A 1024-channel Wideband Digital Subsystem Prototype for Large Aperture Array Radio Telescope

The new generation of aperture array radio telescopes need to process analogue signals from thousands of antennas, including channelization, correlation, and digital beamforming. The huge amount of raw data poses a great challenge to the processing capability of digital processing system. For 400 MHz bandwidth observation signal fed by 1024 antennas, the digital system should be able to process and exchange a real-time data stream of 3.88 Tbps. A 1024-channel digital subsystem prototype developed, which uses Field Programmable Gate Array (FPGA) transceivers to implement direct, passive, high-speed serial connections between 16 Chinese Tile Processing Modules (CTPM) in one sub-rack and between different sub-racks, standard 10 Gbit/s Ethernet links are used to transfer data to Graphics Processing Unit (GPU) nodes. The digital sub-system can be flexibly customized and expanded to enable different configurations for 16~1024 and 1024*N analogue inputs. Preliminary experimental results such as channel response and channel correction showed that the prototype system has good channel-to-channel consistency and stability, which is suitable for large-scale aperture array applications.