Accession Number : AD0755122

Title :   Effect of the VLF Propagation Channel on Spread-Spectrum Communication Systems.

Descriptive Note : Research and development rept. Mar 71-Jun 72,

Corporate Author : NAVAL ELECTRONICS LAB CENTER SAN DIEGO CALIF

Personal Author(s) : Rothmuller,I. J.

Report Date : 04 AUG 1972

Pagination or Media Count : 69

Abstract : The effect of propagation on the performance of a differentially coherent, MSK communication system having a demodulator not matched to the channel is determined. The system performance level is found to be dependent on the dispersion characteristics of the channel transfer function. Near deep interference minima, performance increased as the bandwidth increased. For the particular sharp null studied, improvement of up to 20 dB above the level expected by a cw system operating at the center frequency was obtained. Up to 4-dB further improvement can be gained at wide bandwidths for sharp, deep nulls by implementation of a demodulator which matches the channel. The extreme phase dispersion at interference minima, which was expected to cause severe degradation, in fact caused only 2-to-3-dB degradation. (Author)

Descriptors :   (*RADIO TRANSMISSION, VERY LOW FREQUENCY), FREQUENCY MODULATION, BANDWIDTH, TRANSFER FUNCTIONS, POWER SPECTRA, INTEGRAL TRANSFORMS, DEMODULATORS, ADAPTIVE SYSTEMS

Subject Categories : Radiofrequency Wave Propagation
      Radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE