System for combining multiple audio channels into the baseband video signal and the recovery of the audio channels therefrom

• US 5,023,707 A
• Filed: 09/21/1989
• Issued: 06/11/1991
• Est. Priority Date: 12/02/1985
• Status: Expired due to Fees

• Current Assignee: Media Transference International Limited
• Original Assignee: Media Transference International Limited
• Inventors: Briggs, James B.
• Primary Examiner(s): RICHARDSON, ROBERT
• Application Number:
  US07/411,214
• Time in Patent Office: 628 Days
• Field of Search: 369/2, 360/30, 360/19.1, 358/341, 358/343
• US Class Current: 386/204
• CPC Class Codes: H04N 5/9204 using frequency division multiplex

Abstract

A system for enabling a plurality of audio signals respectively representing different languages to be recorded on a present-day video tape in a present day video tape recorder without requiring any additional space on the tape. The bands of audio signals representing the different languages are selectively reproduced so that anyone viewing the video program recorded on the video tape may select any one of a number of languages to accompany the video program. In accordance with the invention, the bands of audio signals representing the different languages are heterodyned to different frequency bands, and are caused to modulate a sub-carrier which, in turn, is inserted into the video signals representing the video content. This enables the audio signals to be recorded in the video tracks of the tape together with the video signals.

Claims

1. A method for encoding a plurality of audio signals, representative of audio in different languages, which correspond to a single video signal, said plurality of audio signals being encoded within the bandwidth of standard format composite video signal prior to the translation of a baseband video signal into a modulated format used for conduction, transmission and recording of a video signal said method comprising the steps of:

allocating the audio signal representative of each language to a separate audio channel;

filtering a predetermined frequency from the baseband video signal to remove energy from the baseband video signal at the predetermined frequency;

modulating a carrier signal by the audio signals from the audio channels, said carrier signal having a frequency equal to the predetermined frequency; and

inserting the modulated carrier signal at the predetermined frequency into the baseband video signal;

whereby the audio signals representative of audio in different languages are encoded into the baseband video signal, thereby avoiding the addition of signals outside the baseband video signal and an increase in bandwidth of the signal, and the baseband video signal encoded with the audio signals can be subsequently conducted, transmitted or recorded using unmodified video transmission or recording equipment.

2. The method as described in claim 1, wherein the step of modulating the carrier signal further comprises the steps of:

modulating intermediate carrier signals by the audio signals of the audio channels, each audio signal modulating a different intermediate carrier signal at a different frequency; and

summing the modulated intermediate carrier signals;

wherein the carrier signal is modulated by the summed modulated intermediate carrier signals.

3. The method as described in claim 2, wherein the intermediate carrier signals are generated at frequencies phase locked to the horizontal synchronizing signal of the composite video signal such that the intermediate carrier signals are at frequencies equal to a multiple of the horizontal synchronizing signal of the composite video signal.

4. The method as described in claim 1, wherein the predetermined frequency is in the luminance portion of the baseband video signal.

5. The method as described in claim 4, wherein the predetermined frequency is at 1.6 MHz.

6. The method as described in claim 1, further comprising a method for decoding the baseband video signal encoded with audio signals, comprising the steps of:

separating the modulated carrier signal at the predetermined frequency from the baseband video signal;

demodulating the modulated carrier signal at the predetermined frequency to retrieve at least one audio signal of an audio channel representative of a specific language.

7. The method as described in claim 3, further comprising a method for decoding the baseband video signal encoded with audio signals, comprising the steps of:

separating the modulated carrier signal at the predetermined frequency from the video signal;

demodulating the modulated carrier signal at the predetermined frequency to retrieve the plurality of modulated intermediate carrier signals;

demodulating at least one of the modulated intermediate carrier signals to retrieve an audio signal of an audio channel representative of a specific language.

8. A method for encoding a plurality of audio signal, representative of audio in different languages, which correspond to a single video signal, said plurality of audio signals being encoded within the bandwidth of standard format composite video signal prior to the translation of a baseband video signal into a modulated format used for conduction, transmission and recording of a video signal, said method comprising the steps of:

allocating each audio signal representative of each language to a separate audio channel;

modulating intermediate carrier signals by the audio signals of the audio channels, each audio signal modulating a different intermediate carrier signal of a different frequency;

summing the modulated intermediate carrier signals;

filtering a predetermined frequency from the baseband video signal to remove energy from the baseband video signal at the predetermined frequency;

modulating a carrier signal by the summed modulated intermediate carrier signals, said carrier signal having a frequency equal to the predetermined frequency;

inserting the modulated carrier signal at the predetermined frequency into the baseband video signal;

whereby the audio signals representative of audio in different languages are encoded into the basebond video signal, thereby avoiding the addition of signals outside the baseband video signal and an increase in bandwidth of the signal, and the baseband video signal encoded with the audio signals can be subsequently conducted transmitted or recorded using unmodified video transmission or recording equipment.

9. The method as described in claim 8, wherein the intermediate carrier signals are generated at frequencies phase locked to the horizontal synchronizing signal of the composite video signal such that the intermediate carrier signals are at frequencies equal to a multiple of the horizontal synchronizing signal of the composite video signal.

10. The method as described in claim 8, wherein the predetermined frequency is in the luminance portion of the baseband video signal.

11. The method as described in claim 9, wherein the predetermined frequency is at 1.6 MHz.

12. The method as described in claim 8, further comprising a method for decoding the baseband video signal encoded with audio signals, comprising the steps of:

separating the modulated carrier signal at the predetermined frequency from the video signal;

demodulating the modulated carrier signal at the predetermined frequency to retrieve the plurality of modulated intermediate carrier signals; and

demodulating at least one of the modulated intermediate carrier signals to retrieve an audio signal of an audio channel representative of a specific language.

