Evaluation of Coherent FSK Performance in Atmospheric Radio Noise.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OHIO SCHOOL OF ENGINEERING
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Communications in the very low frequencylow frequency range are primarily degraded by the influence of atmospheric radio noise ARN. It is the purpose of this thesis to evaluate the performance of a continuous frequency shift keying CFSK communications system operating in an ARN channel. Beckmanns model for the amplitude probability distribution PDF of the envelope voltage for ARN is used in the analysis. Beckmanns model provides a theoretical foundation for an empirical APD compiled by Crichlow. The parameters for Beckmanns model are determined which give APD curves that correspond to Crichlows statistics for Vd ratios of 4 and 5. The marginal density for the in-phase component of ARN is derived from Beckmanns noise model. The performance of a binary CFSK detector operating in an ARN channel is calculated using the very low frequencylow frequency derived in phase density. The M-ary performance is also calculated is also calculated for M equal to 3 and 4. A comparison is made to experimental CFSK performance data. The theoretical performance curves provide a tight upper bound on the probability of error for the experimental performance. The conclusion is reached that the probability of error for ARN does not decrease significantly with an increase in signal-to-noise ratio. Author
- Atmospheric Physics
- Radio Communications