Signal distribution system

• US 3,894,177 A
• Filed: 03/23/1973
• Issued: 07/08/1975
• Est. Priority Date: 03/23/1973
• Status: Expired due to Term

• Current Assignee: Eric R. Woods, Norman E. Howell, Russell G. Thompson
• Original Assignee: Eric R. Woods, Norman E. Howell, Russell G. Thompson
• Inventors: Thompson, Russell G., Woods, Eric R., Howell, Norman E.
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Psitos, Aristotelis M.
• Application Number:
  US05/344,374
• Time in Patent Office: 837 Days
• Field of Search: 325/308 178/DIG.13,DIG.23,5.6R 179/15AQ,15A,15BS,15BP,15BM,18GF,15AL
• US Class Current: 348/485
• CPC Class Codes: H04N 5/268 Signal distribution or switching

Abstract

A system for distributing and routing a large number of audiovideo signal channels is described. The system includes an input multiplexer and signal distribution networks, a matrix of switch groups and an output demultiplexer. In the input multiplexer the audio signals accompanying each video signal in each channel are digitized and the resulting digital signal angularly modulated to produce signals modulated by the digital signals and translated to a frequency region above the region of the video. A composite signal including the video and the angularly modulated audio signals are applied to the input distribution networks to drive a matrix of switch groups. Each output of the matrix switch has as many selectable inputs as there are input channels. Outputs are organized in groups to facilitate input distribution. Inputs are organized in blocks to facilitate input selection. An output demultiplexer is provided for each output and reconstructs the video and audio signals which are routed thereto by the matrix switch.

Claims

1. For use iN a television terminal or the like having switching means for distributing a plurality of input channels to a plurality of outputs, said input channels each including a plurality of analog signals, one of which is a video signal which occupies a certain frequency baseband and another of which is another analog signal, multiplexing apparatus for each of said channels which comprise:

a. means for converting at least said other analog signal into digital signals, b. means responsive to said digital signals for providing a modulated signal corresponding thereto in a frequency band displaced above the band of said video signal, c. means for additively combining said video signal and said modulated signal to provide a multiplexed signal with the video signal accompanying said modulated signal, said video signal occupying its baseband and the modulated signal corresponding to said other analog signal a band above said baseband, and d. means for applying said multiplexed signal from said combining means separately in its respective input channel to said switching means.

2. The invention as set forth in claim 1 further comprising for each said outputs a demultiplexing system which comprises a. frequency responsive means for separating said modulated signal from its said accompanying video signal, b. means for reconstructing said digital signals from said separated modulated signal, and c. means for converting said reconstructed digital signals into analog form.

3. The invention as set forth in claim 1 wherein said analog signals include a plurality of audio signals, and said converting means including means for translating said audio signals into a serial train of pulses which provides said digital signal.

4. The invention as set forth in claim 1 wherein said modulated signal providing means includes a phase modulator, means for applying to said phase modulator a carrier signal having a frequency higher that the highest frequency of said video signal baseband, and means for also applying said digital signals to said phase modulator.

5. The invention as set forth in claim 1 wherein said plurality of analog signals includes said video and an audio signal, an analog to digital converter means responsive to said audio signal for providing a serial stream of pulses representing said audio signal in digital form, a source of carrier signals having a frequency higher than the highest significant baseband component of said video signal, a phase modulator to which said source is coupled, said pulses being applied to said modulator to modulate said carrier, and means applying the output of said modulator and said video signal to said additively combining means.

6. The invention as set forth in claim 5 wherein said analog signals include a plurality of audio signals, a plurality of said analog to digital converter means each for a separate one of said audio signals, a register, programming means for successively loading the said analog to digital converters to said register, and means for reading out of said register to provide said serial stream of pulses.

7. The invention as set forth in claim 6 including means responsive to said carrier signals for providing clock pulses of different repetition rate, including clock pulses of higher rate and of lower rate, means for applying said clock pulses of higher rate to said register to read out said register and means for applying said clock pulses of lower rate to said programming means.

8. The invention as set forth in claim 1 including demultiplexing means for said signals which comprise frequency selective means for separating said video signal from said modulated digital signals, a phase locked loop responsive to said modulated signal for demodulating said signal into said digital signal and for constructing said clock signals, a register, means operated by said clock signal for transferring said digital signal serially into said register, a plurality of digital to anaLog converters, and control means also responsive to said clock signals and to the contents of said register for successively transferring the contents of said register to different ones of said digital to analog converters, and means responsive to the outputs of said digital to analog converters for providing each of said plurality of audio signals.