Pub Date : 1982-10-01DOI: 10.1109/MILCOM.1982.4805974
J. Low, S. Waldstein
The use of spread-spectrum techniques to reduce jamming vulnerability and probability of intercept is fundamental in many military communication systems. This paper describes the design of an experimental spread-spectrum modem (modulator-demodulator) built to interface with an existing HF test facility that offers an equalized 1 MHz bandwidth over skywave paths. The modem uses differential binary and quadrature phase shift keying data modulation and direct-sequence bi-phase spreading techniques. Programmable charge-coupled-device matched filters, which allow symbol-to-symbol code agility, and coherent pre-detection integration provide up to 30 dB of processing gain at a 500 bits/second data rate. Flexible data rate and range (time-of-arrival) tracking to maintain bit synchronization are incorporated into the system.
{"title":"A Direct Sequence Spread-Spectrum Modem for Wideband HF Channels","authors":"J. Low, S. Waldstein","doi":"10.1109/MILCOM.1982.4805974","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4805974","url":null,"abstract":"The use of spread-spectrum techniques to reduce jamming vulnerability and probability of intercept is fundamental in many military communication systems. This paper describes the design of an experimental spread-spectrum modem (modulator-demodulator) built to interface with an existing HF test facility that offers an equalized 1 MHz bandwidth over skywave paths. The modem uses differential binary and quadrature phase shift keying data modulation and direct-sequence bi-phase spreading techniques. Programmable charge-coupled-device matched filters, which allow symbol-to-symbol code agility, and coherent pre-detection integration provide up to 30 dB of processing gain at a 500 bits/second data rate. Flexible data rate and range (time-of-arrival) tracking to maintain bit synchronization are incorporated into the system.","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":"121216389","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.1982.4805940
D. C. Andrews, E. E. Barr, T. E. Olver, B. S. Abrams
To fulfill modern Naval command, control, and communication (C3) requirements a new wideband High Frequency (HF) communications system is being developed that is characterized by the complete removal of high power switching and tuning, and that uses adaptive cancellation techniques in the transmitting subsystem to suppress unwanted radiation of noise and distortion. The paper focuses on the development of an unusually linear 500 watt power amplifier and describes techniques that have been applied to further reduce noise and distortion product generation by means of an iteration of feedforward cancellation stages. Although three stages have been planned, only two have been implemented. To minimize power handling and distortion requirements of the error amplifiers, adaptively controlled weights are used to augment fixed equalizers in the cancellation of fundamental energy for each stage. Performance measurements verifying the concept are presented and various practical limitations are described. Intermodulation distortion to signal ratios of -86 dBc have been achieved.
{"title":"Linear Wideband HF Power Amplifier using Adaptive Feedforward Cancellation","authors":"D. C. Andrews, E. E. Barr, T. E. Olver, B. S. Abrams","doi":"10.1109/MILCOM.1982.4805940","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4805940","url":null,"abstract":"To fulfill modern Naval command, control, and communication (C3) requirements a new wideband High Frequency (HF) communications system is being developed that is characterized by the complete removal of high power switching and tuning, and that uses adaptive cancellation techniques in the transmitting subsystem to suppress unwanted radiation of noise and distortion. The paper focuses on the development of an unusually linear 500 watt power amplifier and describes techniques that have been applied to further reduce noise and distortion product generation by means of an iteration of feedforward cancellation stages. Although three stages have been planned, only two have been implemented. To minimize power handling and distortion requirements of the error amplifiers, adaptively controlled weights are used to augment fixed equalizers in the cancellation of fundamental energy for each stage. Performance measurements verifying the concept are presented and various practical limitations are described. Intermodulation distortion to signal ratios of -86 dBc have been achieved.","PeriodicalId":179832,"journal":{"name":"MILCOM 1982 - IEEE Military Communications Conference - Progress in Spread Spectrum Communications","volume":"31 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":"121261069","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.1982.4805969
H. Kashian, D. C. Rogers, J. Walker
High frequency communication systems have long been in widespread use in military communications. The major limitations of HF have been the frequent outage due to the dynamic characteristics of the ionosphere and the noise generated by other spectrum users and natural sources. Links employing a communication frequency assigned on a fixed schedule based on long-term predictions could expect only about 50 percent availability on the average. Newer HF systems use techniques which sense propagation conditions and adapt to them by automatically selecting a frequency which provides communications. Link availability can be increased to above 90 percent with automatic frequency selection and can be further improved through path diversity which allows the relaying of messages through an alternate set of paths if the direct ionospheric path does not provide adequate propagation. At present no quantitative data exist which allow determination of the communications reliability available to a user over a long period of time as a function of the number and geographic distribution of network members and the number of communication frequencies assigned to them. This paper describes efforts to obtain such data and presents some sample results. Initially a receive-only system was developed from low cost, readily obtainable components. Transmissions of opportunity provided the channel sounding signals, and ionospheric loss data was obtained at a number of frequencies and over a number of diverse paths in near real-time. Experimental results obtained from this system demonstrate a marked reduction in the power required to communicate when frequency and path flexibility exist.
