A new waveform utilizing Costas sequence and interpulse frequency hopping (FH) can be used as a good high range resolution radar signal. The signal processing using inverse discrete Fourier transform (IDFT) in the interpulse Costas FH radar was studied. The principle of the interpulse Costas FH radar signal without the delay Doppler coupling was analyzed. The influence of target motion on synthetic range profile was discussed and simulated.