Data transmission system

• US 3,885,217 A
• Filed: 07/11/1973
• Issued: 05/20/1975
• Est. Priority Date: 07/11/1973
• Status: Expired due to Term

• Current Assignee: Roberto Cintron
• Original Assignee: Roberto Cintron
• Inventors: Cintron, Roberto
• Primary Examiner(s): Safourek, Benedict V.
• Application Number:
  US05/378,190
• Time in Patent Office: 678 Days
• Field of Search: 178/5.6,DIG.23,5.1 179/1.5R,1.5C,1.5M,15BA,15BL,15BT 340/173A 360/18 325/32,38,41,42,66,311,26
• US Class Current: 375/269
• CPC Class Codes: H04H 20/31 using in-band signals, e.g. subsonic or cue signal
• CPC Class Codes: H04N 7/08 Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band , e.g. by time division H04N7/007 takes precedence
• CPC Class Codes: H04N 7/081 the additional information signals being transmitted by means of a subcarrier
• CPC Class Codes: H04N 7/16 Analogue secrecy systems; Analogue subscription systems

Abstract

A data transmission system wherein data is superposed on program material with a signal level which is in the noise range. The data is '"'"''"'"''"'"''"'"'synchronous'"'"''"'"''"'"''"'"' and at the receiving end, the data is synchronously sampled so as to extract same from the program material. The extracted data is then processed so as to, for example, identify the program source material. By using this method, data is superposed on program source material in such a manner that it may be extracted at a receiver without degrading the quality of the program source material.

Claims

1. A data transmission system for transmitting data in conjunction with a program source material signal comprising:

means for repetitively superposing the same data signal on the program source material signal to form a combined signal, said data signal being synchronous with a given frequency and having an amplitude level within the amplitude range of the ambient noise appearing in said program source material signal;

means for transmitting said combined signal;

means for receiving and operating on said combined signal to extract said data signal from said combined signal, said receiving means comprising;

synchronous sampling means for amplitude sampling said combined signal in synchronism with the synchronous frequency of said data signal;

generating means coupled to said synchronous sampling means for generating signals corresponding to the amplitude values of respective samples of said data signal;

storage means;

arithmetic means coupled to said storage means and to said generating means for adding the amplitude value of a sample corresponding to a given portion of the data signal received from said generating means with the algebraic sum of the sample amplitude values corresponding to the previous occurrences of said given portion of the data signal during the previous repetitive occurrences of said data signal, said algebraic sum being received from said storage means, and for storing the resulting algebraic sum values of said samples in said storage means;

means coupled to said storage means and responsive to said sum values of said data signal samples reaching a predetermined level for indicating the presence of valid data; and

output utilization means for generating a representation corresponding to said valid data.

2. A data transmission system according to claim 1 wherein means for superposing said data signal on said source material signal comprises means for generating a data signal which includes a repetitively generated group of signals.

3. A data transmission system according to claim 2 wherein said data signal generating means includes means for generating said group of signals which include a group of digital data signals, said group forming a data unit, said data unit being repetitively and sequentially superposed on said program source material signal.

4. A data transmission system according to claim 3 wherein said data signal generating means includes means for generating said digital signals having a frequency in the audio range, and wherein said program souce material is in the audio range.

5. A data transmission system according to claim 3 wherein said data signal generating means includes means for generating said group of digital data signals which include a plurality of signals selectively having an amplitude of a predetermined level 1 and an amplitude at a second predetermined level 0 which is lower than said first predetermined level so as to enhance synchronous sampling at said receiving means.

6. A data transmission system according to claim 1 wherein said means for repetitively superposing said same data signal on said program souce material comprises:

synchronous clock means for generating a clock signal having a predetermined frequency and which is synchronous with said given frequency;

means for generating coding signals; and

Encoding means responsive to said coding signals and to said clock signal for generating serially encoded data signals.

7. A data transmission system according to claim 6 wherein said superposing means further includes means responsive to said generating means and to said program source material signal for mixing said serially encoded data signals with said program source material signal.

8. A data transmission system according to claim 7 wherein said mixing means includes level control means for mixing said signals such that the data signal is about 40 Db below the amplitude level of program source material signal.

9. A data transmission system according to claim 1 wherein said synchronous sampling means includes means for generating a synchronized clock signal and a sample and hold circuit means responsive to said synchronized clock signal and to said combined signal for sampling said combined signal.

10. A data transmission system according to claim 9 wherein said synchronized clock signal generator includes means responsive to an external synchronizing signal for generating said synchronized clock signal.

