Pub Date : 1963-12-01DOI: 10.1109/TSET.1963.4337623
H. Akima
The essential signal-to-noise characteristics of an FM system are studied theoretically, assuming that the transmitted wave is frequency-modulated by a discontinuous signal, which is made by sampling from the original information signal at every sampling point equally spaced by a Nyquist interval and by boxcarring the sampled value over the following interval. Studies are made with a simple model of an FM demodulator of a new type, which may be called the band-dividing FM demodulator. As a result of these studies a limit to the degree of improvement in the threshold of an FM system is obtained. The result obtained here again suggests that it is possible to improve the threshold of the system beyond that of a so-called conventional FM demodulator. It is also shown that the value of the intrinsic signal-to-noise ratio (the ratio of the incoming signal power to the incoming noise power in the baseband bandwidth) at the threshold is not constant but increases with the value of the modulation index. Brief discussions on the threshold effects in the so-called phase-lock and frequency-lock FM demodulators are also given.
{"title":"Theoretical Studies on Signal-to-Noise Characteristics of an FM System","authors":"H. Akima","doi":"10.1109/TSET.1963.4337623","DOIUrl":"https://doi.org/10.1109/TSET.1963.4337623","url":null,"abstract":"The essential signal-to-noise characteristics of an FM system are studied theoretically, assuming that the transmitted wave is frequency-modulated by a discontinuous signal, which is made by sampling from the original information signal at every sampling point equally spaced by a Nyquist interval and by boxcarring the sampled value over the following interval. Studies are made with a simple model of an FM demodulator of a new type, which may be called the band-dividing FM demodulator. As a result of these studies a limit to the degree of improvement in the threshold of an FM system is obtained. The result obtained here again suggests that it is possible to improve the threshold of the system beyond that of a so-called conventional FM demodulator. It is also shown that the value of the intrinsic signal-to-noise ratio (the ratio of the incoming signal power to the incoming noise power in the baseband bandwidth) at the threshold is not constant but increases with the value of the modulation index. Brief discussions on the threshold effects in the so-called phase-lock and frequency-lock FM demodulators are also given.","PeriodicalId":153922,"journal":{"name":"IEEE Transactions on Space Electronics and Telemetry","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1963-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133439019","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 : 1963-09-01DOI: 10.1109/TSET.1963.4337612
R. Huang
It is shown that where the output signal-to-noise ratio is required to be large, the oscillating limiter does not contribute any more signal-to-noise ratio enhancement than the limiter without feedback under the usual assumptions of Gaussian noise and a quasi-sinusoidal signal. However, it is possible that variation of the signal amplitude with frequency and/or nonlinear phase characteristic in the feedback loop of the oscillating limiter may result in an improvement in signal-to-noise ratio over that of a simple limiter.
{"title":"An Analysis of the Oscillating Limiter","authors":"R. Huang","doi":"10.1109/TSET.1963.4337612","DOIUrl":"https://doi.org/10.1109/TSET.1963.4337612","url":null,"abstract":"It is shown that where the output signal-to-noise ratio is required to be large, the oscillating limiter does not contribute any more signal-to-noise ratio enhancement than the limiter without feedback under the usual assumptions of Gaussian noise and a quasi-sinusoidal signal. However, it is possible that variation of the signal amplitude with frequency and/or nonlinear phase characteristic in the feedback loop of the oscillating limiter may result in an improvement in signal-to-noise ratio over that of a simple limiter.","PeriodicalId":153922,"journal":{"name":"IEEE Transactions on Space Electronics and Telemetry","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1963-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129952274","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 : 1963-09-01DOI: 10.1109/TSET.1963.4337613
J. Albus, D. Schaefer
The determination of the aspect or orientation of spin stabilized satellites is vital for the correct interpretation of scientific measurements made on these spacecraft. Aspect information is collected optically from the sun, moon and earth. Little channel capacity is generally available for telemetry of this information. Therefore, completely digital low power aspect sensing and on-board information processing systems have been built and flown on various satellites. Some interesting results of aspect measurements on Explorer XII showed an unexpected increase in spin rate due to solar pressure, and on Explorer XIV an erratic precession history.
