A new digital backend for the Mexican array radio telescope

Abstract

The Mexican Radio Telescope (MEXART) is a regular aperture array consisting of 4096 full wavelength dipoles whose primary scientific objective is to carry out interplanetary scintillation observations of solar wind disturbances, located in the state of Michoacan in Mexico. The current system uses a Butler Matrix to generate 16 fixed beams, however calibration of the instrument is a problematic issue, resulting in a loss in sensitivity which is impeding the telescope from reaching its potential. In order to improve the performance of the telescope the RF system is going to be converted to a digital one. Signals from the receiving elements, after undergoing conditioning, are transported to a digital backend consisting of FPGA-based digital boards which perform digitisation, channelization and packetization of the channelized data. The beams are then generated on a GPU implementation of a frequency domain beamforming running on a compute server. The antenna signals will routinely be calibrated using transits of strong calibrator sources. This paper presents the design and implementation of the new digital backend, which is planned on being deployed in summer 2019.