Compatible transmission of an encoded signal with a television

• US 4,237,486 A
• Filed: 11/09/1978
• Issued: 12/02/1980
• Est. Priority Date: 11/09/1978
• Status: Expired due to Term

• Current Assignee: ComSonics, Inc.
• Original Assignee: ComSonics, Inc.
• Inventors: Shimp, Richard L.
• Primary Examiner(s): Murray, Richard
• Application Number:
  US05/959,277
• Time in Patent Office: 754 Days
• Field of Search: 358/142, 358/141, 375/42, 375/60, 455/61, 455/91, 370/19, 370/11, 370/6
• US Class Current: 348/475
• CPC Class Codes: H04N 7/081 the additional information signals being transmitted by means of a subcarrier

Abstract

A method and apparatus of compatibly and simultaneously transmitting and receiving an encoded signal with the normal visual and aural carrier of a television signal is disclosed. The encoded signal is used as a modulating signal to frequency modulate the visual carrier frequency signal prior to amplitude modulating the visual carrier frequency signal with a source of composite video signals. Normally, the introduction of additional sideband power even in the form of constant amplitude components will cause visual distortion to a received picture due to the normal Nyquist shaped bandpass characteristics of the intermediate frequency amplifier in the television receiver. This distortion is reduced or eliminated in several ways. The maximum allowable frequency modulation deviation can be limited so that the visual distortion is substantially reduced. Where greater frequency modulation deviation is required, the interfering beats which appear as horizontal lines are made less visable by adjusting the frequency modulation deviation so that these lines roll vertically at a maximum rate. A more desirable approach is to amplitude predistort the frequency modulated visual carrier frequency signal in a complimentary mode to the slope of the video intermediate frequency amplifier circuits of the television receiver. In this manner, an incidental amplitude modulation would be added to the television visual carrier at the transmitter, and this incidental amplitude modulation is in the opposite polarity of the slope of the modulation taking place in the receiver. In other words, by predistorting the frequency modulated visual carrier frequency signal, the signal is in effect pre-equalized to the Nyquist bandpass characteristics of the television receiver intermediate frequency amplifier. The predistortion of the frequency modulated visual carrier signal may be accomplished passively with a bandpass filter having its lower frequency slope at the television picture carrier frequency and having bandpass response characteristics which are complimentary to the Nyquist bandpass characteristics of the television receiver intermediate frequency amplifier. Instead of a passive bandpass filter, similar results are obtained by active, pre-equalizing circuits in the transmitter. Specifically, a phase opposite correction signal derived from the encoded signal is added to the composite video signal prior to amplitude modulating the frequency modulated visual carrier frequency signal. In any case, normal aural carrier generation methods avoid any interference by the addition of a frequency deviation of the visual carrier. The received signal is detected to separately reproduce the encoded signal.

Claims

1. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals, and

transmitting the frequency and amplitude modulated visual carrier frequency signal.

2. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals, and

transmitting the frequency and amplitude modulated visual carrier frequency signal.

3. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating with the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

amplitude predistorting the frequency modulated visual carrier frequency signal in a complimentary mode to the slope of the video intermediate frequency circuit of a television receiver,

amplitude modulating the frequency modulated and predistorted visual carrier frequency signal with a source of composite video signals, and

transmitting the frequency and amplitude modulated visual carrier frequency signals.

4. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprision the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals,

adding a phase opposite correction signal to the composite video signals prior to amplitude modulating the frequency modulated visual carrier frequency signal such that amplitude variations which would occur in a television receiver due to the response characteristics of the receiver are pre-equalized, and

transmitting the frequency and amplitude modulated visual carrier frequency signal.

5. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

phase shifting and adding the encoded signal to a composite video signal to produce a pre-equalized signal,

amplitude modulating the frequency modulated visual carrier frequency signal with the pre-equalized signal, and

transmitting the frequency and amplitude modulated visual carrier frequency signal.

6. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

amplitude modulating in an amplitude modulator the frequency modulated visual carrier frequency signal with a source of composite video signals,

applying a variable bias signal to the amplitude modulator, said variable bias signal being derived from the source of encoded signal with a leading phase shift, and

transmitting the frequency and amplitude modulated visual carrier frequency signal.