{"title":"Satellite Attitude Determination: Digital Sensing and On-Board Processing","authors":"J. Albus, D. Schaefer","doi":"10.1109/TSET.1963.4337613","DOIUrl":"https://doi.org/10.1109/TSET.1963.4337613","url":null,"abstract":"The determination of the aspect or orientation of spin stabilized satellites is vital for the correct interpretation of scientific measurements made on these spacecraft. Aspect information is collected optically from the sun, moon and earth. Little channel capacity is generally available for telemetry of this information. Therefore, completely digital low power aspect sensing and on-board information processing systems have been built and flown on various satellites. Some interesting results of aspect measurements on Explorer XII showed an unexpected increase in spin rate due to solar pressure, and on Explorer XIV an erratic precession history.","PeriodicalId":153922,"journal":{"name":"IEEE Transactions on Space Electronics and Telemetry","volume":"95 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1963-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116267819","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 : 1963-09-01DOI: 10.1109/TSET.1963.4337614
R. T. Dames
Efficient operation of a tracking system requires that certain acquisition aids be available to each station prior to vehicle approach. One method of deriving such aids is based on extrapolation of vehicle position from a set of orbital parameters. Since in general, extrapolation errors tend to increase with time, orbital parameters must be updated periodically to provide for automatic acquisition. A statistical analysis is presented for assessing extrapolation errors in vehicle position. Starting with a set of orbital elements and a prescribed distribution of errors in the latter, an upper bound is obtained for a statistical parameter associated with the magnitude of the vehicle position error vector. This upper bound is time-dependent and is applied to estimate the related errors in acquisition aids. Thus, all estimates depend upon the time lapse which has expired since the orbital parameters were updated. The method of analysis is general and may be applied to a wide class of tracking systems. An example is included to indicate the magnitude of errors for a particular hypothetical vehicle.
{"title":"Probable Accuracy in Acquisition Aids for an Orbiting Vehicle","authors":"R. T. Dames","doi":"10.1109/TSET.1963.4337614","DOIUrl":"https://doi.org/10.1109/TSET.1963.4337614","url":null,"abstract":"Efficient operation of a tracking system requires that certain acquisition aids be available to each station prior to vehicle approach. One method of deriving such aids is based on extrapolation of vehicle position from a set of orbital parameters. Since in general, extrapolation errors tend to increase with time, orbital parameters must be updated periodically to provide for automatic acquisition. A statistical analysis is presented for assessing extrapolation errors in vehicle position. Starting with a set of orbital elements and a prescribed distribution of errors in the latter, an upper bound is obtained for a statistical parameter associated with the magnitude of the vehicle position error vector. This upper bound is time-dependent and is applied to estimate the related errors in acquisition aids. Thus, all estimates depend upon the time lapse which has expired since the orbital parameters were updated. The method of analysis is general and may be applied to a wide class of tracking systems. An example is included to indicate the magnitude of errors for a particular hypothetical vehicle.","PeriodicalId":153922,"journal":{"name":"IEEE Transactions on Space Electronics and Telemetry","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1963-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129865156","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 : 1963-09-01DOI: 10.1109/TSET.1963.4337617
J. Hansen
In the interest of more efficient operation, a system is proposed which combines the functions of command, synchronization, range, and range rate on the two-way radio link. Extreme reliability of information transfer is achieved by employing "comma-free" words which have been coded for error detection. Consideration is given to an assumed elemental error probability, corresponding to a conservative signal level Pe = 10-4. The mean time between error for this case is 108 years. The coding is such that synchronization obtains the same high degree of reliability as the information. In addition to the advantages of essentially "error-free" communication, the system offers relative ease of implementation common to the class of cyclic codes.
{"title":"An Integrated \"Error-Free\" Communication System","authors":"J. Hansen","doi":"10.1109/TSET.1963.4337617","DOIUrl":"https://doi.org/10.1109/TSET.1963.4337617","url":null,"abstract":"In the interest of more efficient operation, a system is proposed which combines the functions of command, synchronization, range, and range rate on the two-way radio link. Extreme reliability of information transfer is achieved by employing \"comma-free\" words which have been coded for error detection. Consideration is given to an assumed elemental error probability, corresponding to a conservative signal level Pe = 10-4. The mean time between error for this case is 108 years. The coding is such that synchronization obtains the same high degree of reliability as the information. In addition to the advantages of essentially \"error-free\" communication, the system offers relative ease of implementation common to the class of cyclic codes.","PeriodicalId":153922,"journal":{"name":"IEEE Transactions on Space Electronics and Telemetry","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1963-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121598193","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 : 1963-09-01DOI: 10.1109/TSET.1963.4337611
B. G. Kuhn, K. Morey, W. B. Smith
A high-performance data transmission system, incorporating an efficient discrete signal set and optimum detection techniques, has been developed. Envelope-orthogonal signals in the transmitter and matched filters in the receiver are employed; the system has been given the name Orthomatch. As instrumented now, the system requires 1.6 db more power than calculated for information recovery, and requires effectively 1 db additional power for synchronization. On a calculated basis, Orthomatch at 16 levels requires 5.6 db less power than orthogonal incoherent PCM and 1.9 db less power than biphase PCM. Calculated and measured comparison of Orthomatch and a typical PAM-FM system shows an 11.5 db power advantage for Orthomatch.
