Pub Date : 1979-10-01DOI: 10.1109/ISEMC.1979.7568849
P. Excell, G. H. Butcher, D. Howson
Intense RF fields present a hazard to flammable mixtures as sparks may be drawn from metallic structures acting as unintended receiving antennas. The recent history of attempts to quantify this problem is reviewed. Very recent British work has raised many new problems which suggest that the safety standard will have to be very complex if it is not to reach unreasonably pessimistic conclusions (i.e. it must not predict hazards at great distances from transmitters where direct measurements of power available from structures suggest that there is no hazard). Some possible approaches for future attempts to draft such a standard are discussed.
{"title":"Towards a Safety Standard for Radiofrequency Hazards to Flammable Mixtures - Progress and Problems","authors":"P. Excell, G. H. Butcher, D. Howson","doi":"10.1109/ISEMC.1979.7568849","DOIUrl":"https://doi.org/10.1109/ISEMC.1979.7568849","url":null,"abstract":"Intense RF fields present a hazard to flammable mixtures as sparks may be drawn from metallic structures acting as unintended receiving antennas. The recent history of attempts to quantify this problem is reviewed. Very recent British work has raised many new problems which suggest that the safety standard will have to be very complex if it is not to reach unreasonably pessimistic conclusions (i.e. it must not predict hazards at great distances from transmitters where direct measurements of power available from structures suggest that there is no hazard). Some possible approaches for future attempts to draft such a standard are discussed.","PeriodicalId":283257,"journal":{"name":"1979 IEEE International Symposium on Electromagnetic Compatibility","volume":"108 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132301561","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 : 1979-10-01DOI: 10.1109/ISEMC.1979.7568850
Richard W. Boettcher, Alan K. Johnson
An analysis procedure is described for use in determining the steady-state EMC margin in a spacecraft primary power distribution system. The analysis begins with estimates of broadband and narrowband emissions from each equipment unit. These are combined at the power source impedance to produce a bus ripple voltage spectrum which is then compared to the equipment susceptibility specification. Thus, the three variables of emission, susceptibility and source impedance are related in such a manner that specification tailoring can be performed and design tradeoffs can be evaluated.
{"title":"Tailoring EMI Specifications for Spacecraft Electrical Power System Compatibility","authors":"Richard W. Boettcher, Alan K. Johnson","doi":"10.1109/ISEMC.1979.7568850","DOIUrl":"https://doi.org/10.1109/ISEMC.1979.7568850","url":null,"abstract":"An analysis procedure is described for use in determining the steady-state EMC margin in a spacecraft primary power distribution system. The analysis begins with estimates of broadband and narrowband emissions from each equipment unit. These are combined at the power source impedance to produce a bus ripple voltage spectrum which is then compared to the equipment susceptibility specification. Thus, the three variables of emission, susceptibility and source impedance are related in such a manner that specification tailoring can be performed and design tradeoffs can be evaluated.","PeriodicalId":283257,"journal":{"name":"1979 IEEE International Symposium on Electromagnetic Compatibility","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117001614","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 : 1979-10-01DOI: 10.1109/ISEMC.1979.7568807
D. Clifford, K. S. Zeisel
The time history of a long-spark discharge to a simulated in-flight aircraft and the corresponding transient signals induced on an internal wire pair were measured in this study. Three separate induced coupling conditions related to the aircraft/lightning interaction process have been identified, and each condition has been studied. The three laboratory conditions are believed to be analogous, respectively, to (a) nearby lightning, (b) stepped-leader attachment and (c) return stroke discharge. A unique arrangement of high-voltage (long-spark) generators, electrically floating E-field sensors, fiber optic data links and transient digital recorders was used in this study. Using this equipment, high-voltage shock excitation tests have been developed for each condition and have been labeled E-dot, V-dot and I-dot, respectively, since in each case the induced coupling depends upon the time rate of change of the excitation source. This paper describes the test techniques and the experimental studies leading to the identification of the three test conditions.
