convolution means (132), with a charge transfer device having at least one cell at an output of said charge transfer device, said at least one cell providing said code.

21. A receiver according to claim 20, comprising processing means for eliminating multiple-echoes by subtracting them from a received direct signal or by delaying them from the received direct signal so as to put them in modulo 2π

phase with the direct signal.

22. A receiver according to claim 21, wherein said processing means resolves the system:

##EQU7## a₁ representing the complex amplitude of the first reflected signal, a₂ that of the second reflected signal, a₃ that of the third reflected signal, a_i that of the i^th reflected signal, a_n representing the amplitude of the direct signal, Y_n+i being the signal received at the instant n+i.

23. A receiver according to claim 22, wherein said processing means comprises a programmable digital filter.

24. A receiver according to claim 23, further comprising a random-access video memory means (24) for storing video signals and address processor means (22) for replacing data stored in said random-access video memory by newly received transmitted data.

25. A receiver according to claim 24, wherein said random-access video memory (24) means capable of storing at least one video image, and further comprising a computer (23) connected to said memory means (24), said computer being capable of modifying all or a part of said image stored in said random access video memory means, in respect to complementary data transmitted by said signal for the synchronization.

26. A receiver according to claim 25, further comprising a frequency reduction device (82) including a timer, said frequency reduction device being connected to an input of the receiver and to a receiving antenna.

27. A receiver according to claim 26, characterized in that said receiver is used for the reception of at least one type of broadcast selected from the group consisting of:

television broadcasts;

radio broadcast;

alphanumeric data transmission.

28. A receiver according to claim 18, comprising processing means capable of eliminating multiple-echoes by subtracting them from the signal or by delaying them so as to put them in modulo 2π

phase with the direct signal.

29. A receiver according to claim 28, wherein said processing means resolves the system:

##EQU8## a₁ representing the complex amplitude of the first reflected signal, a₂ that of the second reflected signal, a₃ that of the third reflected signal, a_i that of the i^th reflected signal, a_n representing the amplitude of the direct signal, Y_n+i being the signal received at the instant n+i.

30. A receiver according to any of claims 28 or 29, wherein said processing means comprises a programmable digital filter.

31. A receiver according to claim 18, comprising random-access video memory (24) means for storing video signals and address processor means for replacing data located in said random-access video memory by newly received transmitted data.

32. A receiver according to claim 18, wherein said random-access video memory (24) means stores at least one video image, and further comprising a computer (23) connected to said memory means (24), said computer being capable of modifying all or a part of said image stored in said random access video memory means, in respect to complementary data transmitted by said signal for the synchronization.

33. A receiver according to claim 18, comprising a frequency reduction device (82) including a timer, said frequency reduction device being connected to an input of the receiver and to a receiving antenna.

34. A data transmission device comprising a transmitter and a receiver;

wherein said transmitter includes;

a source of data signal;

means for phase modulation of said data signal;

means for generating a code;

means for amplitude modulation of the phase modulated data signal in accordance with the generated code; and

means for transmitting said amplitude phase modulated signal,

and wherein said receiver includes;

means for receiving said amplitude and phase modulated data signal;

means for the amplitude demodulation of said signal;

means for generating a code identical to said code of said transmitter;

means for computing the convolution and/or the correlation of said signal for synchronization with said code, producing synchronization spikes;

means for the phase demodulation of said data signal.