D2P

The D2P (Dual-Doppler Precision) is an airborne radar altimeter developed in 1998 at the Johns Hopkins University Applied Physics Laboratory (JHU/APL). Operating in the Ku band (13.9 GHz), it was designed to demonstrate improvements in satellite radar altimetry and mitigate risks for future flight programs. The system transmits with intrapulse linear frequency modulation, utilizing two antennas, each measuring 15 cm by 30 cm, with half-power beam widths of 8° (cross-track) and 4° (along-track). Deployed in the bomb bay of a Lockheed P-3 Orion, the D2P system performed Doppler and phase monopulse processing in a laboratory setting, requiring complex calculations for earth curvature correction, flight altitude, terrain slope, and vertical velocity to ensure precise timing and spatial alignment of averaged waveforms. Its initial test flights occurred on March 30 and April 3, 2000.

radartutorial.eu: https://www.radartutorial.eu/19.kartei/08.airborne2/karte007.en.html