A mathematical analysis of collision-course prediction by Doppler radar

The usefulness of radar plotting as at present practised at sea may be considerably enhanced by the application of a proposed Doppler radar technique which gives instantaneous measurement of relative velocity components and facilitates the whole plotting process. The paper sets out the equations of relative motion and shows how they are related to the observable Doppler frequency. In the system proposed the range and bearing of the target are given by a conventional radar p.p.i., from which change of bearing may also be determined. The Doppler radar gives an immediate measurement of the radial component of relative velocity and the derivative of radial velocity: from these data the course and speed of the target may readily be determined, using an automatic computer if so desired. Possible errors in deducing the true course and speed of the target are examined, and the mode of operation and principal design parameters of a suitable Doppler radar are discussed.