Speaker
Description
We present a dedicated spectrometer and its corresponding firmware developed for the BINGO radio telescope—the first large-scale project in South America designed for 21-cm intensity mapping of neutral hydrogen (HI) across cosmological distances. Built on the CASPER FPGA-based SKARAB platform, the firmware performs real-time power spectrum analysis over the 980–1260 MHz band, supporting cosmological studies in the redshift range $0.127 \leq z \leq 0.449$, with the spectral resolution and data throughput needed for long-duration surveys.
Adapted to BINGO’s “single-dish, many-horns” configuration, the firmware processes real-time data from 28 horn antennas through SKARAB ADC modules, each digitizing four RF inputs—two orthogonal polarizations and two ColFET reference loads—while employing Dicke switching to mitigate gain fluctuations. The digital signal processing chain consists of pre-processing, FFT-based channelization, and Stokes parameter computation, with decimation and accumulation parameters optimized for the telescope’s observing strategy. In the pre-processing stage, a decimation factor of 8 narrows the effective bandwidth to 375 MHz, matching the BINGO observation band. A 32-bit, 8,192-point Polyphase Filter Bank (PFB) and FFT pipeline provides a spectral resolution of 45.7 kHz every 21.8 $\mu$s, ensuring superior channel isolation and reduced spectral leakage. Resulting spectra are transmitted over a high-speed QSFp+ 40 GbE Ethernet link and stored in FITS format, with an accumulation length of 45,776 producing around one averaged spectrum per second—equating to 10.8 GB of data per day for each horn.
This design meets BINGO’s needs and can be scaled for future HI mapping experiments around the world.
