Video modem for transmitting video data over ordinary telephone wires

Apparatus for transmitting moving video information over a single pair of unshielded twisted pair (UTP) wires, comprising:

• 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 one of said first sidebands and to pass the other of said first sidebands, and for producing thereby a first filtered signal having a frequency bandwidth less than a frequency bandwidth of said first FM signal;
• 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.

A video device comprising:

• 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 the input terminal, which modulates the first composite video signal onto a carrier signal and produces thereby a first FM signal comprising a first upper sideband and a first lower sideband each including information from the first color subcarrier;
• a bandpass filter coupled to the FM modulator and having a passband which suppresses one of the first sidebands and passes the other of the first sidebands, and which produces therefrom a first filtered FM signal having a bandwidth less than the first FM signal;
• and
• a transformer coupled between the bandpass filter and the telephone terminal which drives the telephone terminal in accordance with the first filtered FM signal.

A method for transmitting moving video information over a single pair of unshielded twisted pair (UTP) wires, comprising the steps of:

• (1) using a frequency modulation modulator to frequency modulate a carrier signal using a composite moving 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 one of the sidebands and producing thereby a filtered signal having a frequency bandwidth less than a frequency bandwidth of the frequency modulated carrier signal;
• and
• (3) injecting the filtered signal into the single pair of UTP wires.

A video modem comprising:

• an input terminal which accepts a first moving video signal;
• a first telephone terminal connectable to an unshielded twisted pair telephone line;
• an FM modulator, coupled to the input terminal, which frequency modulates the first video signal onto a carrier signal and produces thereby a first FM signal comprising a first upper sideband and a first lower sideband;
• a transformer circuit, coupled to the first telephone terminal, which drives the first telephone terminal in accordance with the first FM signal;
• an output terminal which provides a second moving video signal;
• a receive filter, coupled to the transformer circuit, which isolates the second moving video signal received from the first telephone terminal in a frequency band different from the first FM signal;
• and
• an FM demodulator, coupled to the receive filter and the output terminal, which demodulates signals from the receive filter and provides said signals to the output terminal.