7. The method of transmitting recited in claim 6 further comprising the step of adjusting the phase shift of the variable bias signal to eliminate interference in a demodulated composite video signal in a television receiver.

8. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

amplitude predistorting the frequency modulated visual carrier frequency signal in a complimentary mode to the slope of the video intermediate frequency circuit of a television receiver,

amplitude modulating the frequency modulated and predistorted visual carrier frequency signal with a source of composite video signals, and

transmitting the frequency and amplitude modulated visual carrier frequency signals.

9. A method of compatibly and simtultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals,

adding a phase opposite correction signal to the composite video signals prior to amplitude modulating the frequency modulated visual carrier frequency signal such that amplitude variations which would occur in a television receiver due to the response characteristics of the receiver are preequalized, and

transmitting the frequency and amplitude modulated visual carrier frequency signal.

10. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

phase shifting and adding said selected audio tones to a composite video signal to produce a pre-equalized signal,

amplitude modulating the frequency modulated visual carrier frequency signal with the pre-equalized signal, and

transmitting the frequency and amplitude modulated visual carrier frequency signal.

11. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

amplitude modulating in an amplitude modulator the frequency modulated visual carrier frequency signal with a source of composite video signals,

applying a variable bias signal to the amplitude modulator, said variable bias signal being derived from the source of encoded signal with a leading phase shift, and

transmitting the frequency and amplitude modulated visual carrier frequency signal.

12. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals,

generating an aural carrier frequency signal,

frequency modulating the aural carrier frequency signal with an audio signal,

mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

13. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals,

generating an aural carrier frequency signal,

frequency modulating the aural carrier frequency signal with an audio signal,

mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

14. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

amplitude predistorting the frequency modulated visual carrier frequency signal in a complimentary mode to the slope of the video intermediate frequency circuits of a television receiver,

amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals,

generating an aural carrier frequency signal,

frequency modulating the aural carrier frequency signal with an audio signal,

mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

15. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals,

adding a phase opposite correction signal to the composite video signals prior to amplitude modulating the frequency modulated visual carrier frequency signal such that amplitude variations which would occur in a television receiver due to the response characteristics of the receiver are pre-equalized,

generating an aural carrier frequency signal,

frequency modulating the aural carrier frequency signal with an audio signal,

mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

16. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

phase shifting and adding the encoded signal to a composite video signal to produce a pre-equalized signal,

amplitude modulating the frequency modulated visual carrier frequency signal with the pre-equalized signal,

generating an aural carrier frequency signal,

frequency modulating the aural carrier frequency signal with an audio signal,

mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

17. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

amplitude modulating in an amplitude modulator the frequency modulated visual carrier frequency signal with a source of composite video signals,

applying a variable bias signal to the amplitude modulator, said variable bias signal being derived from said selected audio tones with a leading phase shift,

generating an aural carrier frequency signal,

frequency modulating the aural carrier frequency signal with an audio signal,

mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

18. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

amplitude predistorting the frequency modulated visual carrier frequency signal in a complimentary mode to the slope of the video intermediate frequency circuits of a television receiver, amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals,

generating an aural carrier frequency signal,

frequency modulating the aural carrier frequency signal with a audio signal,

mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

19. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier signal of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals,

adding a phase opposite correction signal to the composite video signals prior to amplitude modulating the frequency modulated visual carrier frequency signal such that amplitude variations which would occur in a television receiver due to the response characteristics of the receiver are preequalized,

generating an aural carrier frequency signal,

frequency modulating the aural carrier frequency signal with an audio signal,

mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

20. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising the steps of

generating a visual carrier requency signal,

frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

phase shifting and adding said selected audio tones to a composite video signal to produce a pre-equalized signal,

amplitude modulating the frequency modulated visual carrier frequency signal with the pre-equalized signal,

generating an aural carrier frequency signal,

frequency modulating the aural carrier frequency signal with an audio signal,

mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to a produce a resultant frequency modulated aural carrier frequency signal, and

combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

21. A method of compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

amplitude modulating in an amplitude modulator the frequency modulated visual carrier frequency signal with a source of composite video signals,

applying a variable bias signal to the amplitude modulator, said variable bias signal being derived from said selected audio tones with a leading phase shift,

generating an aural carrier frequency signal,

frequency modulating the aural carrier frequency signal with an audio signal,

mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

22. A method of compatibly and simultaneously transmitting and receiving an encoded signal with the normal visual carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals such that the frequency and amplitude modulated visual carrier frequency signal is pre-equalized to compensate for amplitude variation which would occur in a television receiver due to the response characteristics of the receiver,

transmitting the frequency and amplitude modulated visual carrier frequency signal,

receiving the transmitted signal, and

detecting the narrow band frequency modulation of said visual carrier frequency signal to reproduce the encoded signal.

