A real-time software backend for the GMRT

TL;DR

This paper presents a real-time, software-based backend system for the GMRT radio telescope, enabling flexible, high-resolution data processing and interference rejection using off-the-shelf components and optimized parallel computing.

Contribution

It introduces the first real-time software backend for an intermediate-sized radio array, demonstrating its design, implementation, and initial successful observations.

Findings

Successful real-time operation with 32 antennas and 33 MHz bandwidth

Enhanced flexibility in data resolution and interference rejection

Rapid development and deployment of a sophisticated backend system

Abstract

The new era of software signal processing has a large impact on radio astronomy instrumentation. Our design and implementation of a 32 antennae, 33 MHz, dual polarization, fully real-time software backend for the GMRT, using only off-the-shelf components, is an example of this. We have built a correlator and a beamformer, using PCI-based ADC cards and a Linux cluster of 48 nodes with dual gigabit inter-node connectivity for real-time data transfer requirements. The highly optimized compute pipeline uses cache efficient, multi-threaded parallel code, with the aid of vectorized processing. This backend allows flexibility in final time and frequency resolutions, and the ability to implement algorithms for radio frequency interference rejection. Our approach has allowed relatively rapid development of a fairly sophisticated and flexible backend receiver system for the GMRT, which will greatly enhance the productivity of the telescope. In this paper we describe some of the first lights using this software processing pipeline. We believe this is the first instance of such a real-time observatory backend for an intermediate sized array like the GMRT.