Methods, systems, and devices for radar signaling are described. In some systems, devices may implement techniques to support coexistence for multiple radar sources using a phase-coded frequency modulated continuous wave waveform. A user equipment (e.g., a vehicle) may select a codeword (e.g., a pattern of parameters) from a codebook and may derive phase code information and waveform shape parameters from values specified in the codeword. The user equipment may apply phase modulation to at least one chirp of a waveform using the indicated phase code. In some cases, the phase-coded frequency modulated continuous wave waveform may resemble nested Zadoff-Chu sequences, where the waveform resembles a Zadoff-Chu sequence and the phase code resembles another Zadoff-Chu sequence. The phase code may support mitigating interference between radar waveforms that use the same slope and frequency offset parameters for chirps overlapping in time.