A Study of a Pulsar Observation System Using the Coherent De-Dispersion Technique

The radio astronomy group of the Yunnan Observatories (YNAO) has designed a data-collection terminal with digital baseband sampling by using a ROACH2 FPGA platform purchased from the CASPER of the Berkeley University.The terminal has an input bandwidth of 512MHz evenly divided into 128 channels.It samples data in 8bit with input data collected in a dual-polarization mode.Massive amounts of collected data are transmitted to the processing unit through a 10 Gigabit SFP+ Ethernet port.The subsequent data-processing steps include ROACH2 data decoding, coherent de-dispersion, polarization calculation, and periodic folding using scripts to call the DSPSR package.The data processing results in output observation data in the PSRFITS format.Compared to previous VLBI terminal systems this system shows advantages in the observation mode, data processing methods, computing efficiency, flexibility of output data, and etc.