Pub Date : 1989-04-11DOI: 10.1109/MELCON.1989.50130
A. Martinez Mas, J.E. Fustero, M. Sanz, M. Alvarez-Ossorio
The authors describe and examine the implementation of SITRAL (Servicio Integrado de Telefonia sobre Red de Area Local), a telephony service over an Ethernet local area network, integrating voice and data and providing both the call control procedures and the packetized voice channels on the nodes of the network for internal calls and access to the public network. The different elements of the voice-data nodes are explained. A brief taxonomy of alternative access methods for the voice packets is presented. A telephony service has been shown to be possible over a standard IEEE 802.3 network. Simulation results show that more than a hundred telephones can use the service simultaneously with a data load of 10%.<>
作者描述并研究了SITRAL (service Integrado de Telefonia sobre Red de Area Local)的实现，这是一种以太网局域网上的电话服务，集成了语音和数据，并在网络节点上提供呼叫控制程序和分组语音通道，用于内部呼叫和访问公共网络。解释了语音数据节点的不同元素。简要介绍了话音分组的可选访问方法的分类。在标准的IEEE 802.3网络上，电话服务已被证明是可能的。仿真结果表明，在数据负载为10%的情况下，可实现100多台电话同时使用该服务。
{"title":"SITRAL: an integrated telephony service over a local area network","authors":"A. Martinez Mas, J.E. Fustero, M. Sanz, M. Alvarez-Ossorio","doi":"10.1109/MELCON.1989.50130","DOIUrl":"https://doi.org/10.1109/MELCON.1989.50130","url":null,"abstract":"The authors describe and examine the implementation of SITRAL (Servicio Integrado de Telefonia sobre Red de Area Local), a telephony service over an Ethernet local area network, integrating voice and data and providing both the call control procedures and the packetized voice channels on the nodes of the network for internal calls and access to the public network. The different elements of the voice-data nodes are explained. A brief taxonomy of alternative access methods for the voice packets is presented. A telephony service has been shown to be possible over a standard IEEE 802.3 network. Simulation results show that more than a hundred telephones can use the service simultaneously with a data load of 10%.<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"17 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":"121233697","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.1989.49989
O. Carlson, J. Hylander
The authors describe two variable-speed AC-drive systems: a synchronous generator with frequency converter for large speed ranges and a rotor cascade induction generator for small variations of speed. Results of transient state calculations using computer models and verifying laboratory tests are presented. The synchronous generator system together with a digital control system is being tested on a 40 kW windmill. The converters introduce harmonics into the currents in the generators and thereby into the electrical torque and the shafts of the generators. A temperature rise is caused by the harmonic currents. By current control of the inverters the electrical torque is controlled, and by this control the maximum torque in the drive train of the windmill is limited. Optimal operation can also be achieved in low wind conditions.<>
{"title":"Variable speed AC-generators in wind energy convertors","authors":"O. Carlson, J. Hylander","doi":"10.1109/MELCON.1989.49989","DOIUrl":"https://doi.org/10.1109/MELCON.1989.49989","url":null,"abstract":"The authors describe two variable-speed AC-drive systems: a synchronous generator with frequency converter for large speed ranges and a rotor cascade induction generator for small variations of speed. Results of transient state calculations using computer models and verifying laboratory tests are presented. The synchronous generator system together with a digital control system is being tested on a 40 kW windmill. The converters introduce harmonics into the currents in the generators and thereby into the electrical torque and the shafts of the generators. A temperature rise is caused by the harmonic currents. By current control of the inverters the electrical torque is controlled, and by this control the maximum torque in the drive train of the windmill is limited. Optimal operation can also be achieved in low wind conditions.<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"156 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":"125773761","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.1989.50095
T. Hasan, J. Boucher, Y. Henry
Attention is given to a portable telephone system using direct-sequence spread-spectrum multiple-access and binary phase-shift keying (BPSK) with coherent demodulation. The system has several pairs of base-portable units for each user. Instead of being concentrated in a central point, the base stations are distributed in an area. Each base station, then, serves as the central point of a covering area within which the base-portable pair can communicate. Furthermore, it is assumed that part of each covering area is exclusive to each user and that automatic gain control is used so that the power received by a receiver (mobile or fixed) remains constant. The characteristic function method is used to evaluate the performance of the system.<>
{"title":"A direct-sequence spread-spectrum public portable telephone","authors":"T. Hasan, J. Boucher, Y. Henry","doi":"10.1109/MELCON.1989.50095","DOIUrl":"https://doi.org/10.1109/MELCON.1989.50095","url":null,"abstract":"Attention is given to a portable telephone system using direct-sequence spread-spectrum multiple-access and binary phase-shift keying (BPSK) with coherent demodulation. The system has several pairs of base-portable units for each user. Instead of being concentrated in a central point, the base stations are distributed in an area. Each base station, then, serves as the central point of a covering area within which the base-portable pair can communicate. Furthermore, it is assumed that part of each covering area is exclusive to each user and that automatic gain control is used so that the power received by a receiver (mobile or fixed) remains constant. The characteristic function method is used to evaluate the performance of the system.<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"195 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":"123515968","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.1989.50111
