D2P
Delay-Doppler Phase-monopulse Radar

The Delay-Doppler Phase-monopulse (D2P) Radar is an airborne radar altimeter developed by Johns Hopkins University Applied Physics Laboratory (JHU/APL). It was designed to demonstrate improvements in satellite radar altimetry and to reduce risks for future flight programs. It uses delay/Doppler and phase-monopulse radar techniques to measure the distance between the altimeter and the surface. It operates at 13.9 MHz and altitudes from 300 to 12000 meters. At a flight altitude of 6000 meters, D2P has a Doppler bin separation of 25 meters. D2P has been used to measure sea ice elevation and snow depth.