High spectral resolution multi-tone Spacecraft Doppler tracking software: Algorithms and implementations

TL;DR

This paper introduces SDtracker, a software for high-precision spacecraft Doppler tracking using VLBI radio telescopes, enabling accurate frequency and phase measurements without prior spacecraft models.

Contribution

The paper presents a novel software package that achieves sub-Hz frequency detection and phase reconstruction for spacecraft signals, validated across multiple deep space missions.

Findings

Achieved sub-Hz frequency detection precision.

Validated software across various deep space missions.

Compatible with standard VLBI data worldwide.

Abstract

We present a software package for single-dish data processing of spacecraft signals observed with VLBI-equipped radio telescopes. The Spacecraft Doppler tracking (SDtracker) software allows one to obtain topocentric frequency detections with a sub-Hz precision, and reconstructed and residual phases of the carrier signal of any spacecraft or landing vehicle at any location in the Solar System. These data products are estimated using the ground-based telescope's highly stable oscillator as a reference, without requiring an a priori model of the spacecraft dynamics nor the downlink transmission carrier frequency. The software has been extensively validated in multiple observing campaigns of various deep space missions and is compatible with the raw sample data acquired by any standard VLBI radio telescope worldwide. In this paper, we report the numerical methodology of SDtracker, the technical operations for deployment and usage, and a summary of use cases and scientific results produced since its initial release.