Telecommunication system for transmitting full motion video
First Claim
1. A telecommunication circuit for transmitting video signals comprising:
- video signal initiation means for providing a broadband video signal of at least 4.5 megahertz band width, line driver means coupled to said video signal initiation means to amplify said broadband video signal and transmit it intact, a link formed of a twisted pair of unloaded telephone wires having opposite ends one of which is coupled to receive said amplified broadband video signal, symmetrical video transformer means coupled to the other of said ends of said twisted pair link to receive and amplify said broadband video signal, correcting amplifier means coupled to receive said broadband video signal from said symmetrical video transformer and to impress thereon an impedance proportional to the impedance in said twisted pair link and in vector opposition thereto to thereby correct said broadband video signal for impedance degradation in said twisted pair link and a video receiver coupled to said correcting amplifier means for receiving said corrected broadband video signal.
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0 Petitions
Accused Products
Abstract
An improved telecommunication system is provided which allows the transmission of full motion color video, voice and data over a communications link formed of a twisted pair of wires of the type currently utilized only for voice and data communications. The signal is transmitted over the twisted pair link as a broadband signal up to a distance of six thousand feet. The twisted pair link exhibits a known impedance to the signal, depending upon the lengths of the twisted pairs of wires in the link. As the signal is received from the twisted pair link it is amplified and an impedance proportional to the impedance of the twisted pair link and vectorially opposite thereto is impressed thereon. A unity gain is achieved whereby the signal degrading effects of the impedance of the twisted pair link are reversed. This results in the accurate reproduction of a video signal over a link including significant lengths of conventional twisted pairs of telephone wires. Moreover, because the compensation for telephone line twisted pair impedance allows the accurate reproduction of a broadband signal, a plurality of different video, telephone and data signals can be multiplexed together and transmitted simultaneously over the same twisted pair link.
225 Citations
19 Claims
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1. A telecommunication circuit for transmitting video signals comprising:
video signal initiation means for providing a broadband video signal of at least 4.5 megahertz band width, line driver means coupled to said video signal initiation means to amplify said broadband video signal and transmit it intact, a link formed of a twisted pair of unloaded telephone wires having opposite ends one of which is coupled to receive said amplified broadband video signal, symmetrical video transformer means coupled to the other of said ends of said twisted pair link to receive and amplify said broadband video signal, correcting amplifier means coupled to receive said broadband video signal from said symmetrical video transformer and to impress thereon an impedance proportional to the impedance in said twisted pair link and in vector opposition thereto to thereby correct said broadband video signal for impedance degradation in said twisted pair link and a video receiver coupled to said correcting amplifier means for receiving said corrected broadband video signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A telecommunication system comprising:
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(a) a video signal source providing a broadband video signal having a frequency band width of at least 4.5 megahertz, (b) line driver means coupled to said video signal source to produce an amplified broadband video signal; (c) a link comprised of an unloaded twisted pair of telephone wires having a known impedance and coupled to receive said amplified broadband video signal intact from said line driver means, (d) a symmetrical video transformer coupled to said twisted pair of telephone wires to receive and amplify said broadband video signal therefrom, (e) correcting amplifier means coupled to said symmetrical video transformer to impress thereon an offsetting impedance to said broadband video signal emanating from said twisted pair link which is proportional and in opposition to said known impedance of said twisted pair link to thereby negate the effects of said known impedance on said broadband video signal from said video source, and (f) a video receiver coupled to receive said broadband video signal from said correcting amplifier means to extract a video image therefrom. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. In a telecommunication circuit including a twisted pair link comprised of an unloaded twisted pair of wires of a known length and having first and second ends, the improvement comprising:
video signal provision means for providing a broadband video signal having a band width of at least 4.5 megahertz, line driver means interposed between said video signal provision means and said first end of said twisted pair link to amplify said broadband video signal intact and to impress a known impedance thereon, whereby said twisted pair link exhibits said known impedance, unity gain amplification means coupled to said second end of said twisted pair link to reproduce said broadband video signal intact with a compensating impedance proportional and opposite to said known impedance impressed thereon, and a video receiver coupled to receive said broadband video signal with said compensating impedance impressed thereon. - View Dependent Claims (19)
Specification