Doppler compensation for orthogonal netted radar systems

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 hybrid polyphase code set which combines single frequency pulse with the designed orthogonal polyphase signal, is presented to implement Doppler compensation and keep ONRS a good resilience to Doppler shifts. Doppler frequency of the target is firstly estimated based on interpolated FFT in the time span of single frequency pulse and the Doppler compensated signal can be constructed to maintain Doppler tolerance. The construction of Doppler compensated signals is illustrated. Simulation results show that the proposed hybrid polyphase code set is effective for moving target detection in ONRS.