Apparatus and method for receiving audio signals transmitted as part of a television video signal

• US 4,665,431 A
• Filed: 08/16/1982
• Issued: 05/12/1987
• Est. Priority Date: 06/24/1982
• Status: Expired due to Term

• Current Assignee: Technology Licensing Corporation
• Original Assignee: J. Carl Cooper
• Inventors: Cooper, J. Carl
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/408,470
• Time in Patent Office: 1,730 Days
• Field of Search: 358/145, 358/142, 358/143, 358/144, 358/197, 358/198, 358/147, 375/27
• US Class Current: 348/480
• CPC Class Codes: H04N 7/084 with signal insertion during the horizontal blanking interval only
• CPC Class Codes: H04N 7/085 the inserted signal being digital
• CPC Class Codes: H04N 7/0881 the signal being time-compressed before its insertion and subsequently decompressed at reception

Abstract

The apparatus and method for receiving one or more audio frequency signals transmitted on a television video signal includes a decoder comprised of a pulse separator to recover modulated pulses from said video signal and a demodulator to demodulate said modulated pulses from said separator to recover said audio signal. Also included is an encoding apparatus and method for encoding modulated pulses responsive to audio signals on a video signal.

Claims

1. Apparatus for recovering a secondary signal which has been previously encoded on a video signal which encoding utilizes a modulated signal responsive to said secondary signal which modulated signal was combined with said video signal without increasing the bandwith required by said video signal or causing substantial amount of synchronizing information to be deleted from said video signal, including in combination separator means responsive to said video signal to determine the points on said video signal from which said modulated signal may be recovered in response to a clocking signal phase locked to said video and demodulator means responsive to said separator means and said modulated signal to recover said secondary signal.

3. Apparatus as claimed in claim 1 or 2 wherein said separator means is responsive to said video signal to provide a clocking signal utilized by said demodulator means which demodulator means contains an analog memory responsive to said clocking signal to output analog samples at a predetermined rate.

4. Apparatus as claimed in claim 1 or 2 wherein said modulated signal is a difference signal derived from present and past portions of said secondary signal.

5. Apparatus as claimed in claim 1 or 2 wherein said modulated signal is a multiple level signal which is constrained in amplitude to three or more distinct levels.

8. Apparatus as claimed in claims 1, 2, 6 or 7 wherein said secondary signal is a television program audio signal said video signal has the same number of synchronizing pulses before and after said combination and said modulated signal is a pulse amplitude modulated signal previously generated in response to said secondary signal which pulse amplitude modulated signal in input to said demodulator means which demodulator means processes said modulated signal effecting recovery of said secondary signal which processing includes removing modulating frequency components from said modulated signal.

2. Apparatus for decoding a secondary signal which has been combined with and transmitted as part of a television video signal including in combination separator means responsive to blanking areas of said video signal which areas include the video portion of the vertical blanking interval of said video signal and further responsive to a sampling signal phase locked to the synchronizing portion of said video signal to determine the points on said video signal from which said combined secondary signal may be recovered and demodulator means responsive to said separator means and said video signal to recover and output an output signal essentially the same as said secondary signal.

6. Apparatus for recovering from a first video signal a secondary signal which was previously used to generate an analog modulated signal which modulated signal was combined with said video signal including in combination separator means to generate a third signal phase locked to the sync pulses of said video signal to determine the location of said modulated signal, storage means responsive to said third signal phase locked to sync pulses of said separator means and said video signal to recover and store said modulated signal from said determined locations in said video signal which storage means outputs said modulated signal at a constant rate and further including low pass filter means operable in response to said storage means to output analog information which is essentially the same as said secondary signal.

7. Apparatus as claimed in claim 6 wherein said storage means samples said modulated signal at predetermined locations in the blanking area of said video signal which samples are stored in said storage means with said low pass filter means responsive to said samples to output said output analog information.

