Improved method of pre-weighed Zoom FFT

This paper presents a method to improve pre-weighed zoom FFT (ZFFT) for fast computation of ambiguity function. The method retains the advantages of pre-weighed ZFFT while at the same time enhances it. By dividing the pre-weighing into cascade, it decreases the sample rate gradually. As a result, no filter with sharp transition band at each step is necessary. The method dominantly reduces the burden of the filtering procedure and accommodates the pre-weighed ZFFT to applications with more strict constraints. Analysis is detailed in this paper and simulations prove that the method markedly improves the efficiency of the pre-weighed ZFFT.