{"title":"Propagation Measurements over Geographically Diverse Paths","authors":"H. Kashian, D. C. Rogers, J. Walker","doi":"10.1109/MILCOM.1982.4805969","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4805969","url":null,"abstract":"High frequency communication systems have long been in widespread use in military communications. The major limitations of HF have been the frequent outage due to the dynamic characteristics of the ionosphere and the noise generated by other spectrum users and natural sources. Links employing a communication frequency assigned on a fixed schedule based on long-term predictions could expect only about 50 percent availability on the average. Newer HF systems use techniques which sense propagation conditions and adapt to them by automatically selecting a frequency which provides communications. Link availability can be increased to above 90 percent with automatic frequency selection and can be further improved through path diversity which allows the relaying of messages through an alternate set of paths if the direct ionospheric path does not provide adequate propagation. At present no quantitative data exist which allow determination of the communications reliability available to a user over a long period of time as a function of the number and geographic distribution of network members and the number of communication frequencies assigned to them. This paper describes efforts to obtain such data and presents some sample results. Initially a receive-only system was developed from low cost, readily obtainable components. Transmissions of opportunity provided the channel sounding signals, and ionospheric loss data was obtained at a number of frequencies and over a number of diverse paths in near real-time. Experimental results obtained from this system demonstrate a marked reduction in the power required to communicate when frequency and path flexibility exist.","PeriodicalId":179832,"journal":{"name":"MILCOM 1982 - IEEE Military Communications Conference - Progress in Spread Spectrum Communications","volume":"77 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":"122487414","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.1982.4805939
R. Dixon
Direct sequence modulated spread spectrum systems are quite similar in many ways to more conventional digital communications systems. They employ some form of phase shift amplitude shift frequency shift keying to modulate their carriers and provide the desired spread bandwidth. A key consideration, however, is the choice of carrier modulation to provide maximum antijamming margin while operating in nonlinear processing, plus minimizing impact on synchronization and cost/complexity of the modulators, demodulators, and synchronizers required. This paper examines the relationships that exist between the various candidate waveforms and shows their common roots. Also defined are the criteria that affect the choice of a waveforms, where various implementations are possible.
{"title":"A Simplified Approach to Direct Sequence Carrier Modulation and its Selection","authors":"R. Dixon","doi":"10.1109/MILCOM.1982.4805939","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4805939","url":null,"abstract":"Direct sequence modulated spread spectrum systems are quite similar in many ways to more conventional digital communications systems. They employ some form of phase shift amplitude shift frequency shift keying to modulate their carriers and provide the desired spread bandwidth. A key consideration, however, is the choice of carrier modulation to provide maximum antijamming margin while operating in nonlinear processing, plus minimizing impact on synchronization and cost/complexity of the modulators, demodulators, and synchronizers required. This paper examines the relationships that exist between the various candidate waveforms and shows their common roots. Also defined are the criteria that affect the choice of a waveforms, where various implementations are possible.","PeriodicalId":179832,"journal":{"name":"MILCOM 1982 - IEEE Military Communications Conference - Progress in Spread Spectrum Communications","volume":"8 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":"128483689","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.1982.4805968
R. Orr
Conventional slow-hopped MFSK communications systems exhibit well-understood susceptibilities to partial-band, pulsed, and repeat-back jamming. Error probability can be degraded to inverse rather than exponential dependence on Eb/No unless appropriate diversity, coding, and interleaving are used. Hopping the FSK tones on independent patterns is known to ameliorate repeat-back jamming. In this paper we look at how a system using all these techniques is able to withstand simultaneous repeat-back and partial-band jamming. The result is that when both communicator and jammer optimize their strategies, the combined jamming is no more effective than either technique used separately, even though the jammer has a spectrum of strategies that all achieve the best result.
