How does the radar waveform design affect the ability to separate multiple targets at similar ranges?

The radar waveform design directly determines the ability to separate multiple targets at similar ranges through three key parameters: chirp bandwidth (which sets range resolution), chirp duration and number of chirps per frame (which set velocity resolution), and MIMO waveform orthogonality (which sets angular resolution). Range separation requires the targets to be more than delta_R = c/(2B) apart, where B is the chirp bandwidth; at 4 GHz bandwidth this is 3.75 cm. Velocity separation requires a Doppler resolution of delta_v = lambda/(2 x N_chirps x T_chirp), and angular separation requires the targets to be more than one beam width apart. When two targets are at nearly the same range and velocity (like a pedestrian standing next to a parked car), only angular resolution can separate them. But when targets are at the same angle (like two vehicles in the same lane at slightly different distances), only range resolution can distinguish them. The waveform designer must optimize the chirp sequence to simultaneously provide adequate resolution in all three domains. Advanced waveform techniques include interleaved fast and slow chirps (providing both fine range and fine Doppler resolution), frequency-division MIMO (allowing simultaneous TX transmission for faster frame rates), and non-uniform chirp spacing for improved Doppler ambiguity resolution.