Radar Signal Processing for Long Coherent Integration Times and Large Time-Bandwidth Products Using the Keystone Transform

Sammanfattning

This thesis investigates Keystone-based signal processing methods for correcting range migration in pulsed radar systems with long coherent processing intervals. Using the implicit delay model proposed by Kelly and Wishner, the propagation delay model has been formulated as a function of range, velocity, and acceleration of the targets. The Linear Keystone Transform (LKT) is then implemented and analysed for several cases with varying radar system and target parameters. From the results, it can be seen that the LKT performs well at compensating for range migration due to the velocity term and restores coherent integration despite crossing multiple range bins. The effectiveness of the LKT deteriorates when acceleration is considered because of the lack of compensation of the quadratic phase terms in the target signal. This is expected given the LKT assumption of constant radial velocity. Other techniques such as Second-Order Keystone Transform (SOKT) and Double Keystone Transform (DKT) are included as theoretical approaches for compensating acceleration-induced effects, but are not implemented in this work. The results show that Keystone Transform is an effective method of improving the performance of long CPIs for constant-velocity targets, while accelerating targets need higher-order compensation.