US3752908A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Catv audio interaction system
Assignee: KMS Industries Inc
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Filing: 1972-06-28
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Granted: 1973-08-14
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Expires: 1992-06-28
Abstract
Abstract A central station including a computer is connected via a multichannel CATV cable to a plurality of remote terminal stations. Some of the channels are reserved for commercial television programs. However, a predetermined number of forward television channels are reserved for private television programs which may be generated either at the central station and transmitted on these forward channels to selected terminal stations under the control of the computer, or else a private TV program may be originated at one of the remote terminals, transmitted via the cable on a return television channel thereof to the central station, and then retransmitted from the central station via the cable on a forward television channel thereof to selected remote terminal stations under the control of the computer. Each terminal station contains an audio input means, such as a microphone and an audio transmitter, for permitting a return audio or speech signal to be inserted at the central station upon the audio subcarrier of television signal which is being received by the other remote terminal stations. For a given television channel, all terminal stations use the same audio return channel, thereby communicating in a party line mode. In one embodiment, the return audio carriers for the private television channels are generated at each terminal station and the audio interaction is provided by a novel audio insertion unit using a phase locked loop which does not require demodulation and remodulation of the video signal. In another embodiment of the invention, the audio carriers for the return audio channels are generated at the central station and transmitted to the terminals for modulation by the respective return audio inputs.
Inventors
- 👤 C Boenke
- 👤 R Reimink
- 👤 J Jackson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 07:40
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/14; H04N7/141; H04N7/147
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
417 words
In an audio interactive two-way television cable transmission system wherein a central station and a plurality of remote terminal stations are interconnected by a multi-TV channel transmission line; said central station including television signal transmitter means for transmitting on a forward TV channel a television program signal, including a video signal and a program audio signal, for reception by a remote terminal station; return audio signal input means in said remote station for transmitting a return audio signal modulated on a return audio carrier from said remote terminal station via said return audio channel to said central station; an audio receiver in said central station for receiving the modulated audio carrier and demodulating it to reproduce the return audio signal; and audio insertion means at said central station for superimposing the demodulated return audio signal on the program audio subcarrier of the television signal; an improved audio insertion means comprising: a. first filter means for deriving from said video signal the program audio signal-modulated subcarrier frequency thereof; b. a frequency modulator having a center frequency equal to said subcarrier frequency; c. audio input means for frequency modulating said modulator with the demodulated return audio signal; d. a phase locked loop connected between the output and input of said modulator for phase locking the modulator output to the derived program audio signal-modulated subcarrier frequency; 1) said phase locked loop comprising: a. a phase detector having a first input coupled to the output of said modulator, b. wide pass filter means for passing a phase error signal frequency and also program audio and return audio signal frequencies, and c. first mixer means having one input connected to the output of said phase detector and its output connected to the input of said modulator; e. means for applying the derived program audio signalmodulated subcarrier to a second input of said phase detector in said phase locked loop; f. means for applying the demodulated return audio signal to another input of said first mixer in said phase locked loop, whereby the output of said modulator is said audio subcarrier frequency modulated by both said program and return audio signals; g. second filter means for removing from said television signal its audio subcarrier frequency to produce a video modulated signal; and h. a second mixer means for mixing together said video modulated signal and the output of said modulator to reproduce said television signal having modulated on the audio subcarrier thereof both the original Program audio signal and the return audio signal.
