Pub Date : 1989-04-11DOI: 10.1109/MELCON.1989.50062
R. Agustí, J. Olmos
A control scheme suitable for setting the false alarm rate to a fixed value in frequency hopping spread spectrum communications is proposed. the scheme performance is determined in the presence of partial band interference. For this purpose, both analytical and computer simulation techniques have been used, with good agreement in the results obtained.<>
{"title":"Constant false alarm rate control for frequency hopping spread spectrum systems","authors":"R. Agustí, J. Olmos","doi":"10.1109/MELCON.1989.50062","DOIUrl":"https://doi.org/10.1109/MELCON.1989.50062","url":null,"abstract":"A control scheme suitable for setting the false alarm rate to a fixed value in frequency hopping spread spectrum communications is proposed. the scheme performance is determined in the presence of partial band interference. For this purpose, both analytical and computer simulation techniques have been used, with good agreement in the results obtained.<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115786503","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 : 1989-04-11DOI: 10.1109/MELCON.1989.50021
I. Trancoso, L. Almeida, J. Marques, J. Rodrigues
The authors present the results of a feasibility study comparing two basic classes of coders in the mid-rate range (6-8 kbps): CELP and sinusoid based coders. It is concluded that CELP coding is a mature technique able to yield high-quality synthetic speech with some background noise at the mid-rate range. It has a tractable computational complexity and good robustness, making it the best present candidate. Postprocessing can enhance its output quality, though further research is needed in this field. Sinusoidal coding, together with the use of narrowband basis functions, can produce synthetic speech of higher quality than that produced by CELP. Its robustness however, must be increased. This work suggests that a significant research effort into this technique is fully justified.<>
{"title":"High quality mid-rate speech coding","authors":"I. Trancoso, L. Almeida, J. Marques, J. Rodrigues","doi":"10.1109/MELCON.1989.50021","DOIUrl":"https://doi.org/10.1109/MELCON.1989.50021","url":null,"abstract":"The authors present the results of a feasibility study comparing two basic classes of coders in the mid-rate range (6-8 kbps): CELP and sinusoid based coders. It is concluded that CELP coding is a mature technique able to yield high-quality synthetic speech with some background noise at the mid-rate range. It has a tractable computational complexity and good robustness, making it the best present candidate. Postprocessing can enhance its output quality, though further research is needed in this field. Sinusoidal coding, together with the use of narrowband basis functions, can produce synthetic speech of higher quality than that produced by CELP. Its robustness however, must be increased. This work suggests that a significant research effort into this technique is fully justified.<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132223836","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 : 1989-04-11DOI: 10.1109/MELCON.1989.50087
Z. Petrovíc, D. Cuberovic
The authors consider the estimation of symbol error rate (SER) for digital signals transmitted through a satellite channel with a memoryless bandpass nonlinearity, typically an on-board TWT (traveling-wavetube) amplifier in a satellite repeater, when the noise at the input of a nonlinear element is nonnegligible. An improved method of importance sampling is used for SER estimation in a simulation model of a nonlinear satellite channel. The characteristics of the simulation model are as follows: the modulation can generate an MPSK or MQAM signal; at the inputs of the transponder and the receiver Butterworth or Gauss filters are used; the receiver utilizes a device for optimum phase shift of the carrier; and signal sampling is performed at the optimal moment during the signaling period. This model is also used for the analysis of the influence of other system parameters (e.g. filter type, kind of modulation, and backoff) on the quality of signal transmission. Simulation results are presented.<>
{"title":"Application of efficient importance sampling method to the simulation of digital satellite links","authors":"Z. Petrovíc, D. Cuberovic","doi":"10.1109/MELCON.1989.50087","DOIUrl":"https://doi.org/10.1109/MELCON.1989.50087","url":null,"abstract":"The authors consider the estimation of symbol error rate (SER) for digital signals transmitted through a satellite channel with a memoryless bandpass nonlinearity, typically an on-board TWT (traveling-wavetube) amplifier in a satellite repeater, when the noise at the input of a nonlinear element is nonnegligible. An improved method of importance sampling is used for SER estimation in a simulation model of a nonlinear satellite channel. The characteristics of the simulation model are as follows: the modulation can generate an MPSK or MQAM signal; at the inputs of the transponder and the receiver Butterworth or Gauss filters are used; the receiver utilizes a device for optimum phase shift of the carrier; and signal sampling is performed at the optimal moment during the signaling period. This model is also used for the analysis of the influence of other system parameters (e.g. filter type, kind of modulation, and backoff) on the quality of signal transmission. Simulation results are presented.<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134581440","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 : 1989-04-11DOI: 10.1109/MELCON.1989.50167
E. Artal, J. Bará, J. Berenguer, A. Comerón, I. Corbella, L. Pradell
The authors present the 20/30-GHz front-end of the TMS-7 station for performing the measurement of the flux density of one or more signal carriers received from the OLYMPUS satellite. The front-end is composed of two receiving channels and a pilot generator. Local oscillators follow the frequency drifts of the satellite signals using a complex phase-locking system.<>
