Accession Number : AD0700153

Title :   RESULTS OBTAINED BY USE OF A THRESHOLD EXTENSION TECHNIQUE ON TWO DIGITAL TROPOSCATTER LINKS.

Descriptive Note : Final technical rept.

Corporate Author : PAGE COMMUNICATIONS ENGINEERS INC WASHINGTON D C

Report Date : DEC 1969

Pagination or Media Count : 115

Abstract : Troposcatter communications experiments were conducted to determine the performance improvements which result when threshold extension panels are incorporated as part of the AN/MRC-98 Radio Set. The type of threshold extension was FM feedback. The tests were performed on path lengths of 382 and 168 miles in the Caribbean Area and New York State. Simultaneous comparisons of digital error rates with and without threshold extension in a quadruple, dual and non-diversity combining mode have been performed on a 24 channel FDM/FM system. The performance was the bit error rate of a 2.4 Kb/s and 40.8 Kb/s modem operated through a voice/group channel. Experimental data for approximately 400 test periods, each of 5 minutes duration, was recorded. It was concluded that threshold extension offers an improvement which tends to increase with increasing median carrier level. The improvement for the system tested was on the order of 2 to 3 decibels. (Author)

Descriptors :   (*COMMUNICATION AND RADIO SYSTEMS, TROPOSPHERE), DIGITAL SYSTEMS, DIVERSITY RECEPTION, RADIO RECEIVERS, FEEDBACK, FREQUENCY MODULATION, ERRORS, SCATTERING

Subject Categories : Radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE