Pub Date : 1982-10-01DOI: 10.1109/MILCOM.1982.4805978
R. Mathis, K. Kaufman
A new algorithm for adaptively steering antenna pattern nulls while maintaining a pattern maximum on a desired signal is described. The derivation is carried out by maximizing an estimate of the signal-power-to-interference-power ratio. The resulting algorithm employs double loops; one set maximizes the desired signal power and the other set minimizes the interference power. The MAXIMIN algorithm does not require detailed knowledge of the received signal. Rather, it requires only that the desired signal plus interference and noise be separated from interference and noise alone. A detailed simulation of a spread-spectrum (FH/PN) modem incorporating the MAXIMIN algorithm has been developed. The simulation incorporates all known hardware effects having a significant impact on the operation of the algorithm such as: differing group delays of critical filters, nonlinear effects in the cross-correlation multipliers, limited bit resolution in A/D and D/A converters, and mutual coupling between the array elements. Excellent performance in terms of convergence speed and final signal-to-noise ratio is obtained over a wide range of interference conditions. This approach appears to be well suited to frequency-hopping modems.
{"title":"Maximin Adaptive Array Algorithm","authors":"R. Mathis, K. Kaufman","doi":"10.1109/MILCOM.1982.4805978","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4805978","url":null,"abstract":"A new algorithm for adaptively steering antenna pattern nulls while maintaining a pattern maximum on a desired signal is described. The derivation is carried out by maximizing an estimate of the signal-power-to-interference-power ratio. The resulting algorithm employs double loops; one set maximizes the desired signal power and the other set minimizes the interference power. The MAXIMIN algorithm does not require detailed knowledge of the received signal. Rather, it requires only that the desired signal plus interference and noise be separated from interference and noise alone. A detailed simulation of a spread-spectrum (FH/PN) modem incorporating the MAXIMIN algorithm has been developed. The simulation incorporates all known hardware effects having a significant impact on the operation of the algorithm such as: differing group delays of critical filters, nonlinear effects in the cross-correlation multipliers, limited bit resolution in A/D and D/A converters, and mutual coupling between the array elements. Excellent performance in terms of convergence speed and final signal-to-noise ratio is obtained over a wide range of interference conditions. This approach appears to be well suited to frequency-hopping modems.","PeriodicalId":179832,"journal":{"name":"MILCOM 1982 - IEEE Military Communications Conference - Progress in Spread Spectrum Communications","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123167505","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 : 1982-10-01DOI: 10.1109/MILCOM.1982.4806009
P. Major
Measurements have been made of a spread spectrum transmitter as an interference source to conventional receivers. The measurements provide data to permit some validation of models for EMC analysis. This paper discusses one set of results.
{"title":"Spread Spectrum EMC: Measurements and Analysis","authors":"P. Major","doi":"10.1109/MILCOM.1982.4806009","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4806009","url":null,"abstract":"Measurements have been made of a spread spectrum transmitter as an interference source to conventional receivers. The measurements provide data to permit some validation of models for EMC analysis. This paper discusses one set of results.","PeriodicalId":179832,"journal":{"name":"MILCOM 1982 - IEEE Military Communications Conference - Progress in Spread Spectrum Communications","volume":"82 s56","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120854689","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 : 1982-10-01DOI: 10.1109/MILCOM.1982.4806016
F. Bond
The current MILSATCOM assets are reviewed and assessed with regard to the ultimate military potential of the satellite transmission medium. Examples are presented showing why the future use of satellite communication will be impacted by geopolitical trends and re-directions in national policy. The key military issue is surviving and enduring communication over the entire spectrum of conflict levels and the need for a balanced defense against all possible threats. The importance of the network approach involving diverse transmission media is stressed. This in turn requires a more determined effort for achieving improved interoperability with the use of transmission standards. The proposed course for future MILSATCOM systems is based on: evolution toward higher frequencies, internetting of satellite and ground links, ability to reconfigure satcom assets, and more sophisticated access and network control. Also addressed is the suggested policy for exploiting the extensive commercial satcom facilities and the need for closer coordination with the organizations planning the future major terrestrial communication systems.
