Measuring Velocity For Synthetic Aperture Radar Applications

Greg Johnson

Abstract:	Synthetic Aperature Radar (SAR) requires very precise velocity and time measurements in order to produce a quality radar image. Not only does the velocity solution need to be accurate to 2 cm/s, it also needs to be sampled at a high rate, > 100 Hz. Also, the velocity needs to be measured at the radar aperture arm, which is not the same as the velocity of the aircraft platform. GPS can be used to provide the required velocity accuracy, however velocity based of GPS alone has some shortcomings: 1) GPS is subject to second and third order tracking loop errors during dynamics, 2) GPS low noise measurements cannot be measured at the sampling rate required, and 3) the GPS antenna cannot be placed on the radar aperature arm. In order to achieve this high accuracy velocity solution, high-end inertial systems have previously been used on the aperture arms. This paper shows a method for measuring high rate accurate velocity using the GPS antenna mounted on the aircraft platform, and low-end inertial systems mounted on the aperture arm. Both simulation and field results are shown.
Published in:	Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999) September 14 - 17, 1999 Nashville, TN
Pages:	1099 - 1106
Cite this article:	Johnson, Greg, "Measuring Velocity For Synthetic Aperture Radar Applications," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 1099-1106.
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