Telephonic communications – Having light wave or ultrasonic link for speech or paging... – Including fiber optic link within telephone network
Patent
1989-03-13
1990-09-04
Ng, Jin F.
Telephonic communications
Having light wave or ultrasonic link for speech or paging...
Including fiber optic link within telephone network
379103, 358 12, 358 16, 358 85, 358143, H04M 1100, H04N 714
Patent
active
049550489
ABSTRACT:
In a method for multiplexing the transmission of audio and video signals, the video signal is separated into a luminance signal and a chrominance signal. The luminance signal is then modulated, and the chrominance signal is balanced-modulated with a low-frequency carrier. The chrominance signal is then converted to a lower frequency. The audio signal, frequency-modulated luminance signal and frequency-converted chrominance signal and frequency-converted chrominance signal are multiplexed by frequency division to be transmitted across telephone cable. Consequently, in comparison with the conventional transmission method which executes direct frequency modulation of the video signal, the band-width of the frequency-modulated luminance signal becomes narrower to eventually facilitate multichannel transmission. The harmful influence from interference from external radio waves or from metallic members used to fix the cable is removed on the receiver side. Accordingly, satisfactory picture transmission can be performed without the necessity of any additional coaxial cable for video signal transmission.
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Itsumi Tadashi
Iwamura Soichi
Murakami Satoshi
Chan Wing F.
Ng Jin F.
Sharp Kabushiki Kaisha
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