Contour modulation is a technique in which a phase-modulated signal waveform and amplifier output impedance work together to maintain higher efficiency over a sizable output power back-off.

In this paper, a PD radar signal is researched, which is modulated by randomly staggered pulse sequence whose phase is also modulated by random binary-phase code.

The sound signal is Doppler FM modulated based on the analysis of the moving track of the original source, and then phase modulated according to the interaural time difference.