9. Apparatus for decoding a sampled audio frequency signal which is carried in pulse modulated form on a television video signal in the blanking interval thereof which video signal contains synchronizing pulses unaffected in quantity by such carriage including in combination separator means responsive to said video signal to provide clocking pulses locating the position of the sampled audio frequency signal and demodulation means response to said clocking pulses and the television video signal to sample said modulated sampled audio frequency signal at predetermined locations in the blanking interval to recover said pulse modulated signal from the television video signal, which apparatus includes filter means to perform sample frequency filtering of said recovered pulse modulated signal.

10. The method of decoding an audio frequency signal which was previously encoded in the blanking interval of a television video signal which video signal is passed through or stored on standard video equipment, including a step of sampling said encoded audio frequency signal on said video signal at predetermined locations in the blanking interval thereof said locations determined in response to sync pulses of said video signal, a step of temporarily storing said samples in a memory, a step of outputting said samples from said memory at a steady rate and a further step of removing encoding related components from said output samples thus recovering said audio frequency signal.

11. The method of recovering a secondary signal which was previously used to generate a modulated signal which modulated signal is carried on a television video signal without reducing the number of synchronizing pulses of said video signal including a step of generating a first clocking signal responsive to synchronizing information of said video signal and generating a second stable clocking signal, a step of sampling said modulated signal in response to said first clocking signal, a step of storing said samples in a memory, a step of removing said samples from said memory in response to said second clocking signal and a further step of filtering said removed samples to recover said secondary signal.

12. The method as claimed in claim 11 wherein said modulated signal is a difference signal derived from past and present portions secondary signal.

13. The method of restoring a continuous secondary signal which has been compressed in time and combined in analog form with a video signal without substantially reducing the number of synchronizing pulses of said video signal including a step of sampling said video signal to produce an intermittent secondary signal, a step of storing said intermittent secondary signal produced by said sampling, a step of continuously retrieving said stored intermittent secondary signal and a step of converting retrieved signals to a continuous analog signal essentially the same as said continuous secondary signal.

14. The method as claimed in claim 13 wherein said intermittent secondary signal is stored in analog form.

15. The method as claimed in claim 13 wherein said intermittent secondary signal is digitized as part of said sampling step, stored in digitized form in said storage step and converted from digital back to analog as part of said converting step.

16. The method as claimed in claim 13 wherein said continuous secondary signal is a multiple level signal having three or more distinct levels.

17. An apparatus for receiving low bandwidth signals transmitted as part of a television signal having a timing pulse and a section without substantive picture related information, the transmission including converting the low bandwidth signals into an intermittent sped up modulated signal related to the timing pulse and including the modulated signal into the section of the television signal without substantive picture related information to be transmitted therewith, said receiving apparatus comprising meas to separate the sped up intermittent modulated signal from the section of the television signal without substantive picture related information, said separation means utilizing the timing pulse of the television signal, and means to reconvert theseparated sped up intermittent modulated signal back into a signal substantially equivalent to the low bandwidth signal.

18. The apparatus of claim 17 characterized in that the intermittent modulated signal has a frequency related to the television signal.

19. The apparatus of claim 17 wherein the television signal has a horizontal sync rate and characterized in that the intermittent modulated signal utilizes the horizontal sync rate of the television signal as the timing pulse.

20. An apparatus for receiving a low bandwidth signal transmitted as part of a television signal having a timing pulse and a section without substantive picture related information, the television signal including the low bandwidth signal having sampled at one clock rate, and converted into an analog intermittent signal at a different second clock rate, the intermittent signal having substantially the same information as the low bandwidth signal, the second clock rate being related to the timing pulse of the television signal, and combining the intermittent signal into the section of the television signal without substantive picture related information for transmission with the television signal, said receiving apparatus comprising means to receive the television signal including the intermittent signal, uncombining means to separate the intermittent signal from the television signal, said uncombining means having a clock rate substantially equal to the second clock rate, and means to reconvert the intermittent signal back into a signal substantially equivalent to the low bandwidth signal.

21. The apparatus of claim 20 characterized in that said clock rate of said uncombining measn utilizes to the timing pulse of the television signal.

22. The apparatus of claims 20 or 21 wherein the television signal has a horizontal sync timing and characterized in that the second clock rate is responsive to the horizontal sync timing of the television signal.