{"title":"Evaluation of Lightning-Induced Transients in Aircraft Using High-Voltage Shock Excitation Techniques","authors":"D. Clifford, K. S. Zeisel","doi":"10.1109/ISEMC.1979.7568807","DOIUrl":"https://doi.org/10.1109/ISEMC.1979.7568807","url":null,"abstract":"The time history of a long-spark discharge to a simulated in-flight aircraft and the corresponding transient signals induced on an internal wire pair were measured in this study. Three separate induced coupling conditions related to the aircraft/lightning interaction process have been identified, and each condition has been studied. The three laboratory conditions are believed to be analogous, respectively, to (a) nearby lightning, (b) stepped-leader attachment and (c) return stroke discharge. A unique arrangement of high-voltage (long-spark) generators, electrically floating E-field sensors, fiber optic data links and transient digital recorders was used in this study. Using this equipment, high-voltage shock excitation tests have been developed for each condition and have been labeled E-dot, V-dot and I-dot, respectively, since in each case the induced coupling depends upon the time rate of change of the excitation source. This paper describes the test techniques and the experimental studies leading to the identification of the three test conditions.","PeriodicalId":283257,"journal":{"name":"1979 IEEE International Symposium on Electromagnetic Compatibility","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123238153","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 : 1979-10-01DOI: 10.1109/ISEMC.1979.7568834
W. Kuebler
In EMC analysis, it is often required to assess the mutual interference between stations without knowledge of the antenna patterns involved. Typically only the mainbeam gain is available from large scale spectrum data management systems. This paper concerns itself with a simple methodolgy to synthesize, in a somewhat deterministic manner, an antenna pattern from this insufficient information. Results based on synthesized patterns are compared with measured antenna patterns.
{"title":"A Note on an Idealized Antenna Pattern","authors":"W. Kuebler","doi":"10.1109/ISEMC.1979.7568834","DOIUrl":"https://doi.org/10.1109/ISEMC.1979.7568834","url":null,"abstract":"In EMC analysis, it is often required to assess the mutual interference between stations without knowledge of the antenna patterns involved. Typically only the mainbeam gain is available from large scale spectrum data management systems. This paper concerns itself with a simple methodolgy to synthesize, in a somewhat deterministic manner, an antenna pattern from this insufficient information. Results based on synthesized patterns are compared with measured antenna patterns.","PeriodicalId":283257,"journal":{"name":"1979 IEEE International Symposium on Electromagnetic Compatibility","volume":"135 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124339427","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 : 1979-10-01DOI: 10.1109/ISEMC.1979.7568799
J. Thomson
The major emphasis in EMC for aircraft and flight weapons systems must be in areas where its neglect can hazard flight safety or mission success. RAE's research programme is outlined and reviewed to show how the EMC problem is being tackled from source, through coupling mechanism, to susceptible systems.
{"title":"The RAE Research and Development Programme on EMC for Aircraft and Flight Weapons Systems","authors":"J. Thomson","doi":"10.1109/ISEMC.1979.7568799","DOIUrl":"https://doi.org/10.1109/ISEMC.1979.7568799","url":null,"abstract":"The major emphasis in EMC for aircraft and flight weapons systems must be in areas where its neglect can hazard flight safety or mission success. RAE's research programme is outlined and reviewed to show how the EMC problem is being tackled from source, through coupling mechanism, to susceptible systems.","PeriodicalId":283257,"journal":{"name":"1979 IEEE International Symposium on Electromagnetic Compatibility","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128528876","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 : 1979-10-01DOI: 10.1109/ISEMC.1979.7568792
J. Robb, D. Brady, L. Donatich
In early researches very occasional precipitation static was reported at VHF frequencies. With increasing IFR traffic density, even occasional interference can be serious and for military operations, interference on communications channels can present a serious hazard during ground controlled instrument approaches as well as jeopardizing possible mission success. Experimental investigations of military and commercial aircraft have disclosed that the severe interference is caused by electrically isolated metallic sections on the aircraft exterior which become charged by frictional contact with atmospheric particles and then sparkover to the airframe. This results in a severe broadband interference spectrum centered at a wavelength corresponding to the dimensions of the section which is sparking. Although this type of interference has been previously observed, the investigations again illustrate the severity of the interference and the difficulty in identifying it. Also discovered in the investigations which had not previously been found was receiver desensitization resulting from corona discharges from commercial grounded type VHFUHF antennas. This can occur without the flight crew being aware of it. This investigation indicates that all VHF-UHF antennas having corona discharges from exposed metallic extremities may suffer this desensitization while in flight without the flight crew being aware of it as the interference does not break the squelch. The magnitude of the desensitization may reach 30 db. The impact of this phenomena on commercial airline and military operations, where ground controlled approach may be the only type of instrument approach available for some aircraft, suggests a serious potential problem which needs to be identified and corrected.
