Pub Date : 1982-03-01DOI: 10.1002/J.1538-7305.1982.TB03409.X
S. Ahamed
Rate changing occurs whenever sequences of data undergo transformations in rate without undergoing a change in the order of sequence. When the ratio of transformation is not an integer, fractional rate changes are necessary. These are generally, a prerequisite for the time-compression multiplexing mode of data transmission. Zero or minimal delay is a desirable characteristic, for example, in reducing the annoyance from the far-end echo whenever voice is encoded and transmitted. Conventional fractional rate changing entails an inherent delay in the rate change circuits. Segmenting shift registers reduces the delay of the last bit without completely eliminating it, unless the shift-register length is reduced to one bit. In this paper, a method of partitioning the shift registers by logarithmic counts is developed to reduce the complexity of the gating and the counting circuits. Zero last-bit delays are attainable in all cases where the rate increase is greater than two or, conversely, the rate reduction is less than half. For the remaining cases, the compromise between circuit complexity and the last-bit delay is outlined.
{"title":"A general class of zero- or minimum-delay fractional rate change circuits","authors":"S. Ahamed","doi":"10.1002/J.1538-7305.1982.TB03409.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1982.TB03409.X","url":null,"abstract":"Rate changing occurs whenever sequences of data undergo transformations in rate without undergoing a change in the order of sequence. When the ratio of transformation is not an integer, fractional rate changes are necessary. These are generally, a prerequisite for the time-compression multiplexing mode of data transmission. Zero or minimal delay is a desirable characteristic, for example, in reducing the annoyance from the far-end echo whenever voice is encoded and transmitted. Conventional fractional rate changing entails an inherent delay in the rate change circuits. Segmenting shift registers reduces the delay of the last bit without completely eliminating it, unless the shift-register length is reduced to one bit. In this paper, a method of partitioning the shift registers by logarithmic counts is developed to reduce the complexity of the gating and the counting circuits. Zero last-bit delays are attainable in all cases where the rate increase is greater than two or, conversely, the rate reduction is less than half. For the remaining cases, the compromise between circuit complexity and the last-bit delay is outlined.","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"2012 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120407785","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 : 1981-05-06DOI: 10.1007/978-1-4612-5798-1_20
J. McKenna, Debasis Mitra, K. G. Ramakrishnan
{"title":"A class of closed Markovian queuing networks: integral representations, asymptotic expansions, and generalizations","authors":"J. McKenna, Debasis Mitra, K. G. Ramakrishnan","doi":"10.1007/978-1-4612-5798-1_20","DOIUrl":"https://doi.org/10.1007/978-1-4612-5798-1_20","url":null,"abstract":"","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1981-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130436710","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 : 1980-03-01DOI: 10.1017/S0001867800050163
L. Shepp, D. Slepian, A. Wyner
Let {Xn} be a discrete-time stationary moving-average process having the representation where the real-valued process (Yn) has a well-defined entropy and spectrum. Let ∊∗2k denote the smallest mean-squared error of any estimate of Xn based on observations of Xn–1, Xn–2, …, Xn–k, and let ∊∗2klin, be the corresponding least mean-squared error when the estimator is linear in the k observations. We establish an inequality of the form where G(Y) ≤ 1 depends only on the entropy and spectrum of {Yn}. We also obtain explicit formulas for ∊∗2k and ∊∗2klin and compare these quantities graphically when M = 2 and the {Yn} are i.i.d. variates with one of several different distributions. The best estimators are quite complicated but are frequently considerably better than the best linear ones. This extends a result of M. Kanter.
{"title":"On prediction of moving-average processes","authors":"L. Shepp, D. Slepian, A. Wyner","doi":"10.1017/S0001867800050163","DOIUrl":"https://doi.org/10.1017/S0001867800050163","url":null,"abstract":"Let {X<inf>n</inf>} be a discrete-time stationary moving-average process having the representation where the real-valued process (Y<inf>n</inf>) has a well-defined entropy and spectrum. Let ∊<sup>∗2</sup><inf>k</inf> denote the smallest mean-squared error of any estimate of X<inf>n</inf> based on observations of X<inf>n–1</inf>, X<inf>n–2</inf>, …, X<inf>n–k</inf>, and let ∊<sup>∗2</sup><inf>klin</inf>, be the corresponding least mean-squared error when the estimator is linear in the k observations. We establish an inequality of the form where G(Y) ≤ 1 depends only on the entropy and spectrum of {Y<inf>n</inf>}. We also obtain explicit formulas for ∊<sup>∗2</sup><inf>k</inf> and ∊<sup>∗2</sup><inf>klin</inf> and compare these quantities graphically when M = 2 and the {Y<inf>n</inf>} are i.i.d. variates with one of several different distributions. The best estimators are quite complicated but are frequently considerably better than the best linear ones. This extends a result of M. Kanter.","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1980-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117176694","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 : 1979-11-01DOI: 10.1109/ICASSP.1980.1171018
S. Levinson, K. Shipley
We describe a conversational-mode, speech-understanding system which enables its user to make airline reservations and obtain timetable information through a spoken dialog. The system is structured as a three-level hierarchy consisting of an acoustic word recognizer, a syntax analyzer, and a semantic processor. The semantic level controls an audio response system making two-way speech communication possible. The system is highly robust and operates on-line in a few times real time on a laboratory minicomputer. The speech communication channel is a standard telephone set connected to the computer by an ordinary dialed-up line.
{"title":"A conversational-mode airline information and reservation system using speech input and output","authors":"S. Levinson, K. Shipley","doi":"10.1109/ICASSP.1980.1171018","DOIUrl":"https://doi.org/10.1109/ICASSP.1980.1171018","url":null,"abstract":"We describe a conversational-mode, speech-understanding system which enables its user to make airline reservations and obtain timetable information through a spoken dialog. The system is structured as a three-level hierarchy consisting of an acoustic word recognizer, a syntax analyzer, and a semantic processor. The semantic level controls an audio response system making two-way speech communication possible. The system is highly robust and operates on-line in a few times real time on a laboratory minicomputer. The speech communication channel is a standard telephone set connected to the computer by an ordinary dialed-up line.","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128513116","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}
High resolution and steep profile patterns have been generated in a 2.6-μm thick organic layer which conforms to the steps on a wafer surface and is planar on its top. This thick organic layer (a photoresist in the present experiments) is covered with an intermediate layer of SiO2 and a top, thin layer of X-ray or photoresist. After exposure and development of the top resist layer, the intermediate layer is etched by CHF3 reactive ion etching. The thick organic layer is then etched by O2 reactive ion etching. Submicron resolution with essentially vertical walls in the thick organic material was achieved. The technique is also applicable to photo- and electron lithography. It reduces the need for thick resist patterns for the lithography step and, at the same time, ensures high resolution combined with good step coverage.
{"title":"High resolution, steep profile, resist patterns","authors":"J. Moran, D. Maydan","doi":"10.1116/1.570256","DOIUrl":"https://doi.org/10.1116/1.570256","url":null,"abstract":"High resolution and steep profile patterns have been generated in a 2.6-μm thick organic layer which conforms to the steps on a wafer surface and is planar on its top. This thick organic layer (a photoresist in the present experiments) is covered with an intermediate layer of SiO2 and a top, thin layer of X-ray or photoresist. After exposure and development of the top resist layer, the intermediate layer is etched by CHF3 reactive ion etching. The thick organic layer is then etched by O2 reactive ion etching. Submicron resolution with essentially vertical walls in the thick organic material was achieved. The technique is also applicable to photo- and electron lithography. It reduces the need for thick resist patterns for the lithography step and, at the same time, ensures high resolution combined with good step coverage.","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115521069","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 : 1979-04-01DOI: 10.1109/ICASSP.1979.1170681
F. Pirz
Directional microphones have long been proposed for the removal of room reverberation. An array microphone would seem ideal for this purpose, since theoretically it can be aimed anywhere within the room. However, microphone pattern beamwidth is related to wavelength and aperture size. For a fixed-size aperture, as wavelength goes down so does beamwidth. The change in beamwidth over a decade change in wavelength would seem to be unacceptable for this application. We discuss the design of a constant beamwidth array microphone for the frequency range 300 to 3000 Hz. Because the microphone-to-talker distance is assumed to be about 3 ft while the array has a 9-ft aperture, the microphone is optimized for near field. We also discuss the use of a nonlinear optimization program for choosing the array parameters.
