Accession Number : ADP006134

Title :   Modeling of Wideband HF Channels,

Corporate Author : NATIONAL TELECOMMUNICATIONS AND INFORMATION ADMINISTRATION BOULDER CO INST FO R TELECOMMUNICATION SCIENCES

Personal Author(s) : Nesenbergs, Martin

Report Date : MAY 1987

Pagination or Media Count : 16

Abstract : Laboratory simulation of wideband high frequency (HF) system performance is currently not possible because such simulators do not exists. Moreover, there are no validated HF channel models for bandwidths of the order of one megahertz, on which to base the simulator design. This paper starts with a very brief review of additive distortions, namely noise and interference, in the HF band. It presents an introduction and an appraisal of past narrowband HF models: their background, validation tests, and the NTIA/ITS development of the Watterson's simulator. That laboratory tool, judged best by many, works in real time and offers accurate representation of HF channel bandwidth up to 10 or 12 kHz. In the present study an extension of wideband models is attempted. Unfortunately, it suffers from an apparently serious shortage of measured data for the time-varying channel transfer function. A possible wideband model is hypothesized, conjectures are made, many questions are raised, but hardly any are answered. One is left faced with a requirement for an experimental program that is to ascertain the wideband (1 MHz or more) characteristics of multipath fading for digital radio transmissions in the HF band (2 to 30 MHz) and over propagation paths of interest. (Author)

Descriptors :   *RADIO LINKS, *HIGH FREQUENCY, RADIO INTERFERENCE, NOISE(RADIO), SIMULATION, BROADBAND, SIMULATION, PERFORMANCE(ENGINEERING), TRANSFER FUNCTIONS, FADING(ELECTROMAGNETIC WAVES), SYMPOSIA.

Subject Categories : Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE