Multiple channel upconverter having adjacent channel output and method of implementing the same
AssigneeGeneral Instruments Corporation
InventorDonald E. Groff
Life of this patent
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Abstract
An upconverter unit for a cable television system upconverts multiple channel signals from a common intermediate frequency to a VHF or UHF signal ready for transmission to subscribers. The two-stage upconverter provides a first stage in which different channel signals are upconverted to different frequencies which are spaced apart by same frequency difference characteristic of different channels in the cable system. A second stage of the upconverter uses a common oscillator signal to convert the various channel signals from the first stage to the frequencies at which they will be transmitted over the cable system.
Claims21
A multiple-channel, two stage upconverter for processing television channel signals prior to broadcast in a cable television system, the upconverter comprising:
- a plurality of inputs for receiving a corresponding plurality of channel signals at an intermediate frequency;
- a first stage comprising a plurality of mixers and oscillators, one mixer and oscillator being associated with and receiving each of said channel signals, wherein each of said oscillators outputs an oscillator signal having a frequency different from oscillator signals output by other first-stage oscillators, and further wherein each oscillator signal is mixed by an associated mixer with one of said channel signals;
- a second stage receiving said channel signals from said first stage, said second stage comprising a plurality of second-stage mixers each of which receives one of said channel signals from said first stage, wherein each of said second-stage mixers mixes a received channel signal with a second-stage oscillator signal output by a single second-stage oscillator which is connected to each of said second-stage mixers.
A method of upconverting multiple television channel signals using a two stage technique prior to broadcast of the channel signals in a cable television system, the method comprising:
- in a first stage, mixing each of said channel signals with one of a plurality of oscillator signals, wherein each of said oscillator signals has a frequency different other oscillator signals of said plurality of oscillator signals;
- and
- in a second stage, mixing each of said channel signals individually with a common second-stage oscillator signal.
An upconverter for upconverting multiple television channel signals using a two stage technique prior to broadcast of the channel signals in a cable television system, the method comprising:
- first means for converting said plurality of channel signals such that said channel signals each have a different frequency, wherein said frequencies of said channel signals are spaced by an amount equal to a frequency spacing between channels in said cable television system;
- and
- second means for converting said plurality of channel signals to frequencies at which channels are broadcast in said cable television system using a single, common oscillator signal.
Dependencies are inferred from the claim text.