{"title":"Performance of MFSK in Simultaneous Partial-Band and Repeat-Back Jamming","authors":"R. Orr","doi":"10.1109/MILCOM.1982.4805968","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4805968","url":null,"abstract":"Conventional slow-hopped MFSK communications systems exhibit well-understood susceptibilities to partial-band, pulsed, and repeat-back jamming. Error probability can be degraded to inverse rather than exponential dependence on Eb/No unless appropriate diversity, coding, and interleaving are used. Hopping the FSK tones on independent patterns is known to ameliorate repeat-back jamming. In this paper we look at how a system using all these techniques is able to withstand simultaneous repeat-back and partial-band jamming. The result is that when both communicator and jammer optimize their strategies, the combined jamming is no more effective than either technique used separately, even though the jammer has a spectrum of strategies that all achieve the best result.","PeriodicalId":179832,"journal":{"name":"MILCOM 1982 - IEEE Military Communications Conference - Progress in Spread Spectrum Communications","volume":"3 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":"125298153","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.1982.4805988
T. Healy
Spread spectrum communication systems offer a number of advantages in multiple access situations, compared with alternative approaches. A major disadvantage of spread spectrum is the low spectral efficiency due to mutual interference from other users of the system. In theory channel coding can increase this efficiency to about 70% for asynchronous systems, and 100% for synchronous systems. The channel capacity, and hence the spectral efficiency, is obtained here for the general case of a synchronous OR channel supporting n users with different data rates. The form of the results shows clearly how the interference from one user can be traded for that of another. Some alternative models are also investigated, primarily to show the effect of changes in the model on the capacity region.
{"title":"The Capacity Region of a Spread Spectrum Multiple-Access Channel","authors":"T. Healy","doi":"10.1109/MILCOM.1982.4805988","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4805988","url":null,"abstract":"Spread spectrum communication systems offer a number of advantages in multiple access situations, compared with alternative approaches. A major disadvantage of spread spectrum is the low spectral efficiency due to mutual interference from other users of the system. In theory channel coding can increase this efficiency to about 70% for asynchronous systems, and 100% for synchronous systems. The channel capacity, and hence the spectral efficiency, is obtained here for the general case of a synchronous OR channel supporting n users with different data rates. The form of the results shows clearly how the interference from one user can be traded for that of another. Some alternative models are also investigated, primarily to show the effect of changes in the model on the capacity region.","PeriodicalId":179832,"journal":{"name":"MILCOM 1982 - IEEE Military Communications Conference - Progress in Spread Spectrum Communications","volume":"61 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":"121481421","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.1982.4805947
David J. Balicki
The purpose of the Cable Data Network for the MX-Missile System is to provide secure, reliable, pre-attack data communications for the MX-Wing using a fiber optic cable network. Various network architectures were considered; of these, only four designs met all the system requirements. This paper discusses the studies undertaken to determine the network design which performed best in terms of preservation of location uncertainty, operational simplicity, cost-effectiveness and performance. A computerized simulation of the data communications flow within the MX-Wing was also undertaken, and it provided network performance predictions which aided in the decision to adopt one particular network design as the best alternative to implement the cable data network.
{"title":"Cable Data Network for the MX-Missile System","authors":"David J. Balicki","doi":"10.1109/MILCOM.1982.4805947","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4805947","url":null,"abstract":"The purpose of the Cable Data Network for the MX-Missile System is to provide secure, reliable, pre-attack data communications for the MX-Wing using a fiber optic cable network. Various network architectures were considered; of these, only four designs met all the system requirements. This paper discusses the studies undertaken to determine the network design which performed best in terms of preservation of location uncertainty, operational simplicity, cost-effectiveness and performance. A computerized simulation of the data communications flow within the MX-Wing was also undertaken, and it provided network performance predictions which aided in the decision to adopt one particular network design as the best alternative to implement the cable data network.","PeriodicalId":179832,"journal":{"name":"MILCOM 1982 - IEEE Military Communications Conference - Progress in Spread Spectrum Communications","volume":"37 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":"123072345","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.1982.4805915
T. Huang, L. Yen
The error probability of a noncoherent MFSK/FH receiver in the presence of interference and thermal Gaussian noise is presented. The interference is assumed to be either partial-band or full-band noise-like or CW (Continuous-Wave) tones, and it hits randomly a fixed number of matched filter channels of the receiver. An expression for error probability for the noise-like interference is obtained; that for CW interference involves some untractable integrals which are evaluated by numerical schemes, called modified Hermite Gaussian quadrature formulas. It is found that the schemes are not only highly effective but also accurate. Numerical examples for error probabilities and receiver degradation are given as a function of interference-to-signal power and signal-to-noise spectral density (Eb/No) ratios.
