Frequency management support for remote sea-state sensing using the JINDALEE skywave radar

Abstract

Successful operation of a skywave (over-the-horizon, OTH) radar in a remote sea-state sensing mode is critically dependent upon the application of comprehensive frequency management techniques. In addition to the problem of selecting a frequency yielding an adequate signal-to-noise ratio in the geographical area under investigation, attention must be paid to minimization of ionospheric multimode and other phenomena capable of distorting or convoluting the sea backscatter spectrum. This paper describes the manner in which these problems have been addressed in the JINDALEE skywave radar, and relates the practical difficulties inherent in the task of frequency management in support of an OTH radar involved in sea-state sensing. Measurement techniques include backscatter and oblique-incidence sounding, HF spectral surveillance, and a low-powered frequency-agile miniradar capable of operating in either a conventional backscatter or alternate oblique-incidence mode. In addition to providing the main radar with real-time frequency management advice, a principal emphasis has been the acquisition of a synoptic data base suitable for off-line statistical analysis.