Data preprocessing methods for VLBI applications

The software correlator system (SCS) is a key module of Chinese VLBI (Very Long Baseline Interferometry) Network (CVN). The main tasks of SCS include data pre-processing, fringe-searching, correlation, and phase correction signal extraction. In this paper, we propose four approaches for high-speed VLBI data preprocessing on the universal PC-server platform, namely sliding window based time decoding, dynamic lookup-table scheme, squeeze strategy and data synchronization. The experiment results achieved a very small latency especially when the data rate was greater than 256Mbps per station.