An improved keystone transform implementation and its application in an S-band LFMCW Doppler radar

Abstract

Keystone transform (KT) is a radar signal processing technology, and commonly used in long-time integration to correct target range migration. At present, there are several implementation methods of KT, among which the method based the chirp-z transform (CZT) and inverse fast Fourier transform (IFFT) is the most popular, because of low computational cost and relatively good performance for the simulated data. However, the performance is not the case for the measured data used in this paper, where the datasets are the observations of the vehicles on A13 highway in The Netherlands by an S-band LFMCW radar. As to other implementations, the performance is even worse. For this problem, this paper proposes an improved KT implementation, in which the Mellin transform (MT), an integral transform commonly used in digital image processing, is employed in radar returns to remove the coupling of fast-time and slow-time, and obtains better performance over the existing methods. The computational cost of the proposed method is not very high, because a fast algorithm is used in MT computation. Based on the datasets with more than 60,000 pulses, the performance of the proposed method is fully verified.