A. Andreatos, E. Protonotarios, G. D. Grandi
The authors describe the architecture and give details on the hardware implementation of a special packet video transceiver, which is appropriate for the communication of broadcast television signals between two stations of an integrated services packet network. The system performs line processing and can detect and/or correct various kinds of errors concerning the reception of packets at the receiver, basically by replacing a wrong or missing packet or line by previously received information from the preceding scan line. Additional information is given about the design and operation of a special frequency-regulation system which the receiver uses to trigger a video digital-to-analog converter which reconverts the digitized video signal into analog form, as well as for a master clock source. This system evaluates the transmitter scanning frequency, basing the evaluation on the timing of the incoming packets. These packets are transmitted through a noisy channel (isochronous network) and are affected by random but bounded delay (jitter).<>
{"title":"The design of a transceiver for packet video communication on an integrated services network","authors":"A. Andreatos, E. Protonotarios, G. D. Grandi","doi":"10.1109/MELCON.1989.50111","DOIUrl":"https://doi.org/10.1109/MELCON.1989.50111","url":null,"abstract":"The authors describe the architecture and give details on the hardware implementation of a special packet video transceiver, which is appropriate for the communication of broadcast television signals between two stations of an integrated services packet network. The system performs line processing and can detect and/or correct various kinds of errors concerning the reception of packets at the receiver, basically by replacing a wrong or missing packet or line by previously received information from the preceding scan line. Additional information is given about the design and operation of a special frequency-regulation system which the receiver uses to trigger a video digital-to-analog converter which reconverts the digitized video signal into analog form, as well as for a master clock source. This system evaluates the transmitter scanning frequency, basing the evaluation on the timing of the incoming packets. These packets are transmitted through a noisy channel (isochronous network) and are affected by random but bounded delay (jitter).<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"1 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":"129756968","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.1989.50116
K. Sylwester
Simple ways to describe a switching network state are presented. The first consists in the description of the state by the set of connecting path numbers, memorized in one word of the specialized memory CAM. The second uses a tabular type of description which can be obtained by transformation of the first description. This description is useful for RAM memory. The use of both control systems for a digital switching network composed of DSM elements is analyzed. Analytical models of reaction time calculation are proposed. The models describe the multislot connections used in ISDN (integrated services digital network).<>
{"title":"Connection path numbering of ISDN multistage time switching networks and its conform to control","authors":"K. Sylwester","doi":"10.1109/MELCON.1989.50116","DOIUrl":"https://doi.org/10.1109/MELCON.1989.50116","url":null,"abstract":"Simple ways to describe a switching network state are presented. The first consists in the description of the state by the set of connecting path numbers, memorized in one word of the specialized memory CAM. The second uses a tabular type of description which can be obtained by transformation of the first description. This description is useful for RAM memory. The use of both control systems for a digital switching network composed of DSM elements is analyzed. Analytical models of reaction time calculation are proposed. The models describe the multislot connections used in ISDN (integrated services digital network).<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"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":"130329856","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.1989.50078
A. Gusmão, N. Esteves
The authors examine the coherent detection of ENCoded-Amplitude-and-Phase (ENCAP) offset quadrature phase shift keying (OQPSK) signals with the help of both QPSK-type (MSK-type) receivers and Viterbi receivers. Numerical results are presented on the performance of parallel and serial OQPSK-type receivers as well as matched and mismatched Viterbi receivers. In some cases where compact spectra are obtained, it turns out that the OQPSK-type receivers are nearly as efficient as the optimal Viterbi receivers, even though the former are much simpler. As for sensitivity to synchronization errors, the Viterbi receivers, even if perfectly matched, are not clearly superior to the OQPSK-type receivers.<>
{"title":"Receiver design and performance evaluation with ENCAP-4/sup N/ digital modulation","authors":"A. Gusmão, N. Esteves","doi":"10.1109/MELCON.1989.50078","DOIUrl":"https://doi.org/10.1109/MELCON.1989.50078","url":null,"abstract":"The authors examine the coherent detection of ENCoded-Amplitude-and-Phase (ENCAP) offset quadrature phase shift keying (OQPSK) signals with the help of both QPSK-type (MSK-type) receivers and Viterbi receivers. Numerical results are presented on the performance of parallel and serial OQPSK-type receivers as well as matched and mismatched Viterbi receivers. In some cases where compact spectra are obtained, it turns out that the OQPSK-type receivers are nearly as efficient as the optimal Viterbi receivers, even though the former are much simpler. As for sensitivity to synchronization errors, the Viterbi receivers, even if perfectly matched, are not clearly superior to the OQPSK-type receivers.<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"33 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":"126695964","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.1989.50006
