EP0244260A2
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EP
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Method and system for multiplex transmission of an audio signal and a video signal through a communication cable
Assignee: Sharp Corp
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Filing: 1987-04-30
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Granted: —
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Expires: 2007-04-30
Abstract
Abstract In a method for multiplex transmission of audio and video signals according to the present invention, first the video signal is separated into a luminance signal and a chrominance signal, then a luminance carrier is frequency-modulated with the luminance signal while the chrominance signal is down converted to a lower band, and such audio signal, frequency-modulated luminance carrier and down converted chrominance signal are multiplexed by frequency division to be transmitted. Consequently, in comparison with the conventional transmission method which executes direct frequency-modulation of the video signal, the bandwidth necessary for transmission of the frequency-modulated luminance carrier becomes narrowerto eventually facilitate mutt- ichannel transmission. And if any amplitude-modulated component is generated in the carrier components in the multiplex transmission by the harmful influence from interference induced by external radio waves through the cable or from metallic members used to fix the cable, there occurs no deterioration in the picture quality since such component is removed on the receiver side prior to demodulation of the frequency-modulated video carrier. Accordingly, satisfactory picture transmission can be performed without the necessity of any additional co-axial cable for video signal transmission. And it is also possible to utilize an existing interphone cable for transmission of the video carrier. Since no impediment is caused despite any multipath reflection or interference of medium waves, cable installation can be achieved easily regardless of such harmful influence from medium waves or multipath reflection, hence realizing simplified and low-cost transmission of multiplex audio and video-carrier. Furthermore, when installing a door camera in addition to the interphone system used to baseband transmission of audio signal, a desired operation is rendered possible by additionally furnishing the existing interphone equipment with a video carrier transmitter/receiver and the video processors.
Inventors
- 👤 Soichi Iwamura
- 👤 Satoshi Murakami
- 👤 Tadashi Itsumi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 14:34
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/10; H04N7/14; H04N7/141; H04N7/148; H04N7/18; H04N7/183; H04N7/186
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
131 words
A method for audio-video multiplex transmission through a pair of telephone communication cables by multiple x ing a bidirectionally baseband-transmitted audio information and a unidirectionally or bidirectionally transmitted video information, comprising the steps of: on a video cameras transmitter side, separating the video signal into a luminance signal and a chrominance signal, then modulating a luminance carrier with said luminance signal while down converting said chrominance signal to a lower band, subsequently multiplexing said audio signal, said frequency-modulated luminance carrier and said down-converted chrominance signal by frequency division, and transmitting said multiplex signals: and on a video carrier's receiver side, reproducing said luminance signal by frequency-demodulation while restoring said chrominance signal by up-conversion, and combining said reproduced luminance signal and chrominance signal with each other to obtain the original video signal
Claim 2
Independent Claim
131 words
A method for audio-video multiplex transmission through a pair of telephone communication cables by multiple x ing a bidirectionally baseband-transmitted audio information and a unidirectionally or bidirectionally transmitted video information, comprising the steps of: on a video cameras transmitter side, separating the video signal into a luminance signal and a chrominance signal, then modulating a luminance carrier with said luminance signal while down converting said chrominance signal to a lower band, subsequently multiplexing said audio signal, said frequency-modulated luminance carrier and said down-converted chrominance signal by frequency division, and transmitting said multiplex signals: and on a video carrier's receiver side, reproducing said luminance signal by frequency-demodulation while restoring said chrominance signal by up-conversion, and combining said reproduced luminance signal and chrominance signal with each other to obtain the original video signal
Claim 3
Independent Claim
114 words
A method for audio-video multiplex transmission by multiplexing a bidirectionally transmitted audio signal and a unidirectionally or bidirectionally transmitted video carrier, comprising the steps of: on the transmitter side, frequency-modulating a video carrier with said video signal to produce a frequency-modulated carrier with a band ranging 1 to 10 MHz, then multiplexing said frequency-modulated video carrier and said audio signal to be - baseband-transmitted in a range below 10kHz, and transmitting said multiplex signals through a pair or one of pairs of telephone communication cables; and on the receiver side, separating said multiplex signals into the audio signal and the video carrier, and frequency-demodulating said separated video carrier after removing the amplitude-modulated component therefrom.
Claim 4
Independent Claim
114 words
A method for audio-video multiplex transmission by multiplexing a bidirectionally transmitted audio signal and a unidirectionally or bidirectionally transmitted video carrier, comprising the steps of: on the transmitter side, frequency-modulating a video carrier with said video signal to produce a frequency-modulated carrier with a band ranging 1 to 10 MHz, then multiplexing said frequency-modulated video carrier and said audio signal to be - baseband-transmitted in a range below 10kHz, and transmitting said multiplex signals through a pair or one of pairs of telephone communication cables; and on the receiver side, separating said multiplex signals into the audio signal and the video carrier, and frequency-demodulating said separated video carrier after removing the amplitude-modulated component therefrom.
