International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / This paper will discuss the performance of pulse code modulation (PCM)/frequency
modulation (FM) during frequency selective fading. Frequency selective fading occurs
when the attenuation in part of the frequency band of interest is much greater than in
the rest of the band of interest. The frequency selective fading model used in this
paper assumes that two paths with different delays exist between the transmitter and
receiver (multipath). The two-path model was simulated in the laboratory and the
effects of frequency selective fading on the radio frequency (RF) spectrum and on the
waveforms at the output of the FM demodulator were measured. A mathematical
model was also used to predict the effects of frequency selective fading. The predicted
waveshapes are compared with the laboratory data. A simple demodulator which
alleviates the effects of frequency selective fading on PCM/FM at moderate
signal-to-noise ratios (SNRs) will be described. This demodulator is created by
detuning the telemetry receiver by a frequency equal to approximately one-half of the
intermediate frequency (IF) bandwidth and using the receiver’s amplitude modulation
(AM) detector output rather than the FM detector output. The performance of this
offset AM demodulator will be compared with the performance of an FM
demodulator. Frequency selective fades measured in real-world environments will be
also presented.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/608409 |
| Date | 11 1900 |
| Creators | Law, Eugene L. |
| Contributors | NAWCWPNS |
| Publisher | International Foundation for Telemetering |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Proceedings |
| Rights | Copyright © International Foundation for Telemetering |
| Relation | http://www.telemetry.org/ |
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