24. The method of transmitting and receiving as recited in claims 22 or 23, further comprising the step of aurally reproducing the detected encoded signal.

25. The method of transmitting and receiving as recited in claims 22 or 23 further comprising the step of decoding the detected encoded signal.

26. The method of transmitting and receiving as recited in claims 22 or 23, further comprising tbe step of displaying the detected encoded signal.

27. The method of transmitting and receiving as recited in claims 22 or 23, further comprising the step of recording the detected encoded signal.

28. The method of transmitting and receiving as recited in claims 22 or 23, further comprising the steps of

decoding the detected encoded signal, and

displaying the decoded signal.

29. The method of transmitting and receiving recited in claims 22 or 23, further comprising the steps of

decoding the detected encoded signal, and

recording the decoded signal.

23. A method of compatibly and simultaneously transmitting and receiving an encoded signal with the normal visual carrier of a television signal comprising the steps of

generating a visual carrier frequency signal,

frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals such that the frequency and amplitude modulated visual carrier frequency signal is pre-equalized to compensate for amplitude variation which would occur in a television receiver due to the response characteristics of the receiver,

transmitting the frequency and amplitude modulated visual carrier frequency signal,

receiving the transmitted signal, and

detecting the frequency modulation of said visual carrier frequency signal to reproduce the encoded signal.

30. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

means for amplitude modulating the frequency modulated video signals, and

means for transmitting the frequency and amplitude modulated visual carrier frequency signal.

31. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

means for amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals, and

means for transmitting the frequency and amplitude modulated visual carrier frequency signal.

32. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

means for amplitude predistorting the frequency modulated visual carrier frequency signal in a complimentary mode to the slope of the video intermediate frequency circuit of a television receiver,

means for amplitude modulating the frequency modulated and predistorted visual carrier frequency signal with a source of composite video signals, and

means for transmitting the frequency and amplitude modulated visual carrier frequency signals.

33. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

means for amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals,

means for adding a phase opposite correction signal to the composite video signals prior to amplitude modulating the frequency modulated visual carrier frequency signal such that amplitude variations which would occur in a television receiver due to the response characteristics of the receiver are pre-equalized, and

means for transmitting the frequency and amplitude modulated visual carrier frequency signal.

34. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

means for phase shifting and adding the encoded signal to a composite video signal to produce a pre-equalized signal,

means for amplitude modulating the frequency modulated visual carrier frequency signal with the pre-equalized signal, and

means for transmitting the frequency and amplitude modulated visual carrier frequency signal.

35. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

means for amplitude modulating in an amplitude modulator the frequency modulated visual carrier frequency signal with a source of composite video signals,

means for applying a variable bias signal to the amplitude modulator, said variable bias signal being derived from the source of encoded signal with a leading phase shift, and

means for transmitting the frequency and amplitude modulated visual carrier frequency signal.

36. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies with are substantially different than multiples of the television vertical sweep frequency,

means for amplitude predistorting the frequency modulated visual carrier frequency signal in a complimentary mode to the slope of the video intermediate frequency circuit of a television receiver,

means for amplitude modulating the frequency modulated and predistorted visual carrier frequency signal with a source of composite video signals, and

means for transmitting the frequency and amplitude modulated visual carrier frequency signals.

37. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

means for amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals,

means for adding a phase opposite correction signal to the composite video signals prior to amplitude modulating the frequency modulated visual carrier frequency signal such that amplitude variations which would occur in a television receiver due to the response characteristics of the receiver are pre-equalized, and

means for transmitting the frequency and amplitude modulated visual carrier frequency signal.

38. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

means for phase shifting and adding said selected audio tones to a composite video signal to produce a pre-equalized signal,

means for amplitude modulating the frequency modulated visual carrier frequency signal with the pre-equalized signal, and

means for transmitting the frequency and amplitude modulated visual carrier frequency signal.

39. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

means for amplitude modulating an amplitude modulator the frequency modulated visual carrier frequency signal with a source of composite video signals,

means for applying a variable bias signal to the amplitude modulator, said variable bias signal being derived from the source of encoded signal with a leading phase shift, and

means for transmitting the frequency and amplitude modulated visual carrier frequency signal.

40. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

means for amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals,

means for generating an aural carrier frequency signal,

means for frequency modulating the aural carrier frequency signal with an audio signal,

means for mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

means for combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

41. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

means for amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals,

means for generating an aural carrier frequency signal,

means for frequency modulating the aural carrier frequency signal with an audio signal,

means for mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

means for combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

42. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

means for amplitude predistorting the frequency modulated visual carrier frequency signal in a complimentary mode to the slope of the video intermediate frequency circuits of a television receiver,

means for amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals,

means for generating an aural carrier frequency signal,

means for frequency modulating the aural carrier frequency signal with an audio signal,

means for mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

means for combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

43. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

means for amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals,

means for adding a phase opposite correction signal to the composite video signals prior to amplitude modulating the frequency modulated visual carrier frequency signal such that amplitude variations which would occur in a television receiver due to the response characteristics of the receiver are pre-equalized,

means for generating an aural carrier frequency signal,

means for frequency modulating the aural carrier frequency signal with an audio signal,

means for mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

means for combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

44. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

means for phase shifting and adding the encoded signal to a composite video signal to produce a pre-equalized signal,

means for amplitude modulating the frequency modulated visual carrier frequency signal with the pre-equalized signal,

means for generating an aural carrier frequency signal,

means for frequency modulating the aural carrier frequency signal with an audio signal,

means for mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

means for combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

45. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal over a narrow bandwidth with a source of encoded signal,

means for amplitude modulating in an amplitude modulator the frequency modulated visual carrier frequency signal with a source of composite video signals,

means for applying a variable biase signal to the amplitude modulator, said variable bias signal being derived from the source of encoded signal with the leading phase shift,

means for generating an aural carrier frequency signal,

means for frequency modulating the aural carrier frequency signal with an audio signal,

means for mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

means for combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

46. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiplies of the television vertical sweep frequency,

means for amplitude predistorting the frequency modulated visual carrier frequency signal in a complimentary mode to the slope of the video intermediate frequency circuits of a television receiver, amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals,

means for generating an aural carrier frequency signal,

means for frequency modulating the aural carrier frequency signal with an audio signal,

means for mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

means for combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

47. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

means for amplitude modulating the frequency modulated visual carrier frequency signal with a source of composite video signals,

means for adding a phase opposite correction signal to the composite video signals prior to amplitude modulating the frequency modulated visual carrier frequency signal such that amplitude variations which would occur in a television receiver due to the response characteristics of the receiver are pre-equalized,

means for generating an aural carrier frequency signal,

means for frequency modulating the aural carrier frequency signal with an audio signal,

means for mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

means for combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

48. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

means for phase shifting and adding said selected audio tones to a composite video signal to produce a pre-equalized signal,

means for amplitude modulating the frequency modulated visual carrier frequency signal with the pre-equalized signal,

means for generating an aural carrier frequency signal,

means for frequency modulating the aural carrier frequency signal with an audio signal,

means for mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

means for combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.

49. A transmitter for compatibly and simultaneously transmitting an encoded signal with the normal visual and aural carrier of a television signal comprising:

means for generating a visual carrier frequency signal,

means for frequency modulating the visual carrier frequency signal with audio tones selected according to a source of encoded signal, said audio tones having frequencies which are substantially different than multiples of the television vertical sweep frequency,

means for amplitude modulating in an amplitude modulator the frequency modulated visual carrier frequency signal with a source of composite video signals,

means for applying a variable bias signal to the amplitude modulator, said variable bias signal being derived from said selected audio tones with a leading phase shift,

means for generating an aural carrier frequency signal,

means for frequency modulating the aural carrier frequency signal with an audio signal,

means for mixing the frequency modulated visual carrier frequency and aural carrier frequency signals to produce a resultant frequency modulated aural carrier frequency signal, and

means for combining and transmitting the frequency and amplitude modulated visual carrier frequency signal and the resultant frequency modulated aural carrier frequency signal.