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Quantized pulse modulated nonsynchronous clipped speech multi-channel coded communication system

  • US 4,070,550 A
  • Filed: 06/28/1961
  • Issued: 01/24/1978
  • Est. Priority Date: 06/28/1961
  • Status: Expired due to Term
First Claim
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1. A quantized pulse-modulated nonsynchronous clipped speech multi-channel coded communication system comprising transmitter terminals and receiver terminals;

  • said transmitter terminals comprising a plurality of channel units, a timing unit, and a transmitting unit;

    said channel unit including processing section, encoding section and pulse position modulating section;

    said processing section including input means for coupling a composite waveform thereto, preemphasis means operatively receiving said composite waveform for accentuating crossover points in the composite waveform, clipping means operatively receiving the output of said preemphasis means for infinitely clipping the amplitude portion of said composite waveform and retaining the frequency information therein, pulse generating means operatively coupled to the output of said clipping means for generating pulses corresponding to said crossover points;

    gate generator means contained within said encoding section and operatively coupled to the output of said pulse generating means for generating gate pulses;

    buffer circuit means contained within said timing unit operatively connected to the output of said gate generator means for isolating the outputs of said plurality of channel units, sampling means for sampling the outputs of said channel units fed to said buffer circuit means, first coincidence circuit means operatively receiving the output of said buffer circuit means and said sampling means for generating an output pulse when pulses from said summing circuit and said sampling means are coincident therein, channel coding means comprising a delay line operatively receiving pulses from said coincidence circuit means for generating start stop and a plurality of channel pulses corresponding to the number of channel units;

    second coincidence circuit means operatively receiving pulses from said gate generating means and pulses from said delay line corresponding to the appropriate channel unit for generating an output pulse when pulses from said gate generator and said delay line are coincident therein, blocking oscillator means operatively receiving pulses from the output of said second coincidence circuit means for generating first output pulse which is operatively coupled to said gate generator means for turning off said gate generating means and generating a second pulse;

    comparator means in said position modulator section and operatively receiving the second output pulse from said blocking oscillator and receiving a signal corresponding to said composite waveform and time modulating said second output pulse from said blocking oscillator wherein the modulation corresponds to the amplitude information of the input waveform;

    other buffer circuit means contained within said transmitting unit for receiving start-stop pulses from said delay line and time modulated channel pulses from said comparator means wherein said channel pulses are contained between said start-stop pulses, and propagating means operatively receiving the output trains of pulses from said other buffer circuit means for propagating said trains of pulses;

    said receiver terminal comprising a receiver unit for receiving and detecting trains of pulses;

    master decoder means operatively receiving trains of pulses from said receiver unit for separating incoming trains of pulses into channels and for generating a time reference pulse;

    at least one channel decoder means including coincidence means operatively receiving pulses from said master decoder means for determining the presence of information on a particular channel by comparing said reference pulse to individual channel pulses in the coincidence means;

    at least one reprocessing means operatively receiving pulses from said channel decoder means for converting information applying to a particular channel from pulses to a reproduction of the originating signals;

    each reprocessing unit including pulse position demodulator means operatively receiving pulses from said channel decoder means for converting time modulation information to a DC voltage which is proportional to the amplitude information;

    a clipped speech section contained within said audio reprocessing means operatively receiving output pulses from said channel decoder means for recovering the frequency information contained therein;

    variable amplifier means operatively receiving amplitude information from said pulse position demodulator means and audio frequency information from said clipped speech means for combining said amplitude information and said frequency information thereby improving the naturalness of the output speech and audio output means operatively receiving the output of said variable amplifier means for reproducing said output waveform from said variable amplifier means.

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