{"title":"20/30 GHz front-end for the TMS-7 receiving station of the OLYMPUS satellite","authors":"E. Artal, J. Bará, J. Berenguer, A. Comerón, I. Corbella, L. Pradell","doi":"10.1109/MELCON.1989.50167","DOIUrl":"https://doi.org/10.1109/MELCON.1989.50167","url":null,"abstract":"The authors present the 20/30-GHz front-end of the TMS-7 station for performing the measurement of the flux density of one or more signal carriers received from the OLYMPUS satellite. The front-end is composed of two receiving channels and a pilot generator. Local oscillators follow the frequency drifts of the satellite signals using a complex phase-locking system.<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132807316","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 : 1989-04-11DOI: 10.1109/MELCON.1989.50117
B. Pehani
The author analyzes the essential characteristics of different transmission forms of the same message. Attention is given to the characteristics of speech-formed and text-formed information transmission. It is noted that the comparison of these characteristics can help the user in decision making. It is concluded that the proposed approach to this topic can contribute to a better solution of telecommunication problems, particularly in the ISDN (integrated services digital network).<>
{"title":"About dismatch of various digital transmissions at information exchange","authors":"B. Pehani","doi":"10.1109/MELCON.1989.50117","DOIUrl":"https://doi.org/10.1109/MELCON.1989.50117","url":null,"abstract":"The author analyzes the essential characteristics of different transmission forms of the same message. Attention is given to the characteristics of speech-formed and text-formed information transmission. It is noted that the comparison of these characteristics can help the user in decision making. It is concluded that the proposed approach to this topic can contribute to a better solution of telecommunication problems, particularly in the ISDN (integrated services digital network).<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"328 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125213997","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 : 1989-04-11DOI: 10.1109/MELCON.1989.50068
J. Sánchez
The general and package characteristics of a private accounting system for the X.25 host are described. The objective is to record the contribution of each user in the final bill with TELEFONICA SA, Spain's PTT. As the LAN has several hosts with distant operating systems which have access to the X.25 net, the decision was made to build software thinking into the operating system; in this way this software will be useful independently of its installation in a LAN or in an isolated host. The task of this software is not to analyze statistically the use of the X.25 facilities by the users of the LAN, but to do it as a function of the prices of the PTT.<>
{"title":"Private accounting system for X.25 host","authors":"J. Sánchez","doi":"10.1109/MELCON.1989.50068","DOIUrl":"https://doi.org/10.1109/MELCON.1989.50068","url":null,"abstract":"The general and package characteristics of a private accounting system for the X.25 host are described. The objective is to record the contribution of each user in the final bill with TELEFONICA SA, Spain's PTT. As the LAN has several hosts with distant operating systems which have access to the X.25 net, the decision was made to build software thinking into the operating system; in this way this software will be useful independently of its installation in a LAN or in an isolated host. The task of this software is not to analyze statistically the use of the X.25 facilities by the users of the LAN, but to do it as a function of the prices of the PTT.<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133372496","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 : 1989-04-11DOI: 10.1109/MELCON.1989.50075
M. Abu-Regheff, A. Al-Bayati, A.A.M. Al-Jiboury
A novel FH/MFSK (frequency-hopping/M-ary frequency shift keying) receiver is proposed to operate under conditions of stationary multitone jamming. The principle of operation of this receiver relies on power measurements at all of the M-frequencies for each M-ary band before the signal is received in it. The performance of the receiver is evaluated by analytical methods using results obtained by computer simulation. Two cases of multitone jamming were studied, single tone and double tone per M-ary band. These cases represent the worst case of multitone jamming. The proposed receiver outperforms the conventional receiver under these jamming conditions.<>
{"title":"A new FH/MFSK receiver for stationary multitone jamming","authors":"M. Abu-Regheff, A. Al-Bayati, A.A.M. Al-Jiboury","doi":"10.1109/MELCON.1989.50075","DOIUrl":"https://doi.org/10.1109/MELCON.1989.50075","url":null,"abstract":"A novel FH/MFSK (frequency-hopping/M-ary frequency shift keying) receiver is proposed to operate under conditions of stationary multitone jamming. The principle of operation of this receiver relies on power measurements at all of the M-frequencies for each M-ary band before the signal is received in it. The performance of the receiver is evaluated by analytical methods using results obtained by computer simulation. Two cases of multitone jamming were studied, single tone and double tone per M-ary band. These cases represent the worst case of multitone jamming. The proposed receiver outperforms the conventional receiver under these jamming conditions.<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133573111","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 : 1989-04-11DOI: 10.1109/MELCON.1989.50005
M. Akherraz, M. El-Sharkawi
A novel application of quadratic tracking techniques to speed and rotor position control of induction motor drives is introduced. These methods can adaptively adjust the motor speed and/or current to follow certain desired tracks. The tracking performances of the induction machine with these control methods are illustrated through a variety of computer simulations. It is shown that the suboptimal tracking is only effective if the track time constant is much smaller than the final time used to compute the driving vector. An improvement of the suboptimal linear quadratic tracking method is proposed to eliminate this limitation. The test results indicate that the speed of the motor follows the desired track with more than 98% accuracy throughout the tracking time. It is noted that the proposed control method should enhance the use of induction motors in position control applications such as robotics, manipulation, and actuation.<>