Claim 2
Dependent Claim
417 words
In an audio interactive two-way television cable transmission system wherein a central station and a plurality of remote terminal stations are interconnected by a multi-TV channel transmission line; said central station including television signal transmitter means for transmitting on a forward TV channel a television program signal, including a video signal and a program audio signal, for reception by a remote terminal station; return audio signal input means in said remote station for transmitting a return audio signal modulated on a return audio carrier from said remote terminal station via said return audio channel to said central station; an audio receiver in said central station for receiving the modulated audio carrier and demodulating it to reproduce the return audio signal; and audio insertion means at said central station for superimposing the demodulated return audio signal on the program audio subcarrier of the television signal; an improved audio insertion means comprising: a. first filter means for deriving from said video signal the program audio signal-modulated subcarrier frequency thereof; b. a frequency modulator having a center frequency equal to said subcarrier frequency; c. audio input means for frequency modulating said modulator with the demodulated return audio signal; d. a phase locked loop connected between the output and input of said modulator for phase locking the modulator output to the derived program audio signal-modulated subcarrier frequency; 1) said phase locked loop comprising: a. a phase detector having a first input coupled to the output of said modulator, b. wide pass filter means for passing a phase error signal frequency and also program audio and return audio signal frequencies, and c. first mixer means having one input connected to the output of said phase detector and its output connected to the input of said modulator; e. means for applying the derived program audio signalmodulated subcarrier to a second input of said phase detector in said phase locked loop; f. means for applying the demodulated return audio signal to another input of said first mixer in said phase locked loop, whereby the output of said modulator is said audio subcarrier frequency modulated by both said program and return audio signals; g. second filter means for removing from said television signal its audio subcarrier frequency to produce a video modulated signal; and h. a second mixer means for mixing together said video modulated signal and the output of said modulator to reproduce said television signal having modulated on the audio subcarrier thereof both the original Program audio signal and the return audio signal.
Claim 3
Dependent Claim
36 words
An audio interactive two-way television cable transmission system as defined in claim 1 further comprising a plurality of oscillators for generating a corresponding plurality of return audio carriers, each associated with a different forward TV channel.
Claim 4
Dependent Claim
18 words
second divider means for converting the output of said voltage controlled oscillator to approximately said superaudio carrier frequency;
Claim 5
Dependent Claim
18 words
second divider means for converting the output of said voltage controlled oscillator to approximately said superaudio carrier frequency;
Claim 6
Dependent Claim
41 words
phase detector means connected between said second divider means and said detector and filter means to produce an output error signal dependent upon the difference in phase between the recovered superaudio signal and the output of said voltage controlled oscillator; and
Claim 7
Dependent Claim
41 words
phase detector means connected between said second divider means and said detector and filter means to produce an output error signal dependent upon the difference in phase between the recovered superaudio signal and the output of said voltage controlled oscillator; and
Claim 8
Dependent Claim
43 words
An audio interactive two-way television cable transmission system as defined in claim 2 wherein said oscillators are located in said central station, and means for transmitting the audio carriers to the remote terminal stations to be modulated by the respective return audio signals.
Claim 9
Dependent Claim
95 words
An audio interactive two-way cable television system as defined in claim 3 further comprising a. first divider means at said central station for converting the audio carrier output of each oscillator to a superaudio frequency signal which is applied to said audio insertion means and superimposed on said television signal; b. detector and filter means at said remote terminal for recovering said superaudio signal from said television signal; and c. a phase locked loop at said remote terminal and coupled between said return audio input means and said detector and filter means; said loop comprising:
Claim 10
Dependent Claim
71 words
a narrow band filter connected between input of said voltage controlled oscillator and the output of said phase detector means for locking the voltage controlled oscillator output to the frequency and phase of said audio carrier, whereby the output of said voltage controlled oscillator is modulated in said return audio signal input means by said return audio and transmitted via said return audio channel of said cable to said central station.
Claim 11
Dependent Claim
71 words
a narrow band filter connected between input of said voltage controlled oscillator and the output of said phase detector means for locking the voltage controlled oscillator output to the frequency and phase of said audio carrier, whereby the output of said voltage controlled oscillator is modulated in said return audio signal input means by said return audio and transmitted via said return audio channel of said cable to said central station.
Claim 12
Dependent Claim
25 words
An audio interactive two-way television cable transmission system as defined in claim 2 wherein said plurality of oscillators are located at each remote terminal station.
