GHASP: a Galileo HAS parser

Abstract

Galileo High Accuracy Service (HAS) corrections are broadcast through the E6B signal using a high-parity vertical Reed-Solomon encoding scheme, which reduces message recovery time and improves transmission reliability. To recover HAS corrections, it is thus necessary to invert the encoding process and interpret the decoded bits. In order to foster HAS adoption and facilitate experimentation with HAS corrections, a Galileo HAS Parser (GHASP) has been developed. GHASP is available open-source and supports different input data types from different receiver manufacturers. Decoded corrections are provided in Comma-Separated Values files, which can be directly loaded using common data-science languages. In this way, corrections are readily available and can be used not only for Precise Point Positioning (PPP) applications but also for scientific analysis such as clock characterization using the Allan Deviation.

Assessing the High-Accuracy Service at High Latitudes

“…Several E6-B pages need to be combined in order to extract the actual HAS corrections. This operation is performed using the GHASP software v 1.0 [3,4] developed by the authors. GHASP supports several input formats and is able to convert messages collected using E6-B capable receivers into actual corrections.…”

“…The station features a multiconstellation Septentrio PolaRx5S receiver connected to a choke-ring antenna. The binary files provided by the receiver are processed using an in-house developed decoder, denoted as Galileo HAS Parser (GHASP) [3,4], which is able to retrieve HAS corrections from the Galileo E6-B signal pages collected by the Septentrio PolaRx5S receiver. The corrections were then applied to the broadcast orbits and clocks to obtain precise satellite positions and clock offsets.…”