Accession Number : ADB053106
Title : HF Radio Communication Systems Design Assessment. Task 3.3a. Narrow Band Voice Modulation, Optimization of the Frequency.
Descriptive Note : Technical rept. no. 1, 1 Jan-1 Jul 80,
Corporate Author : ROCKWELL INTERNATIONAL RICHARDSON TX COLLINS COMMUNICATIONS SYSTEMS DIV
Personal Author(s) : Dougherty, Steve ; Ambrose, John
Report Date : 01 JUL 1980
Pagination or Media Count : 107
Abstract : Although under perfect non-fading propagation conditions narrow-band FM may be the best modulation technique, HG is not an ideal medium and single sideband, which is only a few dB worse under ideal conditions, continued to be the modulation technique that offers the best performance in the least bandwidth. In addition, for reasons of interoperability with existing and other nations's equipment, radios procured through the early 1990's would have to have single sideband. Moderate amounts of amplitude clipping can offer significant improvements in perceived voice quality. Even stronger clipping or logarithmic amplitude compression combined with an amplitude indicating pilot tone can offer greatly enhanced voice performance under good conditions at the cost of poorer performance under marginal conditions. The continued use a analog voice at HF is suspect because of the requirement for security. Therefore, major investments of research and development funds and time in analog processing of voice for HF transmission can not be encouraged. A single-tone modem with waveforms designed in concert with the radio filters and using an adaptive filter to compensate for the HF path offers the highest efficiency potential for digital voice.
Descriptors : *RADIO ANTIJAMMING, *RADIO EQUIPMENT, *VOICE COMMUNICATIONS, *SINGLE SIDEBAND COMMUNICATIONS, HIGH FREQUENCY, ADAPTIVE SYSTEMS, DIGITAL SYSTEMS, ANALOG SYSTEMS, ADAPTIVE FILTERS, LINE OF SIGHT, PERFORMANCE(ENGINEERING), NARROWBAND, OPTIMIZATION, BANDWIDTH, TRANSMITTANCE, NARROWBAND, INDICATORS, MODULATION, COMPRESSION, EFFICIENCY, PROCESSING, PILOTS, PATHS, AMPLITUDE.
Subject Categories : Radio Countermeasures
Distribution Statement : APPROVED FOR PUBLIC RELEASE