Claim 13
Dependent Claim
21 words
An audio interactive two-way television cable transmission system as defined in claim 1 wherein said modulator comprises a voltage controlled oscillator.
Claim 14
Dependent Claim
324 words
In an audio interactive two-way television cable transmission system wherein a central station and a pluralty of remote terminal stations are interconnected by a multi-TV channel transmission line; said central station including television signal transmitter means for transmitting on a forward TV channel a television program signal, including a video signal and a program audio signal, for reception by a remote terminal station; return audio signal input means in said remote station for transmitting a return audio signal modulated on a return audio carrier from said remote terminal station via said return audio channel to said central station; an audio receiver in said central station for receiving the modulated audio carrier and demodulating it to reproduce the return audio signal; and audio insertion means at said central station for superimposing the demodulated return audio signal on the program audio subcarrier of the television signal; an improved audio insertion means comprising: a. first filter means for deriving from said television signal the video-audio frequency modulated intercarrier frequency thereof; b. demodulator means for demodulating the intercarrier to produce said program audio signal; c. first mixer means for mixing together the demodulated program audio signal and said return audio signal to produce a composite audio signal; d. second filter means for removing the program audio signal-modulated subcarrier from said television signal to produce a video-signal modulated television carrier; e. circuit means for removing the video signal from said modulated television carrier to produce a pure television carrier; f. modulator means for frequency modulating said composite audio signal at said intercarrier frequency, g. second mixer means for mixing together said pure television carrier and the modulated intercarrier frequency to produce an output of the television audio subcarrier modulated by said composite audio signal, and h. third mixer means for mixing together said video signal-modulated television carrier and the output of said modulator to reproduce said television signal having said composite audio signal modulated on the audio subcarrier thereof.
Claim 15
Dependent Claim
324 words
In an audio interactive two-way television cable transmission system wherein a central station and a pluralty of remote terminal stations are interconnected by a multi-TV channel transmission line; said central station including television signal transmitter means for transmitting on a forward TV channel a television program signal, including a video signal and a program audio signal, for reception by a remote terminal station; return audio signal input means in said remote station for transmitting a return audio signal modulated on a return audio carrier from said remote terminal station via said return audio channel to said central station; an audio receiver in said central station for receiving the modulated audio carrier and demodulating it to reproduce the return audio signal; and audio insertion means at said central station for superimposing the demodulated return audio signal on the program audio subcarrier of the television signal; an improved audio insertion means comprising: a. first filter means for deriving from said television signal the video-audio frequency modulated intercarrier frequency thereof; b. demodulator means for demodulating the intercarrier to produce said program audio signal; c. first mixer means for mixing together the demodulated program audio signal and said return audio signal to produce a composite audio signal; d. second filter means for removing the program audio signal-modulated subcarrier from said television signal to produce a video-signal modulated television carrier; e. circuit means for removing the video signal from said modulated television carrier to produce a pure television carrier; f. modulator means for frequency modulating said composite audio signal at said intercarrier frequency, g. second mixer means for mixing together said pure television carrier and the modulated intercarrier frequency to produce an output of the television audio subcarrier modulated by said composite audio signal, and h. third mixer means for mixing together said video signal-modulated television carrier and the output of said modulator to reproduce said television signal having said composite audio signal modulated on the audio subcarrier thereof.
Claim 16
Dependent Claim
32 words
An audio interactive two-way television cable transmission system as defined in claim 7 wherein said circuit means comprises an amplitude limiter for removing the amplitude modulated video signal from said television carrier.
Claim 17
Dependent Claim
37 words
An audio interactive two-way television cable transmission system as defined in claim 7 wherein said circuit means comprises a phase locked loop operating at the television carrier frequency for removing the video signal from said television carrier.
References Cited (Backward Citations)
US3668307A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-08-13 | 1977-02-12 | 1977-08-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-13 | 1981-02-12 | 1981-08-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-13 | 1985-02-12 | 1985-08-14 | $7700.00 | Window Closed / Lapsed |