Construction of waveform library in cognitive radar

Based on the thoughts of cognitive radar, Fractional Fourier Transform (FrFT) is used to generate a rotatable waveform libraries of Frank coded/Barker coded waveform in this paper. Then, the ambiguity function is used to analyze the delay resolution, Doppler resolution, delay side-lobe level, and Doppler side-lobe level of the waveform libraries and orthogonality of them is also analyzed. Furthermore, we proved theoretically that there is a fixed coordinate transformation between the waveforms of library and its origin waveform. Therefore, the Cramér-Rao low bound (CRLB) of motion parameters can be computed easily using the waveforms of the libraries, which facilitate the subsequent waveform scheduled work. Simulation results show that the library waveforms can reduce delay resolution to satisfy the different situations and can bring significant benefits for delay resolution, orthogonality and reuse interval.