ACQUISITION OF FAST FREQUENCY HOPPING AT HF.
Item
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Title
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ACQUISITION OF FAST FREQUENCY HOPPING AT HF.
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Identifier
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AAI8611330
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identifier
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8611330
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Creator
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BOZOVIC, RADOMIR TODOR.
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Contributor
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Donald L. Schilling
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Date
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1986
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Language
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English
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Publisher
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City University of New York.
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Subject
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Engineering, Electronics and Electrical
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Abstract
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In this work we propose an acquisition scheme for a frequency-hopped spread-spectrum signal received over a nonspecular Rayleigh fading multipath channel. We consider relatively fast frequency hopping with a hopping rate of 1 KHz, and 127 different hopping frequencies. We assume that any two hopping frequencies propagate via statistically independent channels, i.e. via channels with statistically independent time and frequency spreading and statistically independent delay times. Also according to the measurement results we assume that the maximum deviation of the delay time from the nominal delay time is (+OR-)1 msec and is uniformly distributed around the nominal delay time. In this case, ignoring the spreading effect, there will be a possible overlapping between only three adjacent hopping frequencies. For such a case we propose an optimum receiver and acquisition scheme whose characteristics are analyzed mathematically and by computer simulation.;We characterize the performance of the acquisition scheme by the probability of detection for given probability of false acquisition when the input signal is white Gaussian noise only. The probability of detection is the probability that, at the end of the observation period, the desired signal code sequence is detected.;In the acquisition scheme the matched filters are approximated by quadrature receivers whose integrators are replaced by low pass RC filters. On this way when input signal is noise alone the output is a one dimensional Markov process, and we are able to calculate the probability of false alarm and therefore the probability of false acquisition when input signal is noise alone.;For a nonspecular Rayleigh fading multipath channel with variable delay time it is impossible to calculate the probability of acquisition and the probability of false acquisition (when signal is present), and therefore computer simulation has been done and simulated results are presented.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Engineering
