Optimizing polyphase signals for orthogonal netted radar

Orthogonal netted radar systems (ONRS) can fundamentally improve radar performance by using a group of specially designed orthogonal polyphase code signals. However, the existing numerical solutions only address autocorrelation and cross-correlation properties with the result that the signals degrade severely in the presence of small Doppler shifts. In the context of these problems, a new set of polyphase sequences is presented with good correlation properties as well as resilience to Doppler shifts. These sequences are built using numerical optimization based on correlation properties as well as the Doppler effect on matched filter output, which maintains Doppler tolerance. The statistical simulated annealing algorithm and the greedy code search method are used to optimize the sequences. Correlation and Doppler results are compared with best-known sequences and shown to be superior.