A Python/CuPy Software Correlator for QUEST: Real-Time Performance and Initial Imaging

TL;DR

This paper introduces a Python/CuPy FX software correlator for small radio interferometers, demonstrating real-time processing, calibration, and imaging capabilities on a GPU for the QUEST telescope.

Contribution

It presents a GPU-accelerated, integrated software pipeline for real-time correlation, calibration, and imaging in small radio interferometer arrays.

Findings

Achieves 1.51 GB/s throughput on NVIDIA RTX 4090D GPU for real-time operation.

Calibrated visibilities produce a clean image of Cassiopeia A with reduced background fluctuations.

Demonstrates suitability for array commissioning and initial imaging on QUEST.

Abstract

We present a Python/CuPy FX software correlator for small radio interferometer arrays and evaluate it on QUEST (Qilu University Explorer Survey Telescope). The system combines multi-threaded data ingest, pinned-memory host-device transfers, GPU-accelerated correlation, Polyphase Filter Bank channelization, MAD-based RFI flagging, and delay/phase calibration in a single workflow aimed at array commissioning. On a single NVIDIA RTX 4090D GPU, the implementation reaches a peak throughput of 1.51 GB/s, which is sufficient for real-time operation in the four-antenna mode tested here. After calibration, the visibility phase across a clean 1.32-1.38 GHz band is flattened to a residual scatter of a few degrees. Using the calibrated visibilities, we form a four-antenna synthesis image of Cassiopeia A; the CLEANed image recovers a compact source at the phase center and reduces image-domain background fluctuations from order 0.1 to a few 0.01 Jy/beam. These results indicate that the software is suitable for small-array commissioning and initial synthesis imaging on QUEST. A GNSS-based beam measurement is included as a supporting commissioning check.