Space/time/frequency methods in adaptive radar - New Jersey ...

50to be 15.4 dB. In the case of the WVD, the window was set to K=64 points. Thetarget's relative velocity was estimated to be 7.1 meters/sec. The contour plot forthe output of the WVD is shown in Figure 2.24. In the case of the STFT, a 64 pointhamming window was utilized. The target's relative velocity was estimated to be7.2 meters/sec. The contour plot for the output in the case of the STFT is shownin Figure 2.25. For the case of the Gabor expansion, the target's relative velocitywas estimated to be 6.5 meters/sec using a 32x16 TF grid oversampled by 4. Thecontour plot for the output in the case of the Gabor expansion is shown in Figure 2.26.Finally, for the case of the scalogram (CWT), the target's relative was estimated tobe 7.4 meters/sec. The contour plot for the scalogram is shown in Figure 2.27. Ascan be seen from the estimated relative velocities, the numerical results from thefour techniques are very similar, however, the representation of the data is not. Inour scenario, the contour plot of the WVD provides the representation with the mostsharply defined chirp characteristic. This is partially due to the particular windowsize that was used in the transforms and the specific transformed signal. The chirpcharacteristics of the moving target for the STFT, the Gabor expansion, and thescalogram are not as obvious but are also apparent. In our simulations, a gaussianfunction was used with the CWT. If a chirp had been used in some form with theCWT as a basis function, the results for the CWT may have improved.2.7.1 Another Chirp in the SignalA second chirp was added to the SAR signal containing the moving target at asignal level that was 5 dB higher that the original signal. This level was calculatedby comparing the energy contained in the added signal and the original SAR image.After transforming the combination of this new signal into a TF representation, amask was created that nulled the areas of the transform domain above a certainlevel for each particular transform. The relative velocity of the remaining chirp was