{"title":"Design of a wideband, constant beamwidth, array microphone for use in the near field","authors":"F. Pirz","doi":"10.1109/ICASSP.1979.1170681","DOIUrl":"https://doi.org/10.1109/ICASSP.1979.1170681","url":null,"abstract":"Directional microphones have long been proposed for the removal of room reverberation. An array microphone would seem ideal for this purpose, since theoretically it can be aimed anywhere within the room. However, microphone pattern beamwidth is related to wavelength and aperture size. For a fixed-size aperture, as wavelength goes down so does beamwidth. The change in beamwidth over a decade change in wavelength would seem to be unacceptable for this application. We discuss the design of a constant beamwidth array microphone for the frequency range 300 to 3000 Hz. Because the microphone-to-talker distance is assumed to be about 3 ft while the array has a 9-ft aperture, the microphone is optimized for near field. We also discuss the use of a nonlinear optimization program for choosing the array parameters.","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130760365","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 : 1978-10-01DOI: 10.1109/EUMA.1978.332580
J. Irvin, A. Loya
The degradation and failure of low-noise GaAs FETs have been accelerated by various stress-aging techniques including storage at elevated temperatures with and without bias, exposure to humid atmospheres with and without bias, and temperature cycling. Several time-temperature-bias-induced catastrophic failure mechanisms have been observed, all involving the Al gate metallization. These mechanisms are Au-Al phase formation, Al electromigration, and electrolytic corrosion. Each of these processes results ultimately in an open gate. Accelerated aging also produces gradual, long-term degradation in both dc and RF characteristics, though the two are not always correlated. In fact, contrary to some expectations, contact resistance may increase almost two orders of magnitude without significant degradation in the noise figure or gain of a low-noise transistor. Besides contact resistance, other mechanisms such as traps in the channel are thought to play a role in the degradation of RF properties. It was found that all the important degradation mechanisms are bias-sensitive and that aging without bias gives erroneously long lifetime projections. The cumulative failure distributions for the mechanisms observed approximate a log-normal relation with standard deviations between 0.6 and 1.4. The relevant degradation or failure processes have activation energies near 1.0 eV, which give rise to projected median lifetimes at 60°C (channel temperature) over 107 hours and corresponding failure rates (excepting infant mortality) under 40 FITs (40 per 109 device-hours) at 20 years of service.
{"title":"Failure mechanisms and reliability of low-noise gaas fets","authors":"J. Irvin, A. Loya","doi":"10.1109/EUMA.1978.332580","DOIUrl":"https://doi.org/10.1109/EUMA.1978.332580","url":null,"abstract":"The degradation and failure of low-noise GaAs FETs have been accelerated by various stress-aging techniques including storage at elevated temperatures with and without bias, exposure to humid atmospheres with and without bias, and temperature cycling. Several time-temperature-bias-induced catastrophic failure mechanisms have been observed, all involving the Al gate metallization. These mechanisms are Au-Al phase formation, Al electromigration, and electrolytic corrosion. Each of these processes results ultimately in an open gate. Accelerated aging also produces gradual, long-term degradation in both dc and RF characteristics, though the two are not always correlated. In fact, contrary to some expectations, contact resistance may increase almost two orders of magnitude without significant degradation in the noise figure or gain of a low-noise transistor. Besides contact resistance, other mechanisms such as traps in the channel are thought to play a role in the degradation of RF properties. It was found that all the important degradation mechanisms are bias-sensitive and that aging without bias gives erroneously long lifetime projections. The cumulative failure distributions for the mechanisms observed approximate a log-normal relation with standard deviations between 0.6 and 1.4. The relevant degradation or failure processes have activation energies near 1.0 eV, which give rise to projected median lifetimes at 60°C (channel temperature) over 107 hours and corresponding failure rates (excepting infant mortality) under 40 FITs (40 per 109 device-hours) at 20 years of service.","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1978-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133702201","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 : 1978-07-08DOI: 10.1002/J.1538-7305.1978.TB02154.X
E. Nagelberg, M. Pilla
The paper presents a case history in applying the MERT executive to a large software project based on the UNIX∗ system. The work illustrates some of the basic architectural differences between the MERT and UNIX systems as well as the problems of portability. Emphasis is on matters pertaining to software engineering and administration as they affect development and support of a manufactured product.