13. An apparatus for encoding a pluarlity of audio signals, representative of audio in different languages, which correspond to a single video signal, said plurality of audio signals being encoded within the bandwidth of standard format composite video signal prior to the translation of a baseband video signal into a modulated format used for conduction, transmission or recording of a video signal, said apparatus comprising:

a plurality of audio channels to receive the audio signals, each channel receiving one audio signal representative of the audio in a predetermined language;

a filter to remove energy from the baseband video signal at a predetermined frequency;

a first oscillator to produce a carrier signal having a frequency equal to the predetermined frequency;

a first modulating means to modulate the carrier signal at the predetermined frequency, said carrier signal being modulated by the audio signals of the audio channels; and

means for inserting the modulated carrier signal at the predetermined frequency into the baseband video signal;

whereby the audio signals representative of audio in different languages are encoded into the baseband video signal, thereby avoiding the addition of signals outside the baseband video signal and an increase in bandwidth of the signal, and the baseband video signal encoded with the audio signals can be subsequently conducted, transmitted or recorded using unmodified video transmission or recording equipment.

14. The apparatus as described in claim 13, further comprising:

a plurality of second oscillators which produce a plurality of intermediate carrier signals at different frequencies; and

a second modulating means to modulate the intermediate carrier signals by the audio signals received by the audio channels, each audio signal modulating a different intermediate carrier signal;

whereby the modulated intermediate carrier signals modulate the carrier signal at the predetermined frequency.

15. The apparatus as described in claim 14, wherein the intermediate carrier signals are generated at frequencies phase locked to the horizontal synchronizing signal of the composite video signal such that the intermediate carrier signals are at frequencies equal to a multiple of the horizontal synchronizing signal of the composite video signal.

16. The apparatus as described in claim 15, wherein the predetermined frequency is in the luminance portion of the baseband video signal.

17. The apparatus as described in claim 16, wherein the predetermined frequency is at 1.6 MHz.

18. The apparatus as described in claim 14, wherein the second modulating means is an amplitude modulating means.

19. The apparatus as described in claim 13, wherein the first modulating means is a frequency modulating means.

20. The apparatus as described in claim 13, further comprising a means for decoding the baseband video signal to retrieve the encoded audio signals comprising:

filter means for separating the modulated carrier signal at the predetermined frequency from the baseband video signal; and

a first demodulating means for demodulating the modulated carrier signal at the predetermined frequency to retrieve at least one of the audio signals representative of a specific language.

21. The apparatus as described in claim 14, further comprising a means for decoding the baseband video signal to retrieve the encoded audio signals comprising:

filter means for separating the modulated carrier signal at the predetermined frequency from the baseband video signal; and

a first demodulating means for demodulating the modulated carrier signal at the predetermined frequency to retrieve the plurality of modulated intermediate carrier signals; and

a second demodulating means for demodulating at least one of the modulated intermediate carrier signals to retrieve at least one audio signal of an audio channel representative of a specific language.

22. An apparatus for encoding a plurality of audio signals, representative of audio in different languages, which correspond to a single video signal, said plurality of audio signals being encoded within the bandwidth of a standard format composite video signal prior to the translation of a baseband video signal into a modulated format used for conduction, transmission or recording of a video signal said apparatus comprising:

a plurality of audio channels to receive the audio signals, each channel receiving one audio signal representative of the audio in a predetermined language;

a plurality of first oscillators which produce a plurality of intermediate carrier signals at different frequencies;

a first modulating means to modulate the intermediate carrier signals by the audio signals received by the audio channels, each audio signal modulating a different intermediate carrier signal;

summing means to sum the modulated intermediate carrier signals;

a filter to remove energy from the base band video signal at a predetermined frequency;

a second oscillator which produces a carrier signal at the predetermined frequency;

a second modulating means to modulate the carrier signal at the predetermined frequency, said carrier signal being modulated by the summed modulated intermediate carrier signals;

means for inserting the modulated carrier signal at the predetermined frequency into the baseband video signal;

whereby the audio signals representative of audio in different languages are encoded into the baseband video signal, thereby avoiding the addition of signals outside the baseband video signal and an increase in bandwidth of the signal, and the baseband video signal encoded with the audio signals can be subsequently conducted, transmitted or recorded using unmodified video transmission or recording equipment.

23. The apparatus as described in claim 22, wherein the intermediate carrier signals are generated at frequencies phase locked to the horizontal synchronizing signal of the composite video signal such that the intermediate carrier signals are at frequencies equal to a multiple of the horizontal synchronizing signal of the composite video signal.

24. The apparatus as described in claim 22, wherein the predetermined frequency is in the luminance portion of the baseband video signal.

25. The apparatus as described in claim 24, wherein the predetermined frequency is at 1.6 MHz.

26. The apparatus as described in claim 22, wherein the first modulating modulating means is an amplitue modulating means.

27. The apparatus as described in claim 22, wherein the second modulating means is a frequency modulating means.

28. The apparatus as described in claim 22, further comprising a means for decoding the baseband video signal to retrieve the encoded audio signals comprising:

filter means for separating the modulated carrier signal at the predetermined frequency from the baseband video signal; and

a first demodulating means for demodulating the modulated carrier signal at the predetermined frequency to retrieve the plurality of modulated intermediate carrier signals; and

a second demodulating means for demodulating at least one of the modulated intermediate carrier signals to retrieve at least one audio signal of an audio channel representative a specific language.