A. Moura, F.M. Barbosa, Z. Vale
The versatility of Bewley's method for the calculation of transient currents and voltages using personal computers is shown. The computer time and storage required are relatively small. SOBBE program is shown to be an efficient program for the study of transient phenomena of medium-size power system networks. Numerical results are presented.<>
{"title":"Travelling waves methods for the calculation of electrical transients-an efficient computational algorithm of Bewley's method","authors":"A. Moura, F.M. Barbosa, Z. Vale","doi":"10.1109/MELCON.1989.50006","DOIUrl":"https://doi.org/10.1109/MELCON.1989.50006","url":null,"abstract":"The versatility of Bewley's method for the calculation of transient currents and voltages using personal computers is shown. The computer time and storage required are relatively small. SOBBE program is shown to be an efficient program for the study of transient phenomena of medium-size power system networks. Numerical results are presented.<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"39 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":"116485565","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.1989.50139
J. Rebollar, J. Esteban
A generalized scattering matrix of the generalized two-port discontinuity is proposed for use in the analysis, design, and optimization of four-port waveguide directional couplers. The proposed analysis method can consider symmetrical and asymmetrical structures without any geometrical restriction. Agreement with experimental data is excellent. A comparative study of the reflection and coupling performance between branch-waveguide directional couplers and broad wall slot couplers is presented. It is shown that by using branch-waveguide directional couplers a flat coupling can be achieved over a wider bandwidth.<>
{"title":"Comparative study between branch-waveguide directional couplers and broad-wall slot couplers","authors":"J. Rebollar, J. Esteban","doi":"10.1109/MELCON.1989.50139","DOIUrl":"https://doi.org/10.1109/MELCON.1989.50139","url":null,"abstract":"A generalized scattering matrix of the generalized two-port discontinuity is proposed for use in the analysis, design, and optimization of four-port waveguide directional couplers. The proposed analysis method can consider symmetrical and asymmetrical structures without any geometrical restriction. Agreement with experimental data is excellent. A comparative study of the reflection and coupling performance between branch-waveguide directional couplers and broad wall slot couplers is presented. It is shown that by using branch-waveguide directional couplers a flat coupling can be achieved over a wider bandwidth.<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"57 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":"128075525","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.1989.49978
K. Jezernik, M. Milanović, D. Zadravec
The authors describe and analyze two PWM (pulse width modulation) control methods for UPS (uninterruptible power supply) systems. The first method is hysteresis control with a single measure value. The second method is microprocessor-based constant-frequency PWM with a dead-beat controller. Simulation results are presented for a single-phase UPS and a three-phase UPS with a DY transformer using the latter method. It is noted that UPS systems with hysteresis controllers, because of finite turn-on and turn-off times and finite hysteresis width, require a differentiator which is very difficult to implement. PWM with a dead-beat controller has a constant switch frequency; at a switch frequency of 2 kHz, better results were achieved using a smaller LC filter.<>
{"title":"Microprocessor control of PWM inverter for sinusoidal output","authors":"K. Jezernik, M. Milanović, D. Zadravec","doi":"10.1109/MELCON.1989.49978","DOIUrl":"https://doi.org/10.1109/MELCON.1989.49978","url":null,"abstract":"The authors describe and analyze two PWM (pulse width modulation) control methods for UPS (uninterruptible power supply) systems. The first method is hysteresis control with a single measure value. The second method is microprocessor-based constant-frequency PWM with a dead-beat controller. Simulation results are presented for a single-phase UPS and a three-phase UPS with a DY transformer using the latter method. It is noted that UPS systems with hysteresis controllers, because of finite turn-on and turn-off times and finite hysteresis width, require a differentiator which is very difficult to implement. PWM with a dead-beat controller has a constant switch frequency; at a switch frequency of 2 kHz, better results were achieved using a smaller LC filter.<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"13 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":"128123627","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.1989.50144
J. Hénaff
Some examples of university-industry cooperation leading to a suitable engineer's education are considered. The role in this interaction of research centers in research cooperative programs is emphasized. The main cooperative actions between France Telecom, university, and industry are also presented.<>
{"title":"Engineer's education: university-industry interactions","authors":"J. Hénaff","doi":"10.1109/MELCON.1989.50144","DOIUrl":"https://doi.org/10.1109/MELCON.1989.50144","url":null,"abstract":"Some examples of university-industry cooperation leading to a suitable engineer's education are considered. The role in this interaction of research centers in research cooperative programs is emphasized. The main cooperative actions between France Telecom, university, and industry are also presented.<<ETX>>","PeriodicalId":380214,"journal":{"name":"Proceedings. Electrotechnical Conference Integrating Research, Industry and Education in Energy and Communication Engineering',","volume":"25 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":"125716403","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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