Sampling Clock Imperfection Analysis for Synthetic Aperture Interferometric Radiometer

In this paper, a nontrivial sampling clock imperfection analysis is presented for Synthetic Aperture Interferometric Radiometers (SAIR). Sampling clock determines the edges at which analog radiometric demodulated signal are digitized for digital correlation, and its jitter and skew could lead to SAIR performance degradations. Firstly, the jitter and skew contributions to visibility uncertainty degradation is analyzed by SAIR correlation principles. Secondly, clock jitter effects on Analog-to-Digital Converter (ADC) SNR is demonstrated, and this effect is quantitatively evaluated by Time Interval Error (TIE) jitter. The jitter simulation method by Phase Noise Integration (PNI) is also proposed. Thirdly, the Phase Synchronization Method (PCM) is presented to decrease the clock skews between correlation channel pairs to improve decorrelation effects. The experimental verifications for clock jitter and skews are conducted on the BHU-2DU SAIR instrument, and the contributions of this paper are concluded. This paper has proposed nontrivial imperfection analysis for SAIR sampling clock, and the conclusions could be used for SAIR and polarimetric radiometer digital correlation designs. Key-Words: Samping Clock, Jitter, Skew, SAIR, Visibility Uncertainty, SNR, TIE Jitter