Methods of distinguishing sea targets from clutter on a civil marine radar

Mathematical expressions for the signal received from isolated targets and clutter are analysed to show how the signal/clutter ratio is influenced by the parameters of the radar set. Graphs of signal amplitudes are then used to indicate the characteristics of the signals which can be exploited to improve the observed signal/clutter ratio. The limitations introduced by the display and the techniques used to overcome them are described. Change of wavelength is often suggested to improve the signal/clutter ratio. It is shown from independent reports that the effect is small and is swamped by the limitations of the display, in some cases at least by nonuse of the signal processing controls¿swept gain, differentiation and gain. Other possible techniques are examined, and reasons are given as to why they are not in use on current civil marine radars. It is then shown that such equipment is already operating close to limits set by components and space on board ships, so that improvement is only possible by changes in the processing controls, and better use of them by the operator.