Pub Date : 1973-05-06DOI: 10.1002/J.1538-7305.1973.TB01981.X
S. Rice
The bandwidth required to transmit an FM wave is related to how much distortion is allowed in the signal. Here expressions are developed for the distortion (interchannel interference) produced when an FDM-FM wave passes through an ideal filter. The signal is represented by a flat (PM) band of Gaussian noise. The formulas obtained hold only for small rms frequency deviation, but fortunately this is an important case in microwave communication systems. The theoretical expressions agree well with Monte Carlo results published recently by Anuff and Liou.
{"title":"Distortion produced by band limitation of an FM wave","authors":"S. Rice","doi":"10.1002/J.1538-7305.1973.TB01981.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01981.X","url":null,"abstract":"The bandwidth required to transmit an FM wave is related to how much distortion is allowed in the signal. Here expressions are developed for the distortion (interchannel interference) produced when an FDM-FM wave passes through an ideal filter. The signal is represented by a flat (PM) band of Gaussian noise. The formulas obtained hold only for small rms frequency deviation, but fortunately this is an important case in microwave communication systems. The theoretical expressions agree well with Monte Carlo results published recently by Anuff and Liou.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"8 1","pages":"605-626"},"PeriodicalIF":0.0,"publicationDate":"1973-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80769722","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 : 1973-05-06DOI: 10.1002/J.1538-7305.1973.TB01983.X
Joel Goldman
This paper studies a general description of interchannel and intra-channel crosstalk interference created in a communications system. This description is in the form of a Volterra series expansion of the interference signal in terms of the signal which produced the interference. From it we are able to precisely define the “intelligible” part of the crosstalk. This description also provides us with quantitative measures of the amount of crosstalk created in some communications channel by signals in another channel, as well as a measure (intelligible crosstalk ratio) of the amount of intelligible crosstalk produced. We then consider a particular model for the generation of intelligible crosstalk [or direct adjacent channel interference (DACI)] between two neighboring angle-modulated channels in which the signal in one channel adds to the signal of the second channel, the sum is filtered, and the filter output then passes through an AM-PM conversion device. Using our definition, a simple expression for the intelligible crosstalk ratio for this model is derived in terms of the filter characteristic. We observe that this crosstalk ratio exhibits a number of properties usually associated with DACI.
{"title":"A volterra series description of crosstalk interference in communications systems","authors":"Joel Goldman","doi":"10.1002/J.1538-7305.1973.TB01983.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01983.X","url":null,"abstract":"This paper studies a general description of interchannel and intra-channel crosstalk interference created in a communications system. This description is in the form of a Volterra series expansion of the interference signal in terms of the signal which produced the interference. From it we are able to precisely define the “intelligible” part of the crosstalk. This description also provides us with quantitative measures of the amount of crosstalk created in some communications channel by signals in another channel, as well as a measure (intelligible crosstalk ratio) of the amount of intelligible crosstalk produced. We then consider a particular model for the generation of intelligible crosstalk [or direct adjacent channel interference (DACI)] between two neighboring angle-modulated channels in which the signal in one channel adds to the signal of the second channel, the sum is filtered, and the filter output then passes through an AM-PM conversion device. Using our definition, a simple expression for the intelligible crosstalk ratio for this model is derived in terms of the filter characteristic. We observe that this crosstalk ratio exhibits a number of properties usually associated with DACI.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"6 1","pages":"649-668"},"PeriodicalIF":0.0,"publicationDate":"1973-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86877816","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 : 1973-03-01DOI: 10.1002/J.1538-7305.1973.TB01970.X
D. Marcuse, W. Mammel
The dielectric optical waveguide described in this paper has an annular cross section, the refractive index of which is higher than the indices of the material inside and outside of the ring. The solution of the eigenvalue problem is an approximation which is valid for small refractive index differences of the three media. The resulting approximate eigenvalue equation is far simpler than its exact counterpart. The cutoff conditions of the first three modes and the eigenvalue of the lowest-order mode are presented graphically.
