Transmission system for TV signals
First Claim
1. A system for simultaneously transmitting and simultaneously receiving a plurality of signals via a common transponder comprising:
- (1) a plurality of transmitting stations, each including;
(a) means for sampling a signal to be transmitted at a predetermined sampling rate to generate a plurality of digital data words, each of said data words being indicative of the magnitude of the sampled signal;
(b) memory means for storing said plurality of digital words;
(c) memory read means for reading said stored digital data words at a rate less than said sampling rate to produce a data stream comprising said digital data words at the output of said memory means;
(d) circuit means responsive to said data stream to produce a compressed signal having a bandwidth less than the bandwidth of the original signal;
(e) transmitting means for producing a respective first carrier modulated by said compressed signal;
(f) a transponder responsive to said respective first carrier to produce a respective second carrier modulated with said compressed signal;
(2) a plurality of receiving stations, each including;
(a) receiving means tuned to said respective second carrier, said receiving means also including demodulating means for recovering said compressed signal from said respective second carrier, said compressed signal being available at the output terminal of said receiving means;
(b) digital sampling means for sampling said compressed signal at a preselected rate to produce a plurality of digital data words;
(c) memory means for storing said plurality of digital data words;
(d) memory read means for reading said stored digital data words at a rate higher than said preselected rate to produce a data stream comprising a plurality of digital words; and
(e) circuit means responsive to said data stream to produce a reconstructed signal having the same bandwidth as said signal to be transmitted.
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Accused Products
Abstract
A system for reducing the bandwidth and simultaneously transmitting a plurality of signals through a common transponder. The system is particularly useful for the transmissions of multiple TV signals via a geostationary satellite. Prior to transmission the bandwidth of each of the signals to be transmitted is reduced by one half by deleting every other line and expanding each of the remaining lines to cover a time interval normally occupied by two lines. After transmission through the satellite, each of lines is recorded at a first rate and read back at a higher rate to reduce the time interval of each line to its original value. Each line is repeated twice to reconstruct a TV signal having the same format at the original signal.
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Citations
9 Claims
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1. A system for simultaneously transmitting and simultaneously receiving a plurality of signals via a common transponder comprising:
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(1) a plurality of transmitting stations, each including; (a) means for sampling a signal to be transmitted at a predetermined sampling rate to generate a plurality of digital data words, each of said data words being indicative of the magnitude of the sampled signal; (b) memory means for storing said plurality of digital words; (c) memory read means for reading said stored digital data words at a rate less than said sampling rate to produce a data stream comprising said digital data words at the output of said memory means; (d) circuit means responsive to said data stream to produce a compressed signal having a bandwidth less than the bandwidth of the original signal; (e) transmitting means for producing a respective first carrier modulated by said compressed signal; (f) a transponder responsive to said respective first carrier to produce a respective second carrier modulated with said compressed signal; (2) a plurality of receiving stations, each including; (a) receiving means tuned to said respective second carrier, said receiving means also including demodulating means for recovering said compressed signal from said respective second carrier, said compressed signal being available at the output terminal of said receiving means; (b) digital sampling means for sampling said compressed signal at a preselected rate to produce a plurality of digital data words; (c) memory means for storing said plurality of digital data words; (d) memory read means for reading said stored digital data words at a rate higher than said preselected rate to produce a data stream comprising a plurality of digital words; and (e) circuit means responsive to said data stream to produce a reconstructed signal having the same bandwidth as said signal to be transmitted.
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2. A system for simultaneously transmitting a plurality of TV signals via a common transponder, comprising:
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(1) a plurality of transmitting stations each including; (a) means for selectively deleting lines of a TV signal to be transmitted and for expanding the remaining lines to cover the time interval of the original signal to produce a compressed TV signal comprising fewer lines then said TV signal to be transmitted; (b) transmitting means responsive to said compressed signal to produce a respective first carrier modulated with said compressed TV signal; (2) transponder means responsive to said respective first carrier to produce a respective second carrier modulated with said compressed signal; (3) a plurality of receiving stations, each including; (a) receiving means tuned to said respective second carrier and demodulation means for recovering said compressed signal from said respective second carrier to produce an output signal comprising said compressed signal; (b) circuit means for processing said compressed signal to produce a reconstructed TV signal having the same number of lines as said signal to be transmitted. - View Dependent Claims (3, 4, 5, 6, 7, 8)
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9. A method for transmitting and receiving a plurality of TV signals, comprising the steps of:
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(a) deleting selected lines of each of said TV signals to be transmitted; (b) expanding the remaining lines of each of said TV signals to produce a plurality compressed signals with the time interval of each line of said compressed signal being equal to the time interval by a plurality of lines of said TV signal; (c) modulating a plurality of carriers with said compressed signals to produce a plurality of modulated carriers; (d) simultaneously transmitting said plurality of modulated carriers to a plurality of receivers via a common transponder to a plurality of receiving stations to which each of said modulated carriers are demodulated to recover said plurality of compressed signals; (e) processing each of said plurality of compressed signals to produce a reconstructed TV image by storing lines of said compressed signal in real time, reading said stored compressed signal at a higher rate to produce a reconstructed line having a duration less than the time interval by a line of said compressed signal and repeating said reconstructed line, as necessary, to produce a reconstructed TV signal having a standard format.
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Specification