{"title":"Long Range MILSATCOM Architecture","authors":"F. Bond","doi":"10.1109/MILCOM.1982.4806016","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4806016","url":null,"abstract":"The current MILSATCOM assets are reviewed and assessed with regard to the ultimate military potential of the satellite transmission medium. Examples are presented showing why the future use of satellite communication will be impacted by geopolitical trends and re-directions in national policy. The key military issue is surviving and enduring communication over the entire spectrum of conflict levels and the need for a balanced defense against all possible threats. The importance of the network approach involving diverse transmission media is stressed. This in turn requires a more determined effort for achieving improved interoperability with the use of transmission standards. The proposed course for future MILSATCOM systems is based on: evolution toward higher frequencies, internetting of satellite and ground links, ability to reconfigure satcom assets, and more sophisticated access and network control. Also addressed is the suggested policy for exploiting the extensive commercial satcom facilities and the need for closer coordination with the organizations planning the future major terrestrial communication systems.","PeriodicalId":179832,"journal":{"name":"MILCOM 1982 - IEEE Military Communications Conference - Progress in Spread Spectrum Communications","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127712624","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 : 1982-10-01DOI: 10.1109/MILCOM.1982.4805980
Michael D. Kennedy
While it appears desirable to allow spread spectrum communications in the civilian environment, a number of questions must be answered before its introduction. How will the Commission authorize spread spectrum, with its large radio frequency bandwidth, in a spectrum that has largely been divided into many narrow bands? How can the Commission, with the aid of its licensees, monitor spread spectrum transmissions and enforce both technical and operational regulations? What will be the extent of interference between spread spectrum and narrow band-signals? It appears that these questions can be answered, and the problems they typify mitigated, by careful management on the part of the Commission.
{"title":"Regulatory Aspects of Spread Spectrum Communications","authors":"Michael D. Kennedy","doi":"10.1109/MILCOM.1982.4805980","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4805980","url":null,"abstract":"While it appears desirable to allow spread spectrum communications in the civilian environment, a number of questions must be answered before its introduction. How will the Commission authorize spread spectrum, with its large radio frequency bandwidth, in a spectrum that has largely been divided into many narrow bands? How can the Commission, with the aid of its licensees, monitor spread spectrum transmissions and enforce both technical and operational regulations? What will be the extent of interference between spread spectrum and narrow band-signals? It appears that these questions can be answered, and the problems they typify mitigated, by careful management on the part of the Commission.","PeriodicalId":179832,"journal":{"name":"MILCOM 1982 - IEEE Military Communications Conference - Progress in Spread Spectrum Communications","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128038948","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 : 1982-10-01DOI: 10.1109/MILCOM.1982.4805908
R. McEliece, W. Stark
We take an abstract view of the problem of coding vs. a jammer on a binary symmetric channel, and conclude that either: coding can completely newtralize the jammer, i.e. render him no worse than uniform background noise; or: the best code rate is exactly r = .3790. Here "best" is with respect to channel capacity as a figure of merit. If the channel cutoff rate is used instead, the best rate is .247. We also give some extensions to M-ary channels, M ¿ 2.
{"title":"The Optimal Code Rate vs. a Partial Band Jammer","authors":"R. McEliece, W. Stark","doi":"10.1109/MILCOM.1982.4805908","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4805908","url":null,"abstract":"We take an abstract view of the problem of coding vs. a jammer on a binary symmetric channel, and conclude that either: coding can completely newtralize the jammer, i.e. render him no worse than uniform background noise; or: the best code rate is exactly r = .3790. Here \"best\" is with respect to channel capacity as a figure of merit. If the channel cutoff rate is used instead, the best rate is .247. We also give some extensions to M-ary channels, M ¿ 2.","PeriodicalId":179832,"journal":{"name":"MILCOM 1982 - IEEE Military Communications Conference - Progress in Spread Spectrum Communications","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121289152","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 : 1982-10-01DOI: 10.1109/MILCOM.1982.4805921
M. Beeler
Digital communications on a shared, random access channel benefits from good codes to synchronize and to multiplex the data. Such codes have high autocorrelation and low crosscorrelation, respectively. Finding long binary sequences with these properties is difficult, and generally involves significant brute force searching. A custom computing engine performs such a search much faster than other approaches, and a custom VLSI chip is a practical means of constructing such an engine. The practical advantages and costs of this approach are discussed.