Claim 5
Independent Claim
140 words
A system for audio-video multiplex transmission through a pair of telephone communication cables by multiplexing a bidirectionally baseband-transmitted audio information and a unidirectionally or bidirectionally transmitted video information, comprising on a video carrier's transmitter side, means for separating the video signal into a luminance signal and a chrominance signal, means for modulating a luminance carrier with said luminance signal, means for down converting said chrominance signal to a lower band, means for subsequently multiplexing said audio signal, said frequency-modulated luminance carrier and said down-converted chrominance signal by frequency division, and means for transmitting said multiplex signals: and comprising on a video carrier's receiver side, means for reproducing said luminance signal by frequency-demodulation, means for restoring said chrominance signal by up-conversion, and means for combining said reproduced luminance signal and chrominance signal with each other to obtain the original video signal.
Claim 6
Independent Claim
140 words
A system for audio-video multiplex transmission through a pair of telephone communication cables by multiplexing a bidirectionally baseband-transmitted audio information and a unidirectionally or bidirectionally transmitted video information, comprising on a video carrier's transmitter side, means for separating the video signal into a luminance signal and a chrominance signal, means for modulating a luminance carrier with said luminance signal, means for down converting said chrominance signal to a lower band, means for subsequently multiplexing said audio signal, said frequency-modulated luminance carrier and said down-converted chrominance signal by frequency division, and means for transmitting said multiplex signals: and comprising on a video carrier's receiver side, means for reproducing said luminance signal by frequency-demodulation, means for restoring said chrominance signal by up-conversion, and means for combining said reproduced luminance signal and chrominance signal with each other to obtain the original video signal.
Claim 7
Independent Claim
120 words
A system for audio-video multiplex transmission by multiplexing a bidirectionally transmitted audio signal and a unidirectionally or bidirectionally transmitted video carrier, comprising, on the transmitter side, means for frequency-modulating a video carrier with said video signal to produce a frequency-modulated carrier with a band ranging 1 to 10 MHz, means for multiplexing said frequency-modulated video carrier and said audio signal to be baseband-transmitted in a range below 10kHz, and means for transmitting said multiplex signals through a pair or one of pairs of telephone communication cables; and comprising on the receiver side, means for separating said multiplex signals into the audio signal and the video carrier, and means for frequency-demodulating said separated video carrier after removing the amplitude-modulated component therefrom.
Claim 8
Independent Claim
120 words
A system for audio-video multiplex transmission by multiplexing a bidirectionally transmitted audio signal and a unidirectionally or bidirectionally transmitted video carrier, comprising, on the transmitter side, means for frequency-modulating a video carrier with said video signal to produce a frequency-modulated carrier with a band ranging 1 to 10 MHz, means for multiplexing said frequency-modulated video carrier and said audio signal to be baseband-transmitted in a range below 10kHz, and means for transmitting said multiplex signals through a pair or one of pairs of telephone communication cables; and comprising on the receiver side, means for separating said multiplex signals into the audio signal and the video carrier, and means for frequency-demodulating said separated video carrier after removing the amplitude-modulated component therefrom.
Claim 9
Dependent Claim
80 words
A transmitter for an audio/video multiplex transmission system in which multiplexed audio and video signals are transmitted from the transmitter to a receiver, the transmitter comprising means for separating the video signal into luminance and chrominance signals; means for modulating a luminance carrier with the luminance signal; means for down-converting the chrominance signal; means for multiplexing the audio signal, the modulated luminance carrier and the down-converted chrominance signal by frequency division; and means for outputting the multiplexed signal for transmission.
Claim 10
Dependent Claim
80 words
A transmitter for an audio/video multiplex transmission system in which multiplexed audio and video signals are transmitted from the transmitter to a receiver, the transmitter comprising means for separating the video signal into luminance and chrominance signals; means for modulating a luminance carrier with the luminance signal; means for down-converting the chrominance signal; means for multiplexing the audio signal, the modulated luminance carrier and the down-converted chrominance signal by frequency division; and means for outputting the multiplexed signal for transmission.
Claim 11
Dependent Claim
85 words
A receiver to be used in an audio/video multiplex transmission system for receiving a multiplexed signal produced by a transmitter according to claim 5, the receiver comprising; means for demultiplexing the received signal by frequency division to separate the audio signal, the modulated luminance signal and the down-converted chrominance signal; means for reproducing the luminance signal by frequency demodulation; means for restoring the chrominance signal by up-conversion; and means for combining the reproduced luminance signal and the restored chrominance signal to obtain the video signal.
References Cited (Backward Citations)
No citation records indexed.
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