{"title":"Error Probability of a Noncoherent MFSK/FH Receiver in the Presence of Interference and Gaussian Noise","authors":"T. Huang, L. Yen","doi":"10.1109/MILCOM.1982.4805915","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4805915","url":null,"abstract":"The error probability of a noncoherent MFSK/FH receiver in the presence of interference and thermal Gaussian noise is presented. The interference is assumed to be either partial-band or full-band noise-like or CW (Continuous-Wave) tones, and it hits randomly a fixed number of matched filter channels of the receiver. An expression for error probability for the noise-like interference is obtained; that for CW interference involves some untractable integrals which are evaluated by numerical schemes, called modified Hermite Gaussian quadrature formulas. It is found that the schemes are not only highly effective but also accurate. Numerical examples for error probabilities and receiver degradation are given as a function of interference-to-signal power and signal-to-noise spectral density (Eb/No) ratios.","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":"130280897","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.1982.4805919
P. Stynes, John Lovell, H. Sunkenberg, A. Giordano
This paper describes performance and implementation considerations for waveforms applicable to a spread spectrum radio network operating under a simulcast discipline. Performance data is obtained through Monte Carlo simulation of the receiver. Implementation data is presented in terms of component counts and power estimates for the digital portions of the receivers.
{"title":"Waveform Alternatives for a Frequency-Hopped Simulcast Radio Network","authors":"P. Stynes, John Lovell, H. Sunkenberg, A. Giordano","doi":"10.1109/MILCOM.1982.4805919","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4805919","url":null,"abstract":"This paper describes performance and implementation considerations for waveforms applicable to a spread spectrum radio network operating under a simulcast discipline. Performance data is obtained through Monte Carlo simulation of the receiver. Implementation data is presented in terms of component counts and power estimates for the digital portions of the receivers.","PeriodicalId":179832,"journal":{"name":"MILCOM 1982 - IEEE Military Communications Conference - Progress in Spread Spectrum Communications","volume":"41 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":"124616399","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.1982.4805928
K. Chung, O. Mowafi, K. Sohraby
WWMCCS Intercomputer Network (WIN) is an ARPANET based packet switched network. It provides the backbone service between a large number of WWMCCS hosts. The Performance Optimization Research Model (PERFORM) has been developed and is used as an engineering aid for capacity planning and performance management in the WWMCCS environment. PERFORM consists of an integrated set of queueing theoretic models for both the WWMCCS hosts and the WIN subsystems. PERFORM is hybrid in nature with some analytic models used to compute parameter values for an event-driven simulator. This paper will present the mathematical details and corresponding analysis of PERFORM.
wwmcs计算机间网络(WIN)是基于ARPANET的分组交换网络。它提供了大量wwmcs主机之间的骨干服务。性能优化研究模型(Performance Optimization Research Model, PERFORM)已经被开发出来，并被用作WWMCCS环境中容量规划和性能管理的工程辅助工具。PERFORM由wwmcs主机和WIN子系统的一套完整的排队理论模型组成。PERFORM本质上是混合了一些用于计算事件驱动模拟器参数值的分析模型。本文将介绍PERFORM的数学细节和相应的分析。
{"title":"Performance Modeling of WWMCCS Intercomputer Network","authors":"K. Chung, O. Mowafi, K. Sohraby","doi":"10.1109/MILCOM.1982.4805928","DOIUrl":"https://doi.org/10.1109/MILCOM.1982.4805928","url":null,"abstract":"WWMCCS Intercomputer Network (WIN) is an ARPANET based packet switched network. It provides the backbone service between a large number of WWMCCS hosts. The Performance Optimization Research Model (PERFORM) has been developed and is used as an engineering aid for capacity planning and performance management in the WWMCCS environment. PERFORM consists of an integrated set of queueing theoretic models for both the WWMCCS hosts and the WIN subsystems. PERFORM is hybrid in nature with some analytic models used to compute parameter values for an event-driven simulator. This paper will present the mathematical details and corresponding analysis of PERFORM.","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":"120991340","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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