{"title":"Finding Good Signalling Codes with Custom VLSI","authors":"M. Beeler","doi":"10.1109/MILCOM.1982.4805921","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4805921","url":null,"abstract":"Digital communications on a shared, random access channel benefits from good codes to synchronize and to multiplex the data. Such codes have high autocorrelation and low crosscorrelation, respectively. Finding long binary sequences with these properties is difficult, and generally involves significant brute force searching. A custom computing engine performs such a search much faster than other approaches, and a custom VLSI chip is a practical means of constructing such an engine. The practical advantages and costs of this approach are discussed.","PeriodicalId":179832,"journal":{"name":"MILCOM 1982 - IEEE Military Communications Conference - Progress in Spread Spectrum Communications","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122697980","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 : 1982-10-01DOI: 10.1109/MILCOM.1982.4805912
A. Budreau, R. T. Webster
The feasibility of using a surface acoustic wave device with switchable, closely spaced taps as a frequency hopping filter has been demonstrated. The test devices operate at 200-300 MHz for a Texas Instruments lithium niobate wire-bonded filter, (ref. 1) and 125-135 MHz for a United Technologies Research Center monolithic gallium arsenide (GaAs) device. (ref. 2) Future work is planned to develop GaAs monolithic versions at 0.5 and 1.0 GHz. These are, in fact, programmable transversal filters. They perform a variety of time domain functions such as matched filtering (asynchronous correlation), and they operate as variable frequency domain devices as well. In the latter mode, variable width passbands and notch rejection, as well as tunable bandpass, are achievable. Thus, adaptive operation in an electronic warfare scenario is a possible application. A planned use is in the Air Force's Integrated Communications, Navigation, Identification Avionics (ICNIA) program.
{"title":"Frequency-Hopping Filters and Programmable Matched Filters for Spread-Spectrum Systems","authors":"A. Budreau, R. T. Webster","doi":"10.1109/MILCOM.1982.4805912","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4805912","url":null,"abstract":"The feasibility of using a surface acoustic wave device with switchable, closely spaced taps as a frequency hopping filter has been demonstrated. The test devices operate at 200-300 MHz for a Texas Instruments lithium niobate wire-bonded filter, (ref. 1) and 125-135 MHz for a United Technologies Research Center monolithic gallium arsenide (GaAs) device. (ref. 2) Future work is planned to develop GaAs monolithic versions at 0.5 and 1.0 GHz. These are, in fact, programmable transversal filters. They perform a variety of time domain functions such as matched filtering (asynchronous correlation), and they operate as variable frequency domain devices as well. In the latter mode, variable width passbands and notch rejection, as well as tunable bandpass, are achievable. Thus, adaptive operation in an electronic warfare scenario is a possible application. A planned use is in the Air Force's Integrated Communications, Navigation, Identification Avionics (ICNIA) program.","PeriodicalId":179832,"journal":{"name":"MILCOM 1982 - IEEE Military Communications Conference - Progress in Spread Spectrum Communications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130011707","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 : 1982-10-01DOI: 10.1109/MILCOM.1982.4805970
P. Anderson, F. Hsu, M. Sandler
Reliable digital communication over long-haul HF circuits, at rates above 1 bps/Hz, is possible if an adaptive equalizer technique is used which will successfully follow the fading characteristics of the time-dispersive channel. This paper summarizes an investigation of this tracking problem which led to the selection of a square-root Kalman algorithm to update the coefficients of a decision feedback equalizer (DFE). The design and implementation of a new HF modem utilizing the Kalman DFE in conjunction with a continuous GO BACK N ARQ strategy is described. Results of performance tests at data rates from 2400 to 9600 bps using a 3 kHz real-time HF channel simulator are presented. Both low error rate and high throughput are achieved using the combined adaptive channel equalization and ARQ techniques. Preliminary results from tests over a long-haul live link are also reported.