{"title":"UNIX time-sharing system: RBCS/RCMAS — converting to the MERT operating system","authors":"E. Nagelberg, M. Pilla","doi":"10.1002/J.1538-7305.1978.TB02154.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1978.TB02154.X","url":null,"abstract":"The paper presents a case history in applying the MERT executive to a large software project based on the UNIX∗ system. The work illustrates some of the basic architectural differences between the MERT and UNIX systems as well as the problems of portability. Emphasis is on matters pertaining to software engineering and administration as they affect development and support of a manufactured product.","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1978-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120291821","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 : 1978-07-08DOI: 10.1002/J.1538-7305.1978.TB02151.X
A. Fraser
The circuit design engineer who wants to obtain rapid prototype construction of one-of-a-kind designs can get help by using programs that run under the UNIX∗ operating system. The programs include means for drawing circuit schematics on a graphics terminal and semi-automatic production of wire lists from those drawings. Included in the package are programs that check for simple errors and an interactive graphics program for performing the physical design of a circuit board. The design aids are oriented toward the production of circuits composed mainly of dual in-line packages mounted on wire-wrap boards. While the graphic editor, called draw, can be used for many purposes, the physical design layout program, called place, is valid only for boards equipped with sockets for dual in-line packages. The programs know how to prepare numerical control information for automatic and semiautomatic wire-wrap machines. The programs use a PDP-11 computer with a Tektronix 4014 graphics terminal attached. Hard copy graphic output is obtainable on some systems from a device attached directly to the terminal; otherwise, the data are transmitted over communications lines to a computing service machine.
{"title":"UNIX time-sharing system: Circuit design aids","authors":"A. Fraser","doi":"10.1002/J.1538-7305.1978.TB02151.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1978.TB02151.X","url":null,"abstract":"The circuit design engineer who wants to obtain rapid prototype construction of one-of-a-kind designs can get help by using programs that run under the UNIX∗ operating system. The programs include means for drawing circuit schematics on a graphics terminal and semi-automatic production of wire lists from those drawings. Included in the package are programs that check for simple errors and an interactive graphics program for performing the physical design of a circuit board. The design aids are oriented toward the production of circuits composed mainly of dual in-line packages mounted on wire-wrap boards. While the graphic editor, called draw, can be used for many purposes, the physical design layout program, called place, is valid only for boards equipped with sockets for dual in-line packages. The programs know how to prepare numerical control information for automatic and semiautomatic wire-wrap machines. The programs use a PDP-11 computer with a Tektronix 4014 graphics terminal attached. Hard copy graphic output is obtainable on some systems from a device attached directly to the terminal; otherwise, the data are transmitted over communications lines to a computing service machine.","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1978-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"118079748","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 : 1978-07-08DOI: 10.1002/J.1538-7305.1978.TB02139.X
S. R. Bourne
The UNIX∗ shell is a command programming language that provides an interface to the UNIX operating system. It contains several mechanisms found in algorithmic languages such as control-flow primitives, variables, and parameter passing. Constructs such as while, if, for, and case are available. Two-way communication is possible between the shell and commands. String-valued parameters, typically file names or flags, may be passed to a command. A return code is set by commands and may be used to determine the flow of control, and the standard output from a command may be used as input to the shell. The shell can modify the environment in which commands run. Input and output can be redirected and processes that communicate through “pipes” can be invoked. Commands are found by searching directories in the file system in a sequence that can be defined by the user.
{"title":"Unix time-sharing system: the unix shell","authors":"S. R. Bourne","doi":"10.1002/J.1538-7305.1978.TB02139.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1978.TB02139.X","url":null,"abstract":"The UNIX∗ shell is a command programming language that provides an interface to the UNIX operating system. It contains several mechanisms found in algorithmic languages such as control-flow primitives, variables, and parameter passing. Constructs such as while, if, for, and case are available. Two-way communication is possible between the shell and commands. String-valued parameters, typically file names or flags, may be passed to a command. A return code is set by commands and may be used to determine the flow of control, and the standard output from a command may be used as input to the shell. The shell can modify the environment in which commands run. Input and output can be redirected and processes that communicate through “pipes” can be invoked. Commands are found by searching directories in the file system in a sequence that can be defined by the user.","PeriodicalId":447574,"journal":{"name":"The Bell System Technical Journal","volume":"100 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1978-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117441892","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：