Pub Date : 1978-05-06DOI: 10.1002/J.1538-7305.1978.TB02102.X
N. F. Dinn, G. A. Zimmerman
The design and realization of 19-GHz and 29-GHz beacon receivers for implementation of the remote site diversity reception experiment are discussed. The experiment objectives and constraints are investigated in terms of their impact on equipment realization. Data acquisition and retrieval problems associated with remote sites are also addressed. Finally, some of the results obtained from early operation are presented. These results, obtained from direct measurement of the beacons, correlate very well with earlier radiometer measurements scaled in frequency with appropriate corrections made for the impact of energy scattering due to rain.
{"title":"COMSTAR experiment: COMSTAR beacon receiver diversity experiment","authors":"N. F. Dinn, G. A. Zimmerman","doi":"10.1002/J.1538-7305.1978.TB02102.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1978.TB02102.X","url":null,"abstract":"The design and realization of 19-GHz and 29-GHz beacon receivers for implementation of the remote site diversity reception experiment are discussed. The experiment objectives and constraints are investigated in terms of their impact on equipment realization. Data acquisition and retrieval problems associated with remote sites are also addressed. Finally, some of the results obtained from early operation are presented. These results, obtained from direct measurement of the beacons, correlate very well with earlier radiometer measurements scaled in frequency with appropriate corrections made for the impact of energy scattering due to rain.","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1978-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"119932874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1978-04-01DOI: 10.1109/ICASSP.1978.1170566
B. McDermott, C. Scagliola, D. Goodman
An experiment has been performed to study the perceptual characteristics of speech processed by adaptive differential PCM. We created 18 three-bit and four-bit coders spanning a wide range of quantizer adaptation parameters. Subjects judged differences between coders and rated the quality of each coder individually. The difference data reveal three important perceptual characteristics: overall clarity, signal vs. background degradation, and rough vs. smooth impairment. These characteristics are strongly correlated with coder design parameters and objective performance measures. Overall subjective quality is well predicted by segmental signal-to-noise ratio and even better by a linear combination of measures of granular distortion and overload distortion.
{"title":"Perceptual and objective evaluation of speech processed by adaptive differential pcm","authors":"B. McDermott, C. Scagliola, D. Goodman","doi":"10.1109/ICASSP.1978.1170566","DOIUrl":"https://doi.org/10.1109/ICASSP.1978.1170566","url":null,"abstract":"An experiment has been performed to study the perceptual characteristics of speech processed by adaptive differential PCM. We created 18 three-bit and four-bit coders spanning a wide range of quantizer adaptation parameters. Subjects judged differences between coders and rated the quality of each coder individually. The difference data reveal three important perceptual characteristics: overall clarity, signal vs. background degradation, and rough vs. smooth impairment. These characteristics are strongly correlated with coder design parameters and objective performance measures. Overall subjective quality is well predicted by segmental signal-to-noise ratio and even better by a linear combination of measures of granular distortion and overload distortion.","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"222 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1978-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124246335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1977-05-06DOI: 10.1109/ICASSP.1977.1170340
R. Crochiere, M. Sambur
The standard fixed sub-band coding scheme has been modified to allow the center frequency of the two upper bands to vary in accordance with the dynamic movement of the vocal tract resonances F2 and F3. A relatively simple zero-crossing technique is used to measure the formants F2 and F3. Through the use of this variable band coder, it is possible to produce moderate-quality, intelligible speech at 4.8 kb/s (quality is slightly less than that of a 7.2-kb/s fixed sub-band coder and equal to that of about a 16-kb/s adm coder). The reasonably good intelligibility of the 4.8-kb/s variable-band coded speech can be attributed to the coders attempt to capture and encode those spectral components of the signal that are perceptually most significant (the region around the formants). The major advantage of the variable-band scheme is that its implementation is considerably less complex than other waveform coding schemes or vocoder systems that can produce intelligible, narrowband speech.
