Video modem for transmitting video data over ordinary telephone wires
First Claim
1. A method for transmitting video information over a single pair of unshielded twisted pair (UTP) wires, comprising the steps of:
- (1) frequency modulating a first carrier signal in accordance with a first composite video signal having a luminance component and a color subcarrier and producing thereby a first FM signal comprising a first upper sideband and a first lower sideband each including said color subcarrier of said first composite video signal;
(2) filtering said first FM signal with a first band pass filter to suppress said first upper sideband and to pass said first lower sideband, and producing thereby a first filtered signal having a frequency bandwidth of approximately 6 MHz; and
(3) from a first physical location, injecting said first filtered signal into said single pair of UTP wires.
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Accused Products
Abstract
An apparatus and method is provided for modulating and transmitting full-motion, television-quality color video signals along with digital data signals over a pair of ordinary unshielded twisted pair telephone wires without interfering with normal telephone data on the wires. The invention is characterized by a transmission method involving frequency modulation of a baseband video signal and subsequent filtering to suppress an upper sideband corresponding to a color component of the original video signal. The filtered signal is received from the telephone wires at a different location, filtered, demodulated and provided to a display device. Full-duplex operation over the same pair of wires is possible, such that two video signals may be simultaneously transmitted, each signal having an approximate bandwidth of 6 MHz and shifted to a desirable non-interfering frequency location within the approximately 20 MHz of usable bandwidth on the telephone wires. No pre-emphasis or de-emphasis is required to achieve good quality video transmission. The system has many applications including video distribution, conferencing, and communications.
225 Citations
55 Claims
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1. A method for transmitting video information over a single pair of unshielded twisted pair (UTP) wires, comprising the steps of:
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(1) frequency modulating a first carrier signal in accordance with a first composite video signal having a luminance component and a color subcarrier and producing thereby a first FM signal comprising a first upper sideband and a first lower sideband each including said color subcarrier of said first composite video signal; (2) filtering said first FM signal with a first band pass filter to suppress said first upper sideband and to pass said first lower sideband, and producing thereby a first filtered signal having a frequency bandwidth of approximately 6 MHz; and (3) from a first physical location, injecting said first filtered signal into said single pair of UTP wires. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 32)
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21. Apparatus for transmitting video information over a single pair of unshielded twisted pair (UTP) wires, comprising:
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first frequency modulation means for frequency modulating a first carrier signal in accordance with a first composite video signal having a luminance component and a color subcarrier and for producing thereby a first FM signal comprising a first upper sideband and a first lower sideband each including said color subcarrier of said first composite video signal; first filtering means, coupled to said first frequency modulation means, for filtering said first FM signal to suppress said first upper sideband and to pass said first lower sideband, and for producing thereby a first filtered signal having a frequency bandwidth of approximately 6 MHz; and first injecting means, coupled to said first filtering means, for injecting said first filtered signal into said single pair of UTP wires at a first physical location. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 33, 34, 35, 36, 37, 38, 39, 40)
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41. A video device comprising:
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an input terminal for accepting a first composite video signal having a first luminance component and a first color subcarrier; a telephone terminal connectable to an unshielded twisted pair telephone line; an FM modulator, coupled to said input terminal, for modulating said first composite video signal onto a carrier signal and producing thereby a first FM signal comprising a first upper sideband and a first lower sideband each including said first color subcarrier; a bandpass filter coupled to said FM modulator and having a passband of approximately 6 MHz which suppresses said first upper sideband and passes said first lower sideband, producing therefrom a first filtered FM signal; and a transformer coupled between said bandpass filter and said telephone terminal for driving said telephone terminal in accordance with said first filtered FM signal. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52)
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53. Apparatus for transmitting video information over a single pair of unshielded twisted pair (UTP) wires, comprising:
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first frequency modulation means for frequency modulating a first carrier signal in accordance with a first composite video signal having a luminance component and a color subcarrier and for producing thereby a first FM signal comprising a first upper sideband and a first lower sideband each including said color subcarrier of said first composite video signal; first filtering means, coupled to said first frequency modulation means, for filtering said first FM signal to suppress said first lower sideband and to pass said first upper sideband, and for producing thereby a first filtered signal having a frequency bandwidth of approximately 6 MHz; and first injecting means, coupled to said first filtering means, for injecting said first filtered signal into said single pair of UTP wires at a first physical location. - View Dependent Claims (54)
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55. A method for transmitting video information over a single pair of unshielded twisted pair (UTP) wires, comprising the steps of:
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(1) using a frequency modulation modulator to frequency modulate a carrier signal using a composite NTSC-compatible video signal comprising a luminance component and a chrominance component as a modulating signal, and producing thereby a frequency modulated carrier signal comprising an upper sideband and a lower sideband each comprising modulated portions of the composite video signal; (2) filtering the frequency modulated carrier signal to suppress the upper sideband and producing thereby a filtered signal having a frequency bandwidth of approximately 6 MHz; and (3) injecting the filtered signal into the single pair of UTP wires.
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Specification