{"title":"A New Adaptive Modem for Long Haul HF Digital Communications at Data Rates Greater than 1 bps/Hz","authors":"P. Anderson, F. Hsu, M. Sandler","doi":"10.1109/MILCOM.1982.4805970","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4805970","url":null,"abstract":"Reliable digital communication over long-haul HF circuits, at rates above 1 bps/Hz, is possible if an adaptive equalizer technique is used which will successfully follow the fading characteristics of the time-dispersive channel. This paper summarizes an investigation of this tracking problem which led to the selection of a square-root Kalman algorithm to update the coefficients of a decision feedback equalizer (DFE). The design and implementation of a new HF modem utilizing the Kalman DFE in conjunction with a continuous GO BACK N ARQ strategy is described. Results of performance tests at data rates from 2400 to 9600 bps using a 3 kHz real-time HF channel simulator are presented. Both low error rate and high throughput are achieved using the combined adaptive channel equalization and ARQ techniques. Preliminary results from tests over a long-haul live link are also reported.","PeriodicalId":179832,"journal":{"name":"MILCOM 1982 - IEEE Military Communications Conference - Progress in Spread Spectrum Communications","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131216257","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 : 1982-10-01DOI: 10.1109/MILCOM.1982.4805937
J. Handwerker
An interactive, real-time Voice System can provide on-line, intelligible, synthetic speech over a 75 bits-per-second (b/s) teletype Air Force Satellite Communications (AFSATCOM) channel. This flexible, cost-effective system operates in both clear and secure AFSATCOM operational modes. The demonstration hardware and software are described along with background information on the AFSArCOM system. The conclusion is that adding voice response to existing hard-copy teletype output over a limited capacity channel is feasible without modifying AFSATCOM hardware or software. In addition, such a Voice System appears attractive for other applications where channel capacity restricts operation to low data rates only.
{"title":"AFSATCOM-Compatible 75 b/s Voice System","authors":"J. Handwerker","doi":"10.1109/MILCOM.1982.4805937","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4805937","url":null,"abstract":"An interactive, real-time Voice System can provide on-line, intelligible, synthetic speech over a 75 bits-per-second (b/s) teletype Air Force Satellite Communications (AFSATCOM) channel. This flexible, cost-effective system operates in both clear and secure AFSATCOM operational modes. The demonstration hardware and software are described along with background information on the AFSArCOM system. The conclusion is that adding voice response to existing hard-copy teletype output over a limited capacity channel is feasible without modifying AFSATCOM hardware or software. In addition, such a Voice System appears attractive for other applications where channel capacity restricts operation to low data rates only.","PeriodicalId":179832,"journal":{"name":"MILCOM 1982 - IEEE Military Communications Conference - Progress in Spread Spectrum Communications","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122364439","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 : 1982-10-01DOI: 10.1109/MILCOM.1982.4806017
R. Varley, J. Conn
The Department of Defense (DOD) MILSATCOM community is rapidly moving toward deployment of Extremely High Frequency (EHF) earth terminals by the late 1980's. As a result, the communications system tradeoffs have solidified into more meaningful terminal specifications, including antenna requirements. Some aspects of antenna requirements at the selected EHF have not been encountered or emphasized in earlier SATCOM applications. It is the objective of this paper to review the system factors of antenna performance and to discuss some of the more pertinent tradeoffs leading to affordable solutions. This paper is aimed at the practicing antenna systems engineer and engineering management personnel of both equipment contractors and procuring agencies. The discussion attempts to distinguish between mobile and fixed platform applications, and concludes with a mobile antenna example at 20/45 gigahertz (GHz) which has been designed, built, and tested.
{"title":"EHF SATCOM Terminal Antennas","authors":"R. Varley, J. Conn","doi":"10.1109/MILCOM.1982.4806017","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4806017","url":null,"abstract":"The Department of Defense (DOD) MILSATCOM community is rapidly moving toward deployment of Extremely High Frequency (EHF) earth terminals by the late 1980's. As a result, the communications system tradeoffs have solidified into more meaningful terminal specifications, including antenna requirements. Some aspects of antenna requirements at the selected EHF have not been encountered or emphasized in earlier SATCOM applications. It is the objective of this paper to review the system factors of antenna performance and to discuss some of the more pertinent tradeoffs leading to affordable solutions. This paper is aimed at the practicing antenna systems engineer and engineering management personnel of both equipment contractors and procuring agencies. The discussion attempts to distinguish between mobile and fixed platform applications, and concludes with a mobile antenna example at 20/45 gigahertz (GHz) which has been designed, built, and tested.","PeriodicalId":179832,"journal":{"name":"MILCOM 1982 - IEEE Military Communications Conference - Progress in Spread Spectrum Communications","volume":"260 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127366578","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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