Phase-locked upconvertors in synthesisers for agile pulse-compression radars

The paper describes a synthesiser for an agile radar and, in particular, the use of a phase-locked upconvertor to generate a swept frequency, pulse-compression transmitter drive. The phase-locked upconvertor offers considerable advantages in respect of suppression of the unwanted mixer sideband, efficient generation of power at usefully high levels and compactness of construction when compared with conventional mixer and filter techniques. Pusle-compression theory is reviewed and techniques of signal weighting, as a means of improving rader system performance, are described to illustrate `paired-echo theory¿, which is extended to a more general form enabling the distortion introduced by the phase-locked loop transient to be analysed. A practical upconvertor is described and the effect of the loop transient oscillation on the compressed pulse is assessed for both unweighted and phase-weighted signals. The conculsion of the paper is that phase-locked upconverstion is a feasible, technique, pulse-compression signals having a high immunity to phase errors at the edge of the sweep. The paper supports, with its practical example, an opinion to this effect expressed by Klauder in a well known paper.