The advantages of PCM in telecommunication systems from the viewpoints of economy, reliability and transmission quality are pointed out. The application of a continuous progression chain code as a correcting transmiss...
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The advantages of PCM in telecommunication systems from the viewpoints of economy, reliability and transmission quality are pointed out. The application of a continuous progression chain code as a correcting transmission code of a PCM system is reported.
A study was made of combining two ways of reducing the redundancy in the digital representation of speech signals. Differential PCM encodes the signal into digital form and reduces the redundancy due to correlation in...
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A study was made of combining two ways of reducing the redundancy in the digital representation of speech signals. Differential PCM encodes the signal into digital form and reduces the redundancy due to correlation in adjacent sample values of the signal. Following this differential PCM operation, entropy coding is used to reduce redundancy due to the unequal probabilities of the quantizer levels to be transmitted.
A DPCM system with adaptive quantization is described. Theoretical considerations on the optimum parameters that determine the quantizer adaptation in order to minimize the quantizing noise are developed. The performa...
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A DPCM system with adaptive quantization is described. Theoretical considerations on the optimum parameters that determine the quantizer adaptation in order to minimize the quantizing noise are developed. The performance of a 32 kbit/sec computer simulation of such a system is shown and the particular type of output quantizing noise examined. Attention is devoted to subjective evaluation of the output quality, even in presence of channel errors.
The transmission of a continuous, random, stationary signal through a pulse-codemodulation system is considered. The distributions of the output signal and of the transmission error are derived for different methods ...
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The transmission of a continuous, random, stationary signal through a pulse-codemodulation system is considered. The distributions of the output signal and of the transmission error are derived for different methods of signal reconstruction at the system output.
By encoding analog data with pulse-code-modulation (PCM) techniques, such problems as tape-deck speed variations, magnetic tape-head wear, tape stretch and head-alignment variations will be eliminated. PCM recording a...
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By encoding analog data with pulse-code-modulation (PCM) techniques, such problems as tape-deck speed variations, magnetic tape-head wear, tape stretch and head-alignment variations will be eliminated. PCM recording also has advantages over fm or am methods because of its accuracy, signal-to-noise ratio, portability, reproducibility, ease of operation and competitive pricing.
This article describes the PCM30, a pulse code modulation system of the primary order, and, as is typical for higher-order systems, the combination of the bit streams of four 30-channel PCM systems within a digital mu...
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This article describes the PCM30, a pulse code modulation system of the primary order, and, as is typical for higher-order systems, the combination of the bit streams of four 30-channel PCM systems within a digital multiplexing equipment to a single bit stream of the second-order system, the PCM 120. The operation of a multiplexer utilizing the pulse stuffing method is explained. With regard to the line equipment for the PCM 120, the principles of operation of a regenerator, the employed line code and the characteristics pertinent to PCM cable with shielded bundles of pairs are investigated.
A method of increasing the efficiency of a pulse-codemodulation communications system with time division of the channels by using the statistical properties of the speech signals is considered. The problems involved ...
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A method of increasing the efficiency of a pulse-codemodulation communications system with time division of the channels by using the statistical properties of the speech signals is considered. The problems involved in constructing such a system are discussed, its efficiency and noise immunity are determined and some theoretical results are given.
This paper examines quantization noise, harmonic and intermodulation distortion, and related power spectra encountered in PCM systems currently utilized in commercial telephony. Performance is evaluated as a function ...
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This paper examines quantization noise, harmonic and intermodulation distortion, and related power spectra encountered in PCM systems currently utilized in commercial telephony. Performance is evaluated as a function of quantization resolution for a number of bit rates, with emphasis on 7- and 8-bit PCM with sampling of speech and sinusoidal inputs at 8,000 Hz. Both uniform and nonuniform quantization are considered.
A DPCM system with adaptive quantization is described. Theoretical considerations on the optimum parameters that determine the quantizer adaptation in order to minimize the quantizing noise are developed. The performa...
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A DPCM system with adaptive quantization is described. Theoretical considerations on the optimum parameters that determine the quantizer adaptation in order to minimize the quantizing noise are developed. The performance of a 32 kbit/sec computer simulation of such a system is shown and the particular type of output quantizing noise examined. Attention is devoted to subjective evaluation of the output quality, even in presence of channel errors.
In transmission systems employing differential PCM (DPCM), errors accumulate at the receiver, making it necessary to transmit the whole value of the variable from time to time. Conversion of the value to be transmitte...
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In transmission systems employing differential PCM (DPCM), errors accumulate at the receiver, making it necessary to transmit the whole value of the variable from time to time. Conversion of the value to be transmitted to normalized form appears to diminish the effects of these errors. The normalized value must be expressed in terms of the limit towards which the signal tends. Reduction of the magnitude of the error is not instantaneous but depends on the signal level and signal fluctuations. In the case of constant level signals, there is no reduction, and the greater the signal amplitude and frequency, the quicker the reduction. Utilization of this coding method must be adapted to individual cases because the quantization interval varies with signal amplitude.
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