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Space Electronics and Telemetry, IEEE Transactions on

Issue 4 • Date Dec. 1963

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Displaying Results 1 - 11 of 11
  • [Table of contents]

    Page(s): c1
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  • IEEE Professional Technical Group on Space Electronics and Telemetry

    Page(s): c2
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  • Theoretical Studies on Signal-to-Noise Characteristics of an FM System

    Page(s): 101 - 108
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    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. View full abstract»

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  • Design of a Digital Notch Filter with Tracking Requirements

    Page(s): 109 - 114
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    The development of a digital filter using sampled data theory techniques and having a desired frequency response characteristic is described. Specifically, design of a digital notch filter is accomplished through formulation of a regression equation for application to sampled input and output values from the filter. After first expressing the desired transfer function in the continous domain, the equation is developed using sampled data theory relationships. Although the techniques are applied to a specific type of filter, they are general in nature. The problem considered involves attenuation of a particular frequency and those in its immediate vicinity while leaving other even slightly distant frequencies relatively unattenuated. An additional requirement calls for tracking and attenuating an input whose frequency is time-variable. In particular, a linearly (with respect to time) variable frequency is considered and discussed. Testing and evaluation were performed through simulation on a general purpose digital computer. Results obtaied are described. View full abstract»

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  • Performance of Hamming Codes

    Page(s): 115 - 126
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    Evaluation of the performance of error-correcting codes has, in the past, been severely hampered by the lack of functional relationships between the uncoded and coded binit error rates. In this paper, such relationships yielding the exact decoder output error rates are developed for Hamming SED codes of lengths n = 2m - 1, m = 1, 2, 3,···, and for Hamming SEC/DED codes of length n = 2m, m = 1, 2, 3,···. In addition, for the DED codes, a similar family of formulas are derived for the probability that a received information binit is contained in a word containing an error pattern that can be detected but not corrected. A criterion of merit for the coded versus uncoded systems is postulated. A similar criterion is developed based upon word error rates. It is demonstrated that the latter results, in general, in highly erroneous conclusions regarding the comparative worth of coded systems. Graphs are presented illustrating the numerical results based on these formulas for codes ranging in length from 7/8 binits up to and including 511/512 binits, for uncoded channel error rates of 0.5 to 10-10. Similar graphs of code merit, based upon modulation systems for which detection is a linear operation (PSK-MF, for example), are constructed. From these, ranges of channel (uncoded) error probability over which particular code lengths result in the best performance that can be obtained from that type of code are extracted and tabulated. View full abstract»

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  • A Note on the Realization of Ambiguity Functions

    Page(s): 127 - 130
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    For various practical reasons, a highly desirable attribute of a realization procedure for the ambiguity function would be control over the envelope of the complex signal modulation. A design procedure is derived which has this property and begins with a specification of the range and Doppler cross sections of the ambiguity function. The essential problem is to find the phase modulation of the signal when the envelopes of the signal and its spectrum are specified; a solution is given for the large time-bandwidth product case. An application to the problem of avoiding range ambiguities is discussed. View full abstract»

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  • Error Rate of PCM-FM Using Discriminator Detection

    Page(s): 131 - 137
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    The probability of error is derived for a PCM-FM system that uses a discriminator as a detector. It is shown that discriminator performance is approximately 1 db poorer than optimum detection of a PCM-FM signal. The results compare favorably with experimental measurments conducted elsewhere. View full abstract»

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  • Contributors

    Page(s): 138 - 139
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  • Index to IEEE Transactions on Space Electronics and Telemetry Volume SET-9, 1963

    Page(s): 1 - 3
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  • Institutional listings

    Page(s): 3a
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Aims & Scope

This Transactions ceased publication in 1965. The new retitled publication is IEEE Transactions on Aerospace and Electronic Systems.

Full Aims & Scope