Using a Radio-Frequency System on a Chip in the Development of a Phased Radio Array for the Bustling Universe Radio Survey Telescope in Taiwan

The Bustling Universe Radio Survey Telescope in Taiwan (BURSTT) employs the Xilinx ZCU216 radio-frequency system on a chip (RFSoC) field-programmable gate array (FPGA) board as its digital backend. In this study, we used a firmware library available on an online community (called Collaboration for Astronomy Signal Processing and Electronics Research) for hardware implementation. The FPGA board used in the BURSTT accommodates 16-channel analog-to-digital inputs, samples data at 1600 MHz, and has a bandwidth of 800 MHz. Each of the 16 signal inputs is processed independently through a polyphase filter bank followed by the fast Fourier transform. After frequency-domain data processing, the data from all 16 channels are aggregated and sent to a computer server through a 100-Gbps Ethernet for cross-correlation and beamforming calculations. Phase alignment, which is key to the success of radio telescopes, was verified through cross-correlation tests for the same device and between different devices. Phase closure was successfully achieved for three inputs in two devices, which indicated system readiness. An optimal power input level, which is crucial for achieving optimal system performance, was identified. The successful acquisition of spectra from 16 onsite inputs confirmed the applicability of the RFSoC chip in phased systems with a single device or multiple devices.