Design of a multi-function high-speed digital baseband data acquisition system

A multi-function digital baseband data acquisition system is designed for the sampling, distribution and recording of wide-band multi-channel astronomical signals. The system hires a SNAP2 board as a digital baseband converter to digitize, channelize and packetize the received signal. It can be configured dynamically from a single channel to eight channels with a maximum bandwidth of 4096 MHz. Eight parallel HASHPIPE instances run on four servers, each carrying two NVMe SSD cards, achieving a total continuous write rate of 8 GB s−1. Data are recorded in the standard VDIF file format. The system is deployed on a 25-meter radio telescope to verify its functionality based on pulsar observations. Our results indicate that during the 30-minute observation period, the system achieved zero data loss at a data recording rate of 1 GB s−1 on a single server. The system will serve as a verification platform for testing the functions of the QTT (QiTai radio Telescope) digital backend system. In addition, it can be used as a baseband/VLBI (Very Long Baseline Interferometry) recorder or D-F-engine of correlator/beamformer as well.