Digital Implementation of Pulse Compression Technique for X-band Radar

Abstract

The performance of conventional pulsed radars is limited by its time-bandwidth product. In order to get high range resolution, a narrow pulse is required to be transmitted. However, this reduces the average transmit power resulting into shorter detection range. To mitigate this limitation of time-bandwidth problem, pulse compression technique is used. Pulse compression technique can be broadly classified as, FM chirp and phase coded. In FM chirp method, a longer duration frequency modulated pulse is transmitted, and on the receiver side matched filter is used to compress the echo signal. This also resolves the targets which may have overlapping returns. Earlier implementation of pulse compression was done using analog circuitry, which has its own limitations. With the availability of high speed digital equipment, it is now possible to implement it in digital domain. This paper presents a digital implementation of LFM pulse compression technique in X-band. Here, we used an arbitrary waveform generator to generate LFM pulse (chirp) at lower frequency band, which is up-converted to X-band by mixing with a carrier of 9.375 GHz for transmission. On receiver side, after translation to lower frequency band, data is acquired by analog to digital converter card and pulse compression algorithm was implemented in computer using MATLAB tool. Various tests were performed to verify pulse compression technique.