A narrowband high frequency channel simulator with delay spread

Abstract

It is very difficult to design state-of-the-art HF communication equipment without the ability to test and verify that equipment consistently. RF equipment designers can avoid the pitfalls of inconsistent, unpredictable and costly field-testing by using channel simulators. This paper describes a new channel simulator that includes channel effects that have not been implemented in narrowband simulators to date. Using a wideband high frequency (WBHF) channel model, that was developed by the Institute for Telecommunication Sciences (ITS) and is now under ITU-R consideration, ITS has developed a narrowband high frequency (NBHF) channel simulator that includes delay spread effects. This new simulator eliminates one of the limitations ofthe Watterson NBHF channel model. When the Watterson (1970) model was validated, data was selected which represented quiet ionospheric conditions (no delay spread). There is widespread interest in the effects of delay spread on the NBHF communication equipment. It was with this in mind that ITS set out to create an inexpensive way to evaluate the performance of equipment when confronted with a delay spread. This paper provides an explanation of the application of the ITS WBHF channel model (of which the Watterson model is a limiting case) in a narrowband simulator implemented on a common PC based digital signal processing (DSP) board.