Accession Number : AD0855725

Title :   Synthetic HF Environment.

Descriptive Note : Final rept. May 67-Jun 68,

Corporate Author : COMMUNICATIONS AND SYSTEMS INC PARAMUS NJ

Personal Author(s) : Klein, Melvin S.

Report Date : JUN 1969

Pagination or Media Count : 63

Abstract : The purpose of this program was to provide a laboratory instrument that would accurately reproduce most of the channel impairments encountered by HF communication systems using ground-ground and air-ground links. A novel approach to obtain the performance specified for the HF simulator was a high-speed random access core memory as a variable multiple-tapped delay line, with the phase and attenuation of each tap under the real-time control of a small stored-program digital computer. The equipment was designed to reproduce the fine-grain multipath and fading characteristics of the HF medium in a pseudorandom sequence that is precisely repeatable at the operator's discretion. Except for an input level adjustment, all parameter adjustments are made in the form of keyboard entries, as part of an operator-machine dialog. The acceptance tests demonstrated that the simulator accurately reproduces the channel impairments encountered on HF communication systems. The instrument provides operator control of fade rate, additive noise, specular-to-Rayleigh ratio, multipath spread, median level, number of paths, and Doppler shift. (Author)

Descriptors :   (*RADIO TRANSMISSION, IONOSPHERIC PROPAGATION), (*COMMUNICATION AND RADIO SYSTEMS, SIMULATORS), HIGH FREQUENCY, MULTIPATH TRANSMISSION, CORE STORAGE, MAGNETIC CORES, DELAY LINES, NOISE(RADIO), DOPPLER EFFECT.

Subject Categories : Radiofrequency Wave Propagation
      Radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE