Low velocity target detection based on time-frequency image for high frequency ground wave radar

The Doppler spectral broadening resulted from non-stationary movement of target and radio-frequency interference will decrease the veracity of target detection by high frequency ground wave (HFGW) radar. By displaying the change of signal energy on two dimensional time-frequency images based on time-frequency analysis, a new mathematical morphology method to distinguish target from nonlinear time-frequency curves is presented. The analyzed results from the measured data verify that with this new method the target can be detected correctly from wide Doppler spectrum.