DocumentCode :
1230834
Title :
Subjective Effects of Channel Transmission Errors on PCM and DPCM Voice Communication Systems
Author :
Yan, James ; Donaldson, Robert W.
Author_Institution :
Dept. of Electrical Engineering, Univ. of British Colombia, Vancouver, B.C., Canada
Volume :
20
Issue :
3
fYear :
1972
fDate :
6/1/1972 12:00:00 AM
Firstpage :
281
Lastpage :
290
Abstract :
Isopreference tests were used to study the subjective effects of channel transmission errors on computer-simulated PCM and previous-sample feedback DPCM voice systems. Numerically scaled isopreference contours were obtained and plotted on planes having as axes the number of quantization bits 
and the bit error probability 
of the binary symmetric transmission channel. For any and considered, the quality of DPCM speech was found to exceed that of PCM speech. With fixed and decreasing, the improvement of DPCM relative to PCM increased to the point where quantization noise limited the performance of both systems. Two nonredundant codes, natural binary and folded binary, were used to encode the quantizer output. The two codes yielded comparable speech quality. The maximum subjective quality obtainable for white Gaussian and Rayleigh fading channels was determined as a function of channel capacity. Use of optimum channel encoding was shown to reduce considerably the channel capacity required to obtain a given speech quality. The subjective ratings were compared with measured system signal-to-noise ratios. Finally, the effect of the overload level of the quantizer on the system signal-to-noise ratio was determined.
and the bit error probability of the binary symmetric transmission channel. For any and considered, the quality of DPCM speech was found to exceed that of PCM speech. With fixed and decreasing, the improvement of DPCM relative to PCM increased to the point where quantization noise limited the performance of both systems. Two nonredundant codes, natural binary and folded binary, were used to encode the quantizer output. The two codes yielded comparable speech quality. The maximum subjective quality obtainable for white Gaussian and Rayleigh fading channels was determined as a function of channel capacity. Use of optimum channel encoding was shown to reduce considerably the channel capacity required to obtain a given speech quality. The subjective ratings were compared with measured system signal-to-noise ratios. Finally, the effect of the overload level of the quantizer on the system signal-to-noise ratio was determined.Keywords :
Channel capacity; Computer errors; Error probability; Fading; Feedback; Phase change materials; Quantization; Signal to noise ratio; Speech coding; System testing;
fLanguage :
English
Journal_Title :
Communications, IEEE Transactions on
Publisher :
ieee
ISSN :
0090-6778
Type :
jour
DOI :
10.1109/TCOM.1972.1091187
Filename :
1091187
Link To Document :