{"title":"The Orthomatch Data Transmission System","authors":"B. G. Kuhn, K. Morey, W. B. Smith","doi":"10.1109/TSET.1963.4337611","DOIUrl":"https://doi.org/10.1109/TSET.1963.4337611","url":null,"abstract":"A high-performance data transmission system, incorporating an efficient discrete signal set and optimum detection techniques, has been developed. Envelope-orthogonal signals in the transmitter and matched filters in the receiver are employed; the system has been given the name Orthomatch. As instrumented now, the system requires 1.6 db more power than calculated for information recovery, and requires effectively 1 db additional power for synchronization. On a calculated basis, Orthomatch at 16 levels requires 5.6 db less power than orthogonal incoherent PCM and 1.9 db less power than biphase PCM. Calculated and measured comparison of Orthomatch and a typical PAM-FM system shows an 11.5 db power advantage for Orthomatch.","PeriodicalId":153922,"journal":{"name":"IEEE Transactions on Space Electronics and Telemetry","volume":"27 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1963-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116520596","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 : 1963-09-01DOI: 10.1109/TSET.1963.4337616
C. Laughlin
Increasing interest in coherent PM and FM communication systems using phase-locked demodulators has promoted the development of practical coherent diversity combining systems. Phase-locked loops can convert each received signal of a diversity system to an essentially constant frequency and phase for coherent combination prior to demodulation. When the individual signals are fading with some amount of independence, the properly combined signal has less severe amplitude fluctuations than either signal alone and a diversity improvement results. While practical systems of this type have proved very effective, they have a disadvantage in that each of the phase-locked loops are controlled by the individually fading signals. This paper describes a multiple-input servosystem in which a primary phase-locked loop is controlled by the combined signal while auxiliary loops within the primary loop assure phase coherence. In this way, the full diversity improvement is realized in both locking and in demodulation and the probability of losing lock is correspondingly decreased. The probability of a single-input phase-locked loop losing lock is established and then extended to the case of a slowly fading signal with Rayleigh envelope characteristics. The statistics of two such signals optimally combined are used to arrive at a comparative estimate of the improvement possible. A practical diversity-locked combiner is analyzed and design criteria are established.
{"title":"The Diversity-Locked Loop a Coherent Combiner","authors":"C. Laughlin","doi":"10.1109/TSET.1963.4337616","DOIUrl":"https://doi.org/10.1109/TSET.1963.4337616","url":null,"abstract":"Increasing interest in coherent PM and FM communication systems using phase-locked demodulators has promoted the development of practical coherent diversity combining systems. Phase-locked loops can convert each received signal of a diversity system to an essentially constant frequency and phase for coherent combination prior to demodulation. When the individual signals are fading with some amount of independence, the properly combined signal has less severe amplitude fluctuations than either signal alone and a diversity improvement results. While practical systems of this type have proved very effective, they have a disadvantage in that each of the phase-locked loops are controlled by the individually fading signals. This paper describes a multiple-input servosystem in which a primary phase-locked loop is controlled by the combined signal while auxiliary loops within the primary loop assure phase coherence. In this way, the full diversity improvement is realized in both locking and in demodulation and the probability of losing lock is correspondingly decreased. The probability of a single-input phase-locked loop losing lock is established and then extended to the case of a slowly fading signal with Rayleigh envelope characteristics. The statistics of two such signals optimally combined are used to arrive at a comparative estimate of the improvement possible. A practical diversity-locked combiner is analyzed and design criteria are established.","PeriodicalId":153922,"journal":{"name":"IEEE Transactions on Space Electronics and Telemetry","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1963-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130413921","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 : 1963-06-01DOI: 10.1109/TSET.1963.4337601
Randall M. Mealey
Missfle range instrumentation radars are capable of transmitting pulse code groups in which some of the pulses in each group can be used to convey information from the ground to a space vehicle containing a suitable beacon receiver and decoder. Thus, a one-way communication system is provided with only a small increase in ground and vehicle equipment over that required for the tracking function. Since the system is one way, communication reliability becomes of paramount importance. This paper presents a method of computing bit error rates, word error rates, and frame error rates as a function of the SNR at the beacon receiver. The SNR vs range can then be computed by standard methods to obtain the ground-to-vehicle ranges over which reliable communications can be conducted.
