FMCW(Frequency Modulated Continuous Wave)radar with chirp sequence waveform is widely used in automotive applications.To resolve Doppler ambiguities in multi-target environment

we modify the classical chirp sequence waveform by adding a period of time delay before each chirp with even sequence number.The modified waveform is essentially a combination of two classical chirp sequences

one is composed of all the chirps with even sequence numbers

and the other one is composed of all the chirps with odd sequence numbers.The time delays in the modified waveform generate a phase difference between two beat signal groups corresponding to the two chirp sequences.Doppler ambiguities are resolved by the phase difference.Theoretical analysis and simulation results verify the effectiveness of the modified waveform.