{"title":"Tube waveguide for optical transmission","authors":"D. Marcuse, W. Mammel","doi":"10.1002/J.1538-7305.1973.TB01970.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01970.X","url":null,"abstract":"The dielectric optical waveguide described in this paper has an annular cross section, the refractive index of which is higher than the indices of the material inside and outside of the ring. The solution of the eigenvalue problem is an approximation which is valid for small refractive index differences of the three media. The resulting approximate eigenvalue equation is far simpler than its exact counterpart. The cutoff conditions of the first three modes and the eigenvalue of the lowest-order mode are presented graphically.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"61 1","pages":"423-435"},"PeriodicalIF":0.0,"publicationDate":"1973-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86604205","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 : 1973-03-01DOI: 10.1002/J.1538-7305.1973.TB01968.X
D. Chan, L. Rabiner
Experimental results on roundoff noise in cascade realizations of Finite Impulse Response (FIR) digital filters are presented in this paper.∗ The entire roundoff noise distribution (i.e., over all possible orderings) is given for several low-order filters using both sum and peak scaling. Based on observations about this distribution, as well as intuitive arguments about the effects of ordering on roundoff noise, an algorithm for minimizing roundoff noise is presented. Experimental verification of this algorithm for a wide range of filters is given.
{"title":"An algorithm for minimizing roundoff noise in cascade realizations of finite impulse response digital filters","authors":"D. Chan, L. Rabiner","doi":"10.1002/J.1538-7305.1973.TB01968.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01968.X","url":null,"abstract":"Experimental results on roundoff noise in cascade realizations of Finite Impulse Response (FIR) digital filters are presented in this paper.∗ The entire roundoff noise distribution (i.e., over all possible orderings) is given for several low-order filters using both sum and peak scaling. Based on observations about this distribution, as well as intuitive arguments about the effects of ordering on roundoff noise, an algorithm for minimizing roundoff noise is presented. Experimental verification of this algorithm for a wide range of filters is given.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"31 1","pages":"347-385"},"PeriodicalIF":0.0,"publicationDate":"1973-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73455638","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 : 1973-03-01DOI: 10.1002/J.1538-7305.1973.TB01964.X
C. Brackett
IMPATT diode microwave oscillators suffer from the effects of low-frequency instabilities, which include excessive up-conversion of bias-circuit noise, bias-circuit oscillations, and diode burnout induced by tuning at the microwave frequency. These instabilities are particularly troublesome in GaAs diodes, although also present in both Ge and Si to a lesser extent. Moreover, these instabilities are more prominent in higher efficiency, higher power diodes, presenting a severe systems problem in the practical utilization of GaAs diodes at their highest power and efficiency levels. In this paper, it is shown that these instabilities may be eliminated in a systematic and well controlled manner with little or no loss in microwave power or efficiency. It is shown that the source of the unstable behavior is a low-frequency RF voltage-induced negative resistance which extends from dc to several tens, and perhaps hundreds, of megahertz, depending on the loaded Q of the microwave circuit. The negative resistance is an unavoidable fact of large-signal avalanche diode operation and is due to the rectification properties of the nonlinear microwave avalanche.
{"title":"The elimination of tuning-induced burnout and bias-circuit oscillations in IMPATT oscillators","authors":"C. Brackett","doi":"10.1002/J.1538-7305.1973.TB01964.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01964.X","url":null,"abstract":"IMPATT diode microwave oscillators suffer from the effects of low-frequency instabilities, which include excessive up-conversion of bias-circuit noise, bias-circuit oscillations, and diode burnout induced by tuning at the microwave frequency. These instabilities are particularly troublesome in GaAs diodes, although also present in both Ge and Si to a lesser extent. Moreover, these instabilities are more prominent in higher efficiency, higher power diodes, presenting a severe systems problem in the practical utilization of GaAs diodes at their highest power and efficiency levels. In this paper, it is shown that these instabilities may be eliminated in a systematic and well controlled manner with little or no loss in microwave power or efficiency. It is shown that the source of the unstable behavior is a low-frequency RF voltage-induced negative resistance which extends from dc to several tens, and perhaps hundreds, of megahertz, depending on the loaded Q of the microwave circuit. The negative resistance is an unavoidable fact of large-signal avalanche diode operation and is due to the rectification properties of the nonlinear microwave avalanche.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"30 1","pages":"271-306"},"PeriodicalIF":0.0,"publicationDate":"1973-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90260660","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 : 1973-03-01DOI: 10.1002/J.1538-7305.1973.TB01969.X
L. Greenstein
This paper derives a slope overload noise power formula for linear delta modulators having ideal integrators and Gaussian random inputs. Although the same problem has been treated by others, the present result is the only one applicable to all slope-following capacities and input spectra. Despite its singleness of purpose, the paper divides logically into two parts. In Part 1, a common element in all previously published results is used to derive a new slope overload noise power formula. This derivation is analytically rigorous and provides some useful insights, but pertains to a particular kind of spectrum and so is incomplete. The more universal result we seek is derived in Part 2. The approach here is far less rigorous and amounts to approximating the influences of other kinds of spectra by modifying the result of Part 1. The final expression contains four spectrum-related coefficients, for which simple formulas are given, and has an estimated accuracy of 1 dB for all cases of practical interest. Computed results are given for two important families of spectra and comparisons are made with previously published results.
