Full motion compensation for LFM-CW synthetic aperture radar

Small, low-cost, high-resolution SAR systems, such as the Brigham Young University (BYU) muSAR, are made possible by using a linear frequency modulated continuous wave (LFM-CW) signal. SAR processing assumes that the sensor is moving in a straight line at a constant speed, but in actuality a UAV or airplane will deviate, often significantly, from this ideal. This non-ideal motion can seriously degrade the SAR image quality. In a continuous wave system this motion happens during the radar pulse which means that existing motion compensation techniques, which approximate the position as constant over a pulse, are limited for an LFM-CW SAR. In this paper, the LFM-CW SAR signal model is presented and processing algorithms are discussed. The effects of non-ideal motion during the SAR signal are derived and new methods for motion correction are developed which correct for motion during the pulse. These new motion correction algorithms are verified with simulated data and with actual data collected using the BYU muSAR system.