High Accuracy Internal Calibration Scheme And Internal Calibration Signal Processing Technique

The application of synthetic aperture radar(SAR) images has become animportant domain of SAR Technology, along with the national economydevelopment and defense security need.SAR images reflect the electromagnetic scattering characteristics of the targetarea, but also contain a series of radiometric errors affected by atmospherepropagation,radar transmitter and receiver gains, radar antenna gain and so on. SARradiometric calibration techniques are to analyze the synthesis influence of theseerror sources on SAR image, then this influence is compensated in image data andthe quantitative relationship between SAR images and the RCS of the scannedterrain is established. Intemal calibration is an essential constitutor of radiometriccalibration techniques, through internal calibration we can acquire the relative changeof the system gain, so eliminate the influence of the system gain change in SAR image andimprove the SAR image veracity.In this paper, the high accuracy internal calibration technique is mainlydiscussed. An internal calibrator gain control plan based on 'electric bridge principle'is studied, and the design thought and the realization method of the plan areinvestigated, its feasibility is also studied. At last, experiment showed that this plancan control the gain exports stable degree within the range of 0.2dB in a largetemperature range.The final goal of high accuracy SAR calibration is to acquire the gain change ofSAR system from internal calibration data, and then use the result to correct the SARimage, and improve the image veracity. In his article, the processing method of thecalibration signal is introduced, and how to accomplish the gain adjustment ofSAR image is discussed.