{"title":"A variable-band coding Scheme for speech encoding at 4.8 kb/s","authors":"R. Crochiere, M. Sambur","doi":"10.1109/ICASSP.1977.1170340","DOIUrl":"https://doi.org/10.1109/ICASSP.1977.1170340","url":null,"abstract":"The standard fixed sub-band coding scheme has been modified to allow the center frequency of the two upper bands to vary in accordance with the dynamic movement of the vocal tract resonances F2 and F3. A relatively simple zero-crossing technique is used to measure the formants F2 and F3. Through the use of this variable band coder, it is possible to produce moderate-quality, intelligible speech at 4.8 kb/s (quality is slightly less than that of a 7.2-kb/s fixed sub-band coder and equal to that of about a 16-kb/s adm coder). The reasonably good intelligibility of the 4.8-kb/s variable-band coded speech can be attributed to the coders attempt to capture and encode those spectral components of the signal that are perceptually most significant (the region around the formants). The major advantage of the variable-band scheme is that its implementation is considerably less complex than other waveform coding schemes or vocoder systems that can produce intelligible, narrowband speech.","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"155 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1977-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115971097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1976-04-12DOI: 10.1109/ICASSP.1976.1170079
R. Crochiere, S. A. Webber, J. Flanagan
A rationale is advanced for digitally coding speech signals in terms of sub-bands of the total spectrum. The approach provides a means for controlling and reducing quantizing noise in the coding. Each sub-band is quantized with an accuracy (bit allocation) based upon perceptual criteria. As a result, the quality of the coded signal is improved over that obtained from a single full-band coding of the total spectrum. In one implementation, the individual sub-bands are low-pass translated before coding. In another, “integer-band” sampling is employed to alias the signal in an advantageous way before coding. Other possibilities extend to complex demodulation of the sub-bands, and to representing the sub-band signals in terms of envelopes and phase-derivatives. In all techniques, adaptive quantization is used for the coding, and a parsimonious allocation of bits is made across the bands. Computer simulations are made to demonstrate the signal qualities obtained for codings at 16 and 9.6 kb/s.
{"title":"Digital coding of speech in sub-bands","authors":"R. Crochiere, S. A. Webber, J. Flanagan","doi":"10.1109/ICASSP.1976.1170079","DOIUrl":"https://doi.org/10.1109/ICASSP.1976.1170079","url":null,"abstract":"A rationale is advanced for digitally coding speech signals in terms of sub-bands of the total spectrum. The approach provides a means for controlling and reducing quantizing noise in the coding. Each sub-band is quantized with an accuracy (bit allocation) based upon perceptual criteria. As a result, the quality of the coded signal is improved over that obtained from a single full-band coding of the total spectrum. In one implementation, the individual sub-bands are low-pass translated before coding. In another, “integer-band” sampling is employed to alias the signal in an advantageous way before coding. Other possibilities extend to complex demodulation of the sub-bands, and to representing the sub-band signals in terms of envelopes and phase-derivatives. In all techniques, adaptive quantization is used for the coding, and a parsimonious allocation of bits is made across the bands. Computer simulations are made to demonstrate the signal qualities obtained for codings at 16 and 9.6 kb/s.","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116002754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1976-04-01DOI: 10.1109/ICASSP.1976.1170050
D. Goodman, B. McDermott, L. Nakatani
Subjective quality ratings of pcm coded speech were obtained with the aims of (i) determining the effects of certain coder parameters and their interactions on speech quality, (ii) finding objective measures for predicting perceived distortions, and (iii) providing guidelines for optimizing coder design. Coders with various combinations of four clipping levels, seven step sizes, four bandwidths, and three logarithmic companding laws were simulated. The coders were rated for quality on a 10-point scale by 48 listeners who heard male and female speech processed by the coders. The ratings depended strongly on clipping level and step size, but only weakly on bandwidth. None of the coder parameters interacted strongly with another. Clipping noise power grossly overestimated the extent of perceived overload distortion; instead, clipping percentage is proposed as a much more realistic predictor. Signal-to-granular-noise ratio was a good predictor of perceived granular noise. For a given bit rate, the coder with the highest quality rating was not the coder with minimum total clipping and granular noise power, contrary to traditional wisdom.
