Abstract: The data acquisition system of very long baseline interferometry global observation system(VGOS) has ultra-broad recording bandwidth and ultra-high data rate.The data rate is stable up to 16Gbit/s.Pre-processing such as data playback and analysis is the key step from data acquisition to data correlation.For the domestic VGOS acquisition system,a VGOS baseband data pre-processing system was developed;the metadata and baseband data format of high-speed recorded data were analyzed;the pre-processing modules such as data recording,gathering,de-thread and rechannel were designed and implemented.Through the research and test of the preprocessing system,the methods to improve its efficiency were analyzed.Moreover,the preprocessing system was successfully used to replay and analyze the observation data of international VGOS station,and the interference fringes were successfully obtained through data correlation processing.All of these show that the data pre-processing system can correctly process high-speed data.The average data gathering rate can reach up to 10Gbit/s and the de-thread efficiency can reach to 3.6Gbit/s,which achieves the current goals of ultrawideband and ultra-high speed processing of VGOS observation’s baseband data.

Key words: VGOS, VLBI, baseband data, data pre-processing, data correlation