{"title":"VHF-UHF Precipitation-Static Interference Effects on Aircraft","authors":"J. Robb, D. Brady, L. Donatich","doi":"10.1109/ISEMC.1979.7568792","DOIUrl":"https://doi.org/10.1109/ISEMC.1979.7568792","url":null,"abstract":"In early researches very occasional precipitation static was reported at VHF frequencies. With increasing IFR traffic density, even occasional interference can be serious and for military operations, interference on communications channels can present a serious hazard during ground controlled instrument approaches as well as jeopardizing possible mission success. Experimental investigations of military and commercial aircraft have disclosed that the severe interference is caused by electrically isolated metallic sections on the aircraft exterior which become charged by frictional contact with atmospheric particles and then sparkover to the airframe. This results in a severe broadband interference spectrum centered at a wavelength corresponding to the dimensions of the section which is sparking. Although this type of interference has been previously observed, the investigations again illustrate the severity of the interference and the difficulty in identifying it. Also discovered in the investigations which had not previously been found was receiver desensitization resulting from corona discharges from commercial grounded type VHFUHF antennas. This can occur without the flight crew being aware of it. This investigation indicates that all VHF-UHF antennas having corona discharges from exposed metallic extremities may suffer this desensitization while in flight without the flight crew being aware of it as the interference does not break the squelch. The magnitude of the desensitization may reach 30 db. The impact of this phenomena on commercial airline and military operations, where ground controlled approach may be the only type of instrument approach available for some aircraft, suggests a serious potential problem which needs to be identified and corrected.","PeriodicalId":283257,"journal":{"name":"1979 IEEE International Symposium on Electromagnetic Compatibility","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129632443","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 : 1979-10-01DOI: 10.1109/ISEMC.1979.7568791
R. A. Pearlman
The results of the return stroke modeling suggests that the path tortuosity is not a major factor in the nearby induced fields. The electric field in the vicinity of the channel is predominantly electrostatic and proportional to the reciprocal of the wave velocity. The shapes of the predicted waveforms are Consistent with field measurements of nearby lightning. The large magnitude of all field components in the vicinity of the channel suggests that a nearby strike could pose a real threat to aircraft electrical systems, even though the aircraft itself is not struck.
{"title":"Lightning Near Fields Generated by Return Stroke Current","authors":"R. A. Pearlman","doi":"10.1109/ISEMC.1979.7568791","DOIUrl":"https://doi.org/10.1109/ISEMC.1979.7568791","url":null,"abstract":"The results of the return stroke modeling suggests that the path tortuosity is not a major factor in the nearby induced fields. The electric field in the vicinity of the channel is predominantly electrostatic and proportional to the reciprocal of the wave velocity. The shapes of the predicted waveforms are Consistent with field measurements of nearby lightning. The large magnitude of all field components in the vicinity of the channel suggests that a nearby strike could pose a real threat to aircraft electrical systems, even though the aircraft itself is not struck.","PeriodicalId":283257,"journal":{"name":"1979 IEEE International Symposium on Electromagnetic Compatibility","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130611598","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 : 1979-10-01DOI: 10.1109/ISEMC.1979.7568804
D. Clifford, E. Krider, M. Uman
Recent measurements of lightning return stroke currents made using both direct and indirect techniques are reviewed and summarized. The data indicate that return stroke current pulses exhibiting submicrosecond rise times are common. Slower rise times reported previously may have been due to instrumentation limitations and, in some cases, to the investigator's definition of rise time. The earlier measurements led to the 2 x 50-microsecond current waveform which is the basis for lightning simulation specifications used in the aerospace industry. Laboratory induced-coupling studies and theoretical considerations are reported which indicate that, for aircraft work, use of the traditional 2x50-microsecond waveform represents inadequate testing, since the more realistic, faster pulses contain frequency components in the range of aircraft system resonances.