{"title":"Tracking techniques for rotor position control of induction motors","authors":"M. Akherraz, M. El-Sharkawi","doi":"10.1109/MELCON.1989.50005","DOIUrl":"https://doi.org/10.1109/MELCON.1989.50005","url":null,"abstract":"A novel application of quadratic tracking techniques to speed and rotor position control of induction motor drives is introduced. These methods can adaptively adjust the motor speed and/or current to follow certain desired tracks. The tracking performances of the induction machine with these control methods are illustrated through a variety of computer simulations. It is shown that the suboptimal tracking is only effective if the track time constant is much smaller than the final time used to compute the driving vector. An improvement of the suboptimal linear quadratic tracking method is proposed to eliminate this limitation. The test results indicate that the speed of the motor follows the desired track with more than 98% accuracy throughout the tracking time. It is noted that the proposed control method should enhance the use of induction motors in position control applications such as robotics, manipulation, and actuation.<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115698625","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 : 1989-04-11DOI: 10.1109/MELCON.1989.49974
C.A. Kagarakis, J. Avaritsiotis
The authors outline some of the main problems of design and assessment connected with practical applications of photovoltaic generation and discuss major points of controversy concerning such issues as comparisons between DC and AC systems and between centrifugal and positive displacement pumps for water pumping units. The advantages and disadvantages of each approach are pointed out, and it is concluded that, in most cases, the specific conditions and requirements must be carefully considered in order to reach the optimum design of a photovoltaic system. The experience obtained from the operation of a photovoltaic water pumping system on the island of Karpathos, Greece, is discussed.<>
{"title":"Assessment of solar photovoltaic systems at the level of rural electrification","authors":"C.A. Kagarakis, J. Avaritsiotis","doi":"10.1109/MELCON.1989.49974","DOIUrl":"https://doi.org/10.1109/MELCON.1989.49974","url":null,"abstract":"The authors outline some of the main problems of design and assessment connected with practical applications of photovoltaic generation and discuss major points of controversy concerning such issues as comparisons between DC and AC systems and between centrifugal and positive displacement pumps for water pumping units. The advantages and disadvantages of each approach are pointed out, and it is concluded that, in most cases, the specific conditions and requirements must be carefully considered in order to reach the optimum design of a photovoltaic system. The experience obtained from the operation of a photovoltaic water pumping system on the island of Karpathos, Greece, is discussed.<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"63 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116908346","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 : 1989-04-11DOI: 10.1109/MELCON.1989.50036
A. Fred, J. Leitao, T. Paiva, J. Tome
An automatic classification system of electroencephalographic data, BIAC (brain imaging and automatic classification), is presented. Special emphasis is placed on exploring topographic imaging for classification purposes and performing correlation analysis between channels in order to find a pattern of normality. The methods were applied to visual-evoked potentials, and classification was made in terms of the normality of the signals from two populations: controls and patients with hepatic cirrhosis. It was shown that symmetry features, being simple measures on topographic maps for particular time instants, are able to discriminate between populations. Correlation features evidenced different patterns for the two populations under study. The selection of four of these features proved useful in discriminating between the populations.<>
提出了一种脑电图数据自动分类系统BIAC (brain imaging and automatic classification)。特别强调探索地形成像的分类目的和执行通道之间的相关性分析，以找到一个模式的正态性。将这些方法应用于视觉诱发电位，并根据两组人群(对照组和肝硬化患者)信号的正常程度进行分类。研究表明，对称特征是地形图上特定时刻的简单度量，能够区分人群。相关特征证明了所研究的两个种群的不同模式。事实证明，选择其中的四个特征对种群之间的区分是有用的。
{"title":"Topographic mapping and automatic classification of electroencephalographic signals","authors":"A. Fred, J. Leitao, T. Paiva, J. Tome","doi":"10.1109/MELCON.1989.50036","DOIUrl":"https://doi.org/10.1109/MELCON.1989.50036","url":null,"abstract":"An automatic classification system of electroencephalographic data, BIAC (brain imaging and automatic classification), is presented. Special emphasis is placed on exploring topographic imaging for classification purposes and performing correlation analysis between channels in order to find a pattern of normality. The methods were applied to visual-evoked potentials, and classification was made in terms of the normality of the signals from two populations: controls and patients with hepatic cirrhosis. It was shown that symmetry features, being simple measures on topographic maps for particular time instants, are able to discriminate between populations. Correlation features evidenced different patterns for the two populations under study. The selection of four of these features proved useful in discriminating between the populations.<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"111 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117180499","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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