A high-speed algorithm for mapping 2-D ambiguity surfaces

The incremented sectionalized Fourier Transform (SFT) is equivalent to basebanding, filtering, and sampling a narrowband signal in the time domain. Spectral windowing is employed to control the pass-band and leakage characteristics of the resulting filter. The ambiguity kernel function and time-shifted SFT´s are exploited to map the 2-D cross-coherence between signals. Mapping in the Doppler dimension is expedited through use of the DFT algorithm. The resulting error is tolerable when the time-bandwidth product of the process is less than the inverse of the maximum Doppler ratio employed. The resultant algorithm has proven successful in real-time underwater acoustic applications.