Accession Number : AD0704705

Title :   MULTIPATH PROBLEMS IN TRANSMISSION OF 20 KBIT/S DATA VIA THE VHF-FM MEDIA.

Descriptive Note : Technical rept.,

Corporate Author : ARMY ELECTRONICS COMMAND FORT MONMOUTH N J

Personal Author(s) : Seiler,Thomas M.

Report Date : FEB 1970

Pagination or Media Count : 28

Abstract : In an effort to statistically quantify the tactical VHF-FM media for the transmission of 20 kb/s data in the Payson Area of Central Arizona an interesting phenomenon was observed. Severe amplitude and phase distortion was observed on the digital bit stream when the transmitter was moved through some well-defined regions. It is of interest to note that these regions were fairly common but extremely localized and were surrounded by area where practically no distortion was observed. Thus it was possible to be within visual contact of the receiver, be transmitting good data and move a distance of 6 inches and enter a region of severe distortion which would cause receiver to lose bit synchronization. This phenomenon was attributed to multipath since the received level in the distorted region was not significantly different from that observed in the undistorted region. However, the delays of the various signals causing the multipath are postulated to be multiples of the wavelength of the carrier and are on the order of 50 to 100 nanoseconds. This contention is backed up by both physical and mathematical evidence. (Author)

Descriptors :   (*DATA TRANSMISSION SYSTEMS, *MULTIPATH TRANSMISSION), (*COMMUNICATION AND RADIO SYSTEMS, MULTIPATH TRANSMISSION), VERY HIGH FREQUENCY, FREQUENCY MODULATION, MATHEMATICAL ANALYSIS, ARIZONA

Subject Categories : Radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE