Radar calibration satellite

Radar calibration satellites are orbital satellites used to calibrate ground-based space surveillance radars. There are two types: active and passive.

Passive satellites

Passive calibration satellites are objects of known shape and size.[1] Examples include the Lincoln Calibration Sphere 1 developed by the MIT Lincoln Laboratory. These are generally solid or hollow spheres, since that shape will have the same cross-section regardless of viewing angle, though later passive satellites used wire grid designs.[2] A ground radar calculates the satellite's position using knowledge of the satellite's radar cross section, and this is compared with the satellite's known position and velocity.[3]

Active satellites

Active calibration satellites are equipped with transponders that emit a signal on command. The ground radar station submits a transmit command and takes a measurement of the satellite's location. The transponder's signal is received by a radar receiver and combined with the satellite's ephemeris data to calculate the satellite's actual position, and this is then compared with the position calculated by the radar measurement in order to measure the radar's accuracy.[4] Examples include the SURCAL series developed by the Naval Research Laboratory and RADCAL,[5].

Further reading
  • Using Satellites for Radar Performance Monitoring and Calibration (PDF) (Report). Secretariat, Range Commanders Council, U.S. Army White Sands Missile Range. March 1995.

References
  1. Mochan, J; Stophel, R. A. (1968). "Dynamic Calibration of Space Object Tracking Systems". The Space Congress Proceedings. 1: 1.1–1. Retrieved 12 October 2021.
  2. Sui, Yun; Fu, Haiyang; Xu, Feng (December 2018). "C-Band ISAR Imaging for the Precision Expandable Radar Calibration Sphere". 2018 12th International Symposium on Antennas, Propagation and EM Theory (ISAPE). pp. 1–4. doi:10.1109/ISAPE.2018.8634235. ISBN 978-1-5386-7302-7. S2CID 59620160. Retrieved 14 July 2022.
  3. Bernhardt, Paul A.; Siefring, Carl L.; Thomason, Joe F.; Rodriquez, Serafin P.; Nicholas, Andrew C.; Koss, Steven M.; Nurnberger, Mike; Hoberman, Chuck; Davis, Matthew; Hysell, David L.; Kelley, Michael C. (February 2008). "Design and applications of a versatile HF radar calibration target in low Earth orbit: HF RADAR CALIBRATION TARGET IN ORBIT". Radio Science. 43 (1). doi:10.1029/2007RS003692.
  4. "Ho'oponopono - eoPortal Directory - Satellite Missions". directory.eoportal.org. Retrieved 14 July 2022.
  5. Lawrence, Taylor (24 July 2013). "Satellite's operation time exceeds expectations". Kirtland Air Force Base. 377th Air Base Wing Public Affairs. Retrieved 18 October 2021.
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