{"title":"Subjective evaluation of pcm coded speech","authors":"D. Goodman, B. McDermott, L. Nakatani","doi":"10.1109/ICASSP.1976.1170050","DOIUrl":"https://doi.org/10.1109/ICASSP.1976.1170050","url":null,"abstract":"Subjective quality ratings of pcm coded speech were obtained with the aims of (i) determining the effects of certain coder parameters and their interactions on speech quality, (ii) finding objective measures for predicting perceived distortions, and (iii) providing guidelines for optimizing coder design. Coders with various combinations of four clipping levels, seven step sizes, four bandwidths, and three logarithmic companding laws were simulated. The coders were rated for quality on a 10-point scale by 48 listeners who heard male and female speech processed by the coders. The ratings depended strongly on clipping level and step size, but only weakly on bandwidth. None of the coder parameters interacted strongly with another. Clipping noise power grossly overestimated the extent of perceived overload distortion; instead, clipping percentage is proposed as a much more realistic predictor. Signal-to-granular-noise ratio was a good predictor of perceived granular noise. For a given bit rate, the coder with the highest quality rating was not the coder with minimum total clipping and granular noise power, contrary to traditional wisdom.","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127615859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1975-10-01DOI: 10.1109/ICASSP.1976.1170047
P. Cummiskey
An estimate of optimum performance is derived for a single-integration, adaptive delta modulator. Several simulations of adaptive delta modulators with single integrators have all produced signal-to-noise ratios near or below the estimate. The derivations presented here indicate that the performance of a single-integration delta modulator is dependent on the correlation between adjacent samples of the input signal and on the probability density function of its derivative. The relationship between the probability density of the derivative of the input signal and optimum performance, in turn, explains why signal-to-noise ratios taken on sine waves are greater than those recorded while processing speech signals.
{"title":"Single-integration, adaptive delta modulation","authors":"P. Cummiskey","doi":"10.1109/ICASSP.1976.1170047","DOIUrl":"https://doi.org/10.1109/ICASSP.1976.1170047","url":null,"abstract":"An estimate of optimum performance is derived for a single-integration, adaptive delta modulator. Several simulations of adaptive delta modulators with single integrators have all produced signal-to-noise ratios near or below the estimate. The derivations presented here indicate that the performance of a single-integration delta modulator is dependent on the correlation between adjacent samples of the input signal and on the probability density function of its derivative. The relationship between the probability density of the derivative of the input signal and optimum performance, in turn, explains why signal-to-noise ratios taken on sine waves are greater than those recorded while processing speech signals.","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1975-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125651633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1975-02-01DOI: 10.1109/ISSCC.1975.1155433
I. Tatsuguchi, J. Gewartowski
An experimental 10-W, three-stage, GaAs IMPATT amplifier has been developed with transmission characteristics suitable for use in 6-GHz long-haul radio-relay systems. The amplifier uses five flat-doping-profile GaAs IMPATT diodes in three cascaded, circulator-coupled stages. The dc input power is 153 W with a nominal 10 W of output power and an overall noise figure of less than 35 dB. The overall amplifier efficiency is 6.5 percent. The major portion of the amplifier is constructed in strip transmission line using suspended alumina substrate in an aluminum housing. Small, integrated, coaxial sections with coaxial transformers connect the diodes to the strip transmission line circuits. The amplifier is cooled by free convection.