{"title":"A Method for Calculating Error Probabilities in a Radar Communication System","authors":"Randall M. Mealey","doi":"10.1109/TSET.1963.4337601","DOIUrl":"https://doi.org/10.1109/TSET.1963.4337601","url":null,"abstract":"Missfle range instrumentation radars are capable of transmitting pulse code groups in which some of the pulses in each group can be used to convey information from the ground to a space vehicle containing a suitable beacon receiver and decoder. Thus, a one-way communication system is provided with only a small increase in ground and vehicle equipment over that required for the tracking function. Since the system is one way, communication reliability becomes of paramount importance. This paper presents a method of computing bit error rates, word error rates, and frame error rates as a function of the SNR at the beacon receiver. The SNR vs range can then be computed by standard methods to obtain the ground-to-vehicle ranges over which reliable communications can be conducted.","PeriodicalId":153922,"journal":{"name":"IEEE Transactions on Space Electronics and Telemetry","volume":"177 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1963-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114105469","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 : 1963-06-01DOI: 10.1109/TSET.1963.4337604
A. G. Ratz, R. D. Lavin, D. G. Lammers
The need for automatically combining fragmentary telemetry tape records into one complete over-all composite record is discussed. The over-all organization of a tape-editing system is broken down into its two main functions: 1) synchronizing the tape transports, 2) measuring the excellence of the tape signals and then carrying out the diversity combination of these signals to form a new edited record. The problems associated with each function are discussed, and conclusions are reached regarding the final form of a tape editor. Finally, a practical tape editor system illustrating these conclusions is described.
{"title":"Automatic Tape-Editing Equipment","authors":"A. G. Ratz, R. D. Lavin, D. G. Lammers","doi":"10.1109/TSET.1963.4337604","DOIUrl":"https://doi.org/10.1109/TSET.1963.4337604","url":null,"abstract":"The need for automatically combining fragmentary telemetry tape records into one complete over-all composite record is discussed. The over-all organization of a tape-editing system is broken down into its two main functions: 1) synchronizing the tape transports, 2) measuring the excellence of the tape signals and then carrying out the diversity combination of these signals to form a new edited record. The problems associated with each function are discussed, and conclusions are reached regarding the final form of a tape editor. Finally, a practical tape editor system illustrating these conclusions is described.","PeriodicalId":153922,"journal":{"name":"IEEE Transactions on Space Electronics and Telemetry","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1963-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124552130","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 : 1963-06-01DOI: 10.1109/TSET.1963.4337603
J. John, J. Hilliard
An investigation was made of the cooling of power transistors in a space environment, where the only available mode of heat transfer is that of conduction to a heat sink and radiation from the heat sink to space. An attempt was made to minimize the thermal resistance between transistor case and heat sink, allowing the transistor to dissipate as much power as possible while maintaining its temperature within the maximum tolerable level to prevent thermal runaway. Further, it was necessary to electrically insulate the transistor from the heat sink. The use of beryllium oxide washers provided electrical insulation, while adding very little to the thermal resistance between case and sink, the BeO being a good heat conductor. However, the problem of contact thermal resistance at each interface arose, especially in vacuum this contact resistance providing practically al the thermal resistance between case and sink. The effect on the contact resistance of surface pressure, insertion of foils, and soldering was examined. It was concluded that, for most efficient heat sinking, indium foil should be inserted at each interface, the indium foil having the effect of reducing the contact resistance in vacuum by a factor of 8.
{"title":"Heat-Sinking Techniques for Power Transistors in a Space Environment","authors":"J. John, J. Hilliard","doi":"10.1109/TSET.1963.4337603","DOIUrl":"https://doi.org/10.1109/TSET.1963.4337603","url":null,"abstract":"An investigation was made of the cooling of power transistors in a space environment, where the only available mode of heat transfer is that of conduction to a heat sink and radiation from the heat sink to space. An attempt was made to minimize the thermal resistance between transistor case and heat sink, allowing the transistor to dissipate as much power as possible while maintaining its temperature within the maximum tolerable level to prevent thermal runaway. Further, it was necessary to electrically insulate the transistor from the heat sink. The use of beryllium oxide washers provided electrical insulation, while adding very little to the thermal resistance between case and sink, the BeO being a good heat conductor. However, the problem of contact thermal resistance at each interface arose, especially in vacuum this contact resistance providing practically al the thermal resistance between case and sink. The effect on the contact resistance of surface pressure, insertion of foils, and soldering was examined. It was concluded that, for most efficient heat sinking, indium foil should be inserted at each interface, the indium foil having the effect of reducing the contact resistance in vacuum by a factor of 8.","PeriodicalId":153922,"journal":{"name":"IEEE Transactions on Space Electronics and Telemetry","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1963-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133797166","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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