回顾和总结了最近使用直接和间接技术测量的雷击回击电流。数据表明，具有亚微秒上升时间的回冲程电流脉冲是常见的。先前报道的较慢的上升时间可能是由于仪器的限制，在某些情况下，研究人员对上升时间的定义。早期的测量产生了2 x 50微秒的电流波形，这是航空航天工业中使用的闪电模拟规范的基础。实验室诱导耦合研究和理论考虑报告表明，对于飞机工作，使用传统的2x50微秒波形代表不充分的测试，因为更现实，更快的脉冲包含飞机系统共振范围内的频率成分。
{"title":"A Case for Submicrosecond Rise-Time Lightning Current Pulses for Use in Aircraft Induced-Coupling Studies","authors":"D. Clifford, E. Krider, M. Uman","doi":"10.1109/ISEMC.1979.7568804","DOIUrl":"https://doi.org/10.1109/ISEMC.1979.7568804","url":null,"abstract":"Recent measurements of lightning return stroke currents made using both direct and indirect techniques are reviewed and summarized. The data indicate that return stroke current pulses exhibiting submicrosecond rise times are common. Slower rise times reported previously may have been due to instrumentation limitations and, in some cases, to the investigator's definition of rise time. The earlier measurements led to the 2 x 50-microsecond current waveform which is the basis for lightning simulation specifications used in the aerospace industry. Laboratory induced-coupling studies and theoretical considerations are reported which indicate that, for aircraft work, use of the traditional 2x50-microsecond waveform represents inadequate testing, since the more realistic, faster pulses contain frequency components in the range of aircraft system resonances.","PeriodicalId":283257,"journal":{"name":"1979 IEEE International Symposium on Electromagnetic Compatibility","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127068431","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 : 1979-10-01DOI: 10.1109/ISEMC.1979.7568851
M. Frazier, J. J. Krstansky, R. Liebl, D. Pridmore
A rationale, based on a literature survey, has been developed to establish test limits for digital industrial control equipment intended to be installed in commercial buildings in urban and suburban areas. No widely accepted comprehensive susceptibility specification exists for such commercial equipments. This paper has attempted to incorporate the most relevant and realistic aspects of existing standards and suggested limits for other equipments and environments, modifying these where deemed necessary to reflect information found in the literature and our own engineering judgement. It is felt that designing equipments that they conform to these suggested limits will result in systems that will be compatible with EM environments that are likely to be encountered, without encountering unrealistic costs due to over-protection.
{"title":"A Rationale for Susceptibility Limits for Commercial Digital Control Equipments","authors":"M. Frazier, J. J. Krstansky, R. Liebl, D. Pridmore","doi":"10.1109/ISEMC.1979.7568851","DOIUrl":"https://doi.org/10.1109/ISEMC.1979.7568851","url":null,"abstract":"A rationale, based on a literature survey, has been developed to establish test limits for digital industrial control equipment intended to be installed in commercial buildings in urban and suburban areas. No widely accepted comprehensive susceptibility specification exists for such commercial equipments. This paper has attempted to incorporate the most relevant and realistic aspects of existing standards and suggested limits for other equipments and environments, modifying these where deemed necessary to reflect information found in the literature and our own engineering judgement. It is felt that designing equipments that they conform to these suggested limits will result in systems that will be compatible with EM environments that are likely to be encountered, without encountering unrealistic costs due to over-protection.","PeriodicalId":283257,"journal":{"name":"1979 IEEE International Symposium on Electromagnetic Compatibility","volume":"160 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123583188","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 : 1979-10-01DOI: 10.1109/ISEMC.1979.7568785
A. A. Hernandez
A computer simulation model developed for determining the manner in which various types of undesired signals affect the performance of FDM/FM receivers is outlined. Continuous wave, frequency modulation, frequency division multiplex-frequency modulation, pulse (chirped and nonchirped), binary phase shift keying and quadrature phase shift keying interference signals were modeled. In addition to these interference signals, white Gaussian noise was modeled. The desired (test tone)-to-undesired signal power ratio at the output of a user selected demultiplexer channel was one of the performance measures computed. The model was validated by comparing model predictions with measured data for a 600-channel FDM/FM system.
{"title":"A Model for Time Waveform Simulation of FDM/FM Receivers","authors":"A. A. Hernandez","doi":"10.1109/ISEMC.1979.7568785","DOIUrl":"https://doi.org/10.1109/ISEMC.1979.7568785","url":null,"abstract":"A computer simulation model developed for determining the manner in which various types of undesired signals affect the performance of FDM/FM receivers is outlined. Continuous wave, frequency modulation, frequency division multiplex-frequency modulation, pulse (chirped and nonchirped), binary phase shift keying and quadrature phase shift keying interference signals were modeled. In addition to these interference signals, white Gaussian noise was modeled. The desired (test tone)-to-undesired signal power ratio at the output of a user selected demultiplexer channel was one of the performance measures computed. The model was validated by comparing model predictions with measured data for a 600-channel FDM/FM system.","PeriodicalId":283257,"journal":{"name":"1979 IEEE International Symposium on Electromagnetic Compatibility","volume":"143 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1979-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121363723","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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