{"title":"Slope overload noise in linear delta modulators with Gaussian inputs","authors":"L. Greenstein","doi":"10.1002/J.1538-7305.1973.TB01969.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01969.X","url":null,"abstract":"This paper derives a slope overload noise power formula for linear delta modulators having ideal integrators and Gaussian random inputs. Although the same problem has been treated by others, the present result is the only one applicable to all slope-following capacities and input spectra. Despite its singleness of purpose, the paper divides logically into two parts. In Part 1, a common element in all previously published results is used to derive a new slope overload noise power formula. This derivation is analytically rigorous and provides some useful insights, but pertains to a particular kind of spectrum and so is incomplete. The more universal result we seek is derived in Part 2. The approach here is far less rigorous and amounts to approximating the influences of other kinds of spectra by modifying the result of Part 1. The final expression contains four spectrum-related coefficients, for which simple formulas are given, and has an estimated accuracy of 1 dB for all cases of practical interest. Computed results are given for two important families of spectra and comparisons are made with previously published results.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"39 1","pages":"387-421"},"PeriodicalIF":0.0,"publicationDate":"1973-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78743093","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 : 1973-03-01DOI: 10.1002/J.1538-7305.1973.TB01971.X
A. Kuczura
Traffic overflowing a first-choice trunk group can be approximated accurately by a simple renewal process called an interrupted Poisson process–a Poisson process which is alternately turned on for an exponentially distributed time and then turned off for another (independent) exponentially distributed time. The approximation is obtained by matching either the first two or three moments of an interrupted Poisson process to those of an overflow process. Numerical investigation of errors in the approximation and subsequent experience has shown that this method of generating overflow traffic is accurate and very useful in both simulations and analyses of traffic systems.
{"title":"The interrupted poisson process as an overflow process","authors":"A. Kuczura","doi":"10.1002/J.1538-7305.1973.TB01971.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01971.X","url":null,"abstract":"Traffic overflowing a first-choice trunk group can be approximated accurately by a simple renewal process called an interrupted Poisson process–a Poisson process which is alternately turned on for an exponentially distributed time and then turned off for another (independent) exponentially distributed time. The approximation is obtained by matching either the first two or three moments of an interrupted Poisson process to those of an overflow process. Numerical investigation of errors in the approximation and subsequent experience has shown that this method of generating overflow traffic is accurate and very useful in both simulations and analyses of traffic systems.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"26 1","pages":"437-448"},"PeriodicalIF":0.0,"publicationDate":"1973-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77253683","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 : 1973-03-01DOI: 10.1002/J.1538-7305.1973.TB01967.X
D. Chan, L. Rabiner
This paper presents a theoretical treatment of the roundoff noise problem for the special case of cascade realizations of Finite Impulse Response (FIR) digital filters.† Explicit relations for evaluating roundoff noise with the usual assumption of uncorrelated samples are presented. Useful scaling methods are stated and classified as to conditions when these methods are optimum. Important differences between use of these scaling procedures for Infinite Impulse Response (IIR) filters and FIR filters are pointed out. Finally, useful properties of linear phase FIR filters are discussed.
