A Digital-Receiver for the Murchison Widefield Array

TL;DR

This paper presents the design and implementation of an FPGA-based digital-receiver for the Murchison Widefield Array, enabling digitization, channelization, and transmission of signals from 128 antenna tiles for radio astronomy observations.

Contribution

It introduces a novel digital-receiver system tailored for the MWA, integrating multiple functions including digitization, power measurement, interference detection, and control, with plans for future improvements.

Findings

Successfully processed signals from 128 tiles across 80-300 MHz

Achieved real-time power measurement and interference detection

System is ready for deployment and further enhancements

Abstract

An FPGA-based digital-receiver has been developed for a low-frequency imaging radio interferometer, the Murchison Widefield Array (MWA). The MWA, located at the Murchison Radio-astronomy Observatory (MRO) in Western Australia, consists of 128 dual-polarized aperture-array elements (tiles) operating between 80 and 300\,MHz, with a total processed bandwidth of 30.72 MHz for each polarization. Radio-frequency signals from the tiles are amplified and band limited using analog signal conditioning units; sampled and channelized by digital-receivers. The signals from eight tiles are processed by a single digital-receiver, thus requiring 16 digital-receivers for the MWA. The main function of the digital-receivers is to digitize the broad-band signals from each tile, channelize them to form the sky-band, and transport it through optical fibers to a centrally located correlator for further processing. The digital-receiver firmware also implements functions to measure the signal power, perform power equalization across the band, detect interference-like events, and invoke diagnostic modes. The digital-receiver is controlled by high-level programs running on a single-board-computer. This paper presents the digital-receiver design, implementation, current status, and plans for future enhancements.