Multiple channel upconverter having adjacent channel output and method of implementing the same

• US 6,473,593 B1
• Filed: 12/20/1999
• Issued: 10/29/2002
• Est. Priority Date: 12/20/1999
• Status: Expired due to Term

• Current Assignee: ARRIS Enterprises LLC (CommScope Holding Company, Inc.)
• Original Assignee: General Instrument Corporation (CommScope Holding Company, Inc.)
• Inventors: Groff, Donald E.
• Primary Examiner(s): Congle, Thanh
• Assistant Examiner(s): Nguyen, Thuan T.
• Application Number:
  US09/466,888
• Time in Patent Office: 1,044 Days
• Field of Search: 455/3.01, 455/3.5, 455/463, 455/112, 455/118, 348/724, 348/725, 348/731, 725/131
• US Class Current: 455/3.01
• CPC Class Codes: H03D 7/163 the local oscillations of at least two of the frequency changers being derived from a single oscillator
• CPC Class Codes: H03D 7/165 at least two frequency changers being located in different paths, e.g. in two paths with carriers in quadrature combined with amplitude demodulation H03D1/2245, combined with angle demodulation H03D3/007; N-path filters H03H19/002
• CPC Class Codes: H04N 7/102 Circuits therefor, e.g. noise reducers, equalisers, amplifiers H04N7/108 takes precedence

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.

Claims

1. 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.

2. The upconverter of claim 1, wherein said oscillator signals output by said first-stage oscillators have frequencies that are spaced apart by an amount equal to the frequency spacing between different channels in said cable television system.

3. The upconverter of claim 1, wherein said intermediate frequency of said channel signals when received by said inputs is the same frequency for all of said channel signals.

4. The upconverter of claim 1, further comprising a band pass filtering and amplification stage between said first stage and said second stage.

5. The upconverter of claim 4, wherein said band pass filtering stage comprises a plurality of band pass filters each of which filters one of said channel signals at a particular frequency to which that channel signal has been converted by said first stage.

6. The upconverter of claim 1, further comprising a combiner for combining said plurality of channel signals output by said second stage into a composite signal for broadcast over said cable television system.

7. The upconverter of claim 6, further comprising a low pass filtering and amplification stage between said second stage and said combiner.

8. The upconverter of claim 7, wherein said low pass filtering stage comprises a plurality of band pass filters each of which filters one of said channel signals at a particular frequency to which that channel signal has been converted by said second stage.

9. The upconverter of claim 1, wherein said second-stage oscillator is controllable to control on which channels in the cable system the plurality of channel signals are broadcast.

10. The upconverter of claim 1, further comprising a band pass filtering and amplification stage between said inputs and said first stage.

11. 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.

12. The method of claim 11, further comprising spacing apart frequencies of said oscillator signals by an amount equal to the frequency spacing between different channels in said cable television system.

13. The method of claim 11, further comprising supplying all of said channel signals to said first stage with a common intermediate frequency.

14. The method of claim 11, further comprising band pass filtering and amplifying said channel signals between said first stage and said second stage.

15. The method of claim 14, wherein said band pass filtering further comprises band pass filtering each of said channel signals with a separate band pass filter at a particular frequency to which that channel signal has been converted by said first stage.

16. The method of claim 11, further comprising combining said plurality of channel signals output by said second stage into a composite signal for broadcast over said cable television system.

17. The method of claim 16, further comprising band pass filtering and amplifying said channel signals between said second stage and said combiner.

18. The method of claim 17, wherein said band pass filtering further comprises band pass filtering each of said channel signals with a separate band pass filter at a particular frequency to which that channel signal has been converted by said second stage.

19. The method of claim 11, further comprising controlling said second-stage oscillator to control on which channels in said cable system said plurality of channel signals are broadcast.

20. The method of claim 11, further comprising band pass filtering and amplifying said channel signals before inputting said channel signals to said first stage.

21. 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.