CPMFSK as a Modulation on the VLF-HF Atmospheric Channel.
Final technical rept. 16 Aug 76-31 May 77,
GTE SYLVANIA INC NEEDHAM HEIGHTS MASS ELECTRONIC SYSTEMS GROUP-EASTERN DIV
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Continuous phase multi-frequency shift keying CPMFSK is investigated as a potential modulation on the VLF-HF additive atmospheric noise channel. The effects of pre-detection filtering and general concerns of receiver design are addressed. Monte Carlo simulation is used to evaluate the error rate performance of CPMFSK in terms of E sub bsigma squared where E sub b is the energy per bit and sigma squared is the received atmospheric noise variance. The error rate performance is determined for linear receivers as well as non-linear receivers consisting of linear receivers preceded by a zero-memory nonlinearity, such as a clipper or a hole puncher. In addition to the Monte Carlo simulation approach to error rate performance, a theoretical approach to analytically estimate error rate was begun, and the present status of this approach is documented herein. In the attempt to derive theoretical estimates of error-rate performance, it was found necessary to derive and evaluate mathematically tractable atmospheric noise models. These models are constrained to match some of the empirically determined first-order statistics of the atmospheric channel. Finally, transmitted signal power spectral densities p.s.d. are derived and displayed for the modulations of interest.
- Radiofrequency Wave Propagation
- Radio Communications