High-precision measurement of satellite-borne SAR signal bandwidth based on channelized waterfall diagrams

Abstract

Spaceborne SAR has a vast scope of operation that is not restricted by national borders or airspace, so it has been extensively utilized in diverse fields. Due to its non-cooperation, it is difficult for the reconnaissance antenna to obtain the main lobe signal for parameter analysis and working mode identification of the SAR signal, especially when the spaceborne SAR imaging area is far from the location of the reconnaissance antenna. The reconnaissance receiving antenna can only receive a weak SAR signal with a low signal-to-noise ratio, resulting in a significant error in signal parameter measurement and making it unable to fulfill the analysis of its intended operation. Aiming to address the issue of significant measurement errors in spaceborne SAR signal bandwidth parameters under low signal-to-noise ratio conditions, a high-precision measurement method for spaceborne SAR signal bandwidth is proposed. This method is based on a channelized waterfall diagram, which involves accumulating the channelized signal twice to create the chart. The chirp signal on the waterfall chart is then extracted using an image processing technique to accurately measure the signal bandwidth. Additionally, scene simulation under low signal-to-noise ratio conditions is conducted. The simulation results show that even when the signal-to-noise ratio is as low as -10dB, the error in signal bandwidth measurement does not exceed 17%, indicating stable measurement accuracy.