Means of improving accuracy of positioning for ocean SAR

Estimation of Doppler central frequency has an important effect to accuracy of fixed position in the fixing approach with no reference points for ocean SAR. The effect of Signal-Noise-Ration (SNR) to the estimation of Doppler central frequency has been studied using theoretical method and simulation technique, and results are given in curves. Based on above results, a Doppler measurement mode is adopted in the design of ocean SAR. Compared to common imaging mode, this mode increases SNR of ocean echo by decreasing the bandwidth, then accuracy of fixed position can be improved.