11. A data transmission system according to claim 9 wherein said synchronized clock signal generating means include a band-pass filter means for filtering a predetermined frequency signal from said combined signal, said predetermined frequency corresponding to the synchronous frequency of said data signal;

a controlled oscillator responsive to the output of said band-pass filter for generating a synchronizing signal; and

means responsive to said synchronizing signal for generating said synchronized clock signal.

12. A data transmission system according to claim 1 wherein said receiving means includes variable gain amplifier means coupling said combined signal to said synchronous sampling means.

13. A data transmission system according to claim 12 wherein said variable gain amplifier means comprises a logarithmic amplifier.

14. A data transmission system according to claim 1 wherein said synchronous sampling means includes means for generating a synchronized clock signal of a first predetermined frequency, and a means for generating a synchronized clock signal of a second frequency substantially higher than said first frequency;

and means for selectively sampling said combined signal at one of said frequencies.

15. A data transmission system according to claim 14 wherein said synchronous sampling means includes means for sampling said combined signal at said second frequency to detect a peak value of a data bit which is part of said data signal.

16. A data transmission system according to claim 15 wherein said synchronous sampling means includes means responsive to said peak value detecting means for detecting the phase of the peak value of the data bit;

and means for correcting the phase of said synchronized clock signal of said first predetermined frequency as a function of the phase of the peak value of the data bit.

17. A data transmission system according to claim 1 comprising an analog-to-digital converter means coupled between said sampling means and said storage means.

18. A data transmission system according to claim 1 comprising an analog-to-digital converter coupling the output of said sampling means to said arithmetic means.

19. A data transmission system according to claim 1 wherein said means responsive to said sum values for indicating the presence of valid data comprises a digital comparator for comparing a sum value with a predetermined level;

and shift register means coupled to the output of said comparator for storing valid data output from said digital comparator.

20. An encoding device for repetitively superposing an audio frequency data signal on an audio program source material signal to form a combined signal comprising:

means for generating a synchronous clock signal which is synchronous with a given frequency;

means for generating data signals correspondinG to data;

modulator means coupled to said data signal generating means and to said clock signal generating means, and responsive to said data signals and synchronous clock signal for generating a synchronous modulated data signal which is modulated in accordance with said data signal; and

mixing means for mixing the output of said modulator means and said audio program source signal for producing a combined signal of said data and said audio program source signal, said modulated data signal having an amplitude level within the amplitude range of the ambient noise appearing in said audio program source signal.

21. An encoding device according to claim 20 wherein said mixing means includes means for adjusting the amplitude level of said modulated data signal such that the amplitude level of said modulated data signal is about 40 Db below the level of said audio program source signal.

22. An encoding device according to claim 20 wherein said data signal generating means includes means for repetitively generating a group of data signals, said repetitively generated group of data signals being successively superposed on said audio program source signal.

23. An encoding device according to claim 20 including encoding means for encoding said data and for generating a serial string of encoded data.

24. A data transmission system according to claim 20 including means for repetitively superposing said data signal on said program source material comprising:

synchronous clock means for generating a clock signal having a predetermined frequency and which is synchronous with said given frequency;

means for generating coding signals; and

encoding means responsive to said coding signals and to said clock signal for generating serially encoded data signals.

25. A data transmission system according to claim 20 wherein said means for generating said data signals includes means for generating digital data signals which include a plurality of signals selectively having an amplitude of a first predetermined level 1 and an amplitude of a second predetermined level 0 which is lower than said first predetermined level.

26. Apparatus for receiving and operating on a combined signal which includes repetitive synchronous data signal unit superposed within the amplitude range of the ambient noise existing in an audio program source material signal to extract said data signal from said combined signal, comprising:

synchronous sampling means for amplitude sampling said combined signal in sychronism with the data signal;

generating means coupled to said synchronous sampling means for generating signals corresponding to the amplitude values of respective samples of said data signal;

storage means;

arithmetic means coupled to said storage means and to said generating means for adding the amplitude value of a sample corresponding to a given portion of the data signal received from said generating means with the algebraic sum of the sample amplitude values corresponding to the previous occurrences of said given portion of the data signal during the previous repetitive occurrences of said data signal, said algebraic sum being received from said storage means, and for storing the resulting algebraic sum values of said samples in said storage means;

means coupled to said storage means and responsive to said sum values of said data signal samples reaching a predetermined level for indicating the presence of valid data; and

output utilization means for generating a representation corresponding to said valid data.

