Distributed spaceborne SAR can produce SAR images with different scattering spectrum.The combination of these SAR images was used to improve the range resolution in final image product.The key point in its data processing was how to correctly join these different spectrums to a wider range spectrum.A new algorithm based on spectrum shift estimation for improving range resolution was proposed to process distributed spaceborne SAR data.The algorithm firstly estimated the spectrum shift between SAR complex images acquired by small satellites.Then the spectrum shift was compensated to these complex images in frequency field.Finally the compensated SAR images were added to form final image with improved range resolution.According to SAR complex image model

the new algorithm was derived.The steps to implement the algorithm mainly included image registration

spectrum shift estimation

spectrum shift compensation and image addition and every step was presented in detail.FFT were used in the algorithm to reduce its processing time.In last

computer simulation was employed to test the new algorithm.