{"title":"A 10-w, 6-GHz, gaas impatt amplifier for microwave Radio systems","authors":"I. Tatsuguchi, J. Gewartowski","doi":"10.1109/ISSCC.1975.1155433","DOIUrl":"https://doi.org/10.1109/ISSCC.1975.1155433","url":null,"abstract":"An experimental 10-W, three-stage, GaAs IMPATT amplifier has been developed with transmission characteristics suitable for use in 6-GHz long-haul radio-relay systems. The amplifier uses five flat-doping-profile GaAs IMPATT diodes in three cascaded, circulator-coupled stages. The dc input power is 153 W with a nominal 10 W of output power and an overall noise figure of less than 35 dB. The overall amplifier efficiency is 6.5 percent. The major portion of the amplifier is constructed in strip transmission line using suspended alumina substrate in an aluminum housing. Small, integrated, coaxial sections with coaxial transformers connect the diodes to the strip transmission line circuits. The amplifier is cooled by free convection.","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1975-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115306006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An important problem in speech processing is to detect the presence of speech in a background of noise. This problem is often referred to as the endpoint location problem. By accurately detecting the beginning and end of an utterance, the amount of processing of speech data can be kept to a minimum. The algorithm proposed for locating the endpoints of an utterance is based on two measures of the signal, zero crossing rate and energy. The algorithm is inherently capable of performing correctly in any reasonable acoustic environment in which the signal-to-noise ratio is on the order of 30 dB or better. The algorithm has been tested over a variety of recording conditions and for a large number of speakers and has been found to perform well across all tested conditions.
{"title":"An algorithm for determining the endpoints of isolated utterances","authors":"L. Rabiner, M. Sambur","doi":"10.1121/1.1914118","DOIUrl":"https://doi.org/10.1121/1.1914118","url":null,"abstract":"An important problem in speech processing is to detect the presence of speech in a background of noise. This problem is often referred to as the endpoint location problem. By accurately detecting the beginning and end of an utterance, the amount of processing of speech data can be kept to a minimum. The algorithm proposed for locating the endpoints of an utterance is based on two measures of the signal, zero crossing rate and energy. The algorithm is inherently capable of performing correctly in any reasonable acoustic environment in which the signal-to-noise ratio is on the order of 30 dB or better. The algorithm has been tested over a variety of recording conditions and for a large number of speakers and has been found to perform well across all tested conditions.","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1974-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125439857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
UNIX∗ is a general-purpose, multi-user, interactive operating system for the larger Digital Equipment Corporation PDP-11 and the Interdata 8/32 computers. It offers a number of features seldom found even in larger operating systems, including (i) A hierarchical file system incorporating demountable volumes, (ii) Compatible file, device, and inter-process I/O, (iii) The ability to initiate asynchronous processes, (iv) System command language selectable on a per-user basis, (v) Over 100 subsystems including a dozen languages, (vi) High degree of portability. This paper discusses the nature and implementation of the file system and of the user command interface.
{"title":"The UNIX time-sharing system","authors":"D. Ritchie, K. Thompson","doi":"10.1145/361011.361061","DOIUrl":"https://doi.org/10.1145/361011.361061","url":null,"abstract":"UNIX∗ is a general-purpose, multi-user, interactive operating system for the larger Digital Equipment Corporation PDP-11 and the Interdata 8/32 computers. It offers a number of features seldom found even in larger operating systems, including (i) A hierarchical file system incorporating demountable volumes, (ii) Compatible file, device, and inter-process I/O, (iii) The ability to initiate asynchronous processes, (iv) System command language selectable on a per-user basis, (v) Over 100 subsystems including a dozen languages, (vi) High degree of portability. This paper discusses the nature and implementation of the file system and of the user command interface.","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1974-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125512815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.15325/tbstj.1980.6779707
{"title":"Papers by bell laboratories authors","authors":"","doi":"10.15325/tbstj.1980.6779707","DOIUrl":"https://doi.org/10.15325/tbstj.1980.6779707","url":null,"abstract":"","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130303562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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