27. A data transmission system according to claim 26 wherein said synchronous sampling means includes means for generating a synchronized clock signal and a sample and hold circuit means responsive to said synchronized clock signal and to said combined signal for sampling said combined signal.

28. A data transmission system according to claim 27 wherein said synchronized clock signal gEnerator includes means responsive to an external synchronizing signal for generating said synchronized clock signal.

29. A data transmission system according to claim 27 wherein said synchronized clock signal generating means include a band-pass filter means for filtering a predetermined frequency signal from said combined signal, said predetermined frequency corresponding to the synchronous frequency of said data signal;

a controlled oscillator responsive to the output of said band-pass filter for generating a synchronizing signal; and

means responsive to said synchronizing signal for generating said synchronized clock signal.

30. A data transmission system according to claim 26 wherein said data signal generating means includes means for generating said group of digital data signals which include a plurality of signals selectively having an amplitude of a predetermined level 1 and an amplitude at a second predetermined level 0 which is lower than said first predetermined level so as to enhance synchronous sampling at said receiving means.

31. A data transmission system according to claim 28 comprising variable gain amplifier means coupling said combined signal to said synchronous sampling means.

32. A data transmission system according to claim 31 wherein said variable gain amplifier means comprises a logarithmic amplifier.

33. A data transmission system according to claim 26 wherein said synchronous sampling means includes means for generating a synchronized clock signal of a first predetermined frequency, and a means for generating a synchronized clock signal of a second frequency substantially higher than said first frequency;

and means for selectively sampling said combined signal at one of said frequencies.

34. A data transmission system according to claim 33 wherein said synchronous sampling means includes means for sampling said combined signal at said second frequency to detect a peak value of a data bit which is part of said data signal.

35. A data transmission system according to claim 34 wherein said synchronous sampling means includes means responsive to said peak value detecting means for detecting the phase of the peak value of the data bit;

and means for correcting the phase of said synchronized clock signal of said first predetermined frequency as a function of the phase of the peak value of the data bit.

36. A data transmission system according to claim 26 comprising an analog-to-digital converter coupling the output of said sampling means to said arithmetic means.

37. A data transmission system according to claim 26 wherein said means responsive to said sum values for indicating the presence of valid data comprises a digital comparator for comparing a sum value with a predetermined level;

and shift register means coupled to the output of said comparator for storing valid data output from said digital comparator.

38. A method for transmitting data in conjunction with a program source material signal comprising:

repetitively superposing the same synchronous data signal on the program source material signal to form a combined signal, said data signal being synchronous with a given frequency and having an amplitude level within the amplitude range of the ambient noise appearing in said program source material signal;

transmitting said combined signal;

receiving and operating on said combined signal to extract said data signal from said combined signal, said receiving and operating steps comprising;

synchronously amplitude sampling said combined signal in synchronism with the synchronous frequency of said data signal;

adding the amplitude value of a sample corresponding to a given portion of the data signal with the value corresponding to the algebraic sum of the previously sampled amplitude values of said given portion of the data signal, and storing said algebraic sum value of said amplitude values of said samples;

comparing said algebraic sum value with a predetermined value for indicating presence of valid data upon said algebraic sum value reaching said predetermined value; and

generating a representation corresponding to said valid data.

39. A method for receiving and operating on a combined signal which includes a repetitive synchronous data signal unit superposed within the amplitude range of the ambient noise existing in an audio program source material signal and for extracting said data signal from said combined signal, comprising:

synchronously amplitude sampling said combined signal in synchronism with the synchronous frequency of said data signal;

adding the amplitude value of a sample corresponding to a given portion of the data signal with the algebraic sum of the amplitude values of samples corresponding to the previous occurrences of said given portion of said data signal;

storing said algebraic sum value of said amplitude values of said samples;

comparing said algebraic sum value with a predetermined value for indicating the presence of valid data upon said algebraic sum value reaching said predetermined value; and

generating a representation corresponding to said valid data.

40. A data transmission system according to claim 1, wherein said program source material is a television signal, and including means for detecting the presence of video information in said television signal.

41. A data transmission system according to claim 40, wherein said television signal includes a vertical sync signal, and said detecting means includes means responsive to the vertical sync signal of said television signal.

42. Apparatus according to claim 26, wherein said program source material is a television signal, and including means for detecting the presence of video information in said television signal.

43. Apparatus according to claim 42, wherein said television signal includes a vertical sync signal, and said detecting means includes means responsive to the vertical sync signal of said television signal.