{"title":"Theory of roundoff noise in cascade realizations of finite impulse response digital filters","authors":"D. Chan, L. Rabiner","doi":"10.1002/J.1538-7305.1973.TB01967.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01967.X","url":null,"abstract":"This paper presents a theoretical treatment of the roundoff noise problem for the special case of cascade realizations of Finite Impulse Response (FIR) digital filters.† Explicit relations for evaluating roundoff noise with the usual assumption of uncorrelated samples are presented. Useful scaling methods are stated and classified as to conditions when these methods are optimum. Important differences between use of these scaling procedures for Infinite Impulse Response (IIR) filters and FIR filters are pointed out. Finally, useful properties of linear phase FIR filters are discussed.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"167 1","pages":"329-345"},"PeriodicalIF":0.0,"publicationDate":"1973-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75980283","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 : 1973-02-01DOI: 10.1002/J.1538-7305.1973.TB01963.X
P. Kaiser, E. Marcatili, S. Miller
Currently there is strong interest in optical fibers for use as a transmission medium, analogous to the use of coaxial or wire pairs in the low-frequency region. Most work is devoted to a fiber structure consisting of a central glass core surrounded by a cylindrical glass cladding having a slightly lower index of refraction. This in turn requires that the chemical composition of the core glass differs from that of the cladding glass, leading to undesired effects at the core-cladding interface and perhaps limiting the minimum fiber losses achievable.
{"title":"B.S.T.J. brief: A new optical fiber","authors":"P. Kaiser, E. Marcatili, S. Miller","doi":"10.1002/J.1538-7305.1973.TB01963.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01963.X","url":null,"abstract":"Currently there is strong interest in optical fibers for use as a transmission medium, analogous to the use of coaxial or wire pairs in the low-frequency region. Most work is devoted to a fiber structure consisting of a central glass core surrounded by a cylindrical glass cladding having a slightly lower index of refraction. This in turn requires that the chemical composition of the core glass differs from that of the cladding glass, leading to undesired effects at the core-cladding interface and perhaps limiting the minimum fiber losses achievable.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"140 1","pages":"265-269"},"PeriodicalIF":0.0,"publicationDate":"1973-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91325985","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 : 1973-02-01DOI: 10.1002/J.1538-7305.1973.TB01961.X
G. Babler
The spectral characteristics of nondiversity and space diversity narrowband radio channels subject to multipath fading were estimated from a detailed sampling of channel loss variations as measured on two vertically separated antennas. The data base for this analysis was obtained during a 93-day experiment in which the amplitudes of a set of coherent tones spanning a band of 33.55 MHz and centered at 6034.2 MHz were continuously monitored. The most significant observations were: (i) For the nondiversity channel, the frequency selectivity of the received transmission loss generally exceeded linear and quadratic components (in frequency) of amplitude distortion for fade depths greater than 30 dB. (ii) For the diversity channel constructed by switching between a pair of narrowband channels received on two vertically spaced antennas, the frequency selectivity of the transmission loss was significantly reduced.
{"title":"Selectively faded nondiversity and space diversity narrowband microwave Radio channels","authors":"G. Babler","doi":"10.1002/J.1538-7305.1973.TB01961.X","DOIUrl":"https://doi.org/10.1002/J.1538-7305.1973.TB01961.X","url":null,"abstract":"The spectral characteristics of nondiversity and space diversity narrowband radio channels subject to multipath fading were estimated from a detailed sampling of channel loss variations as measured on two vertically separated antennas. The data base for this analysis was obtained during a 93-day experiment in which the amplitudes of a set of coherent tones spanning a band of 33.55 MHz and centered at 6034.2 MHz were continuously monitored. The most significant observations were: (i) For the nondiversity channel, the frequency selectivity of the received transmission loss generally exceeded linear and quadratic components (in frequency) of amplitude distortion for fade depths greater than 30 dB. (ii) For the diversity channel constructed by switching between a pair of narrowband channels received on two vertically spaced antennas, the frequency selectivity of the transmission loss was significantly reduced.","PeriodicalId":55391,"journal":{"name":"Bell System Technical Journal","volume":"13 1","pages":"239-261"},"PeriodicalIF":0.0,"publicationDate":"1973-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89026643","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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