Record and Playback System for GNSS: What You Need to Know for Successful Testing

Iurie Ilie, Rachid Hini, Jean-Serge Cardinal, Peter Blood, Dominique Fortin

Abstract:	Record and playback (RP) systems are increasingly popular in GNSS receivers’ test and validation process. This popularity is mainly due to the capabilities of the RP to re-generate previously recorded live signals with high fidelity and in a repeatable way. Currently such systems are usually used for mass-market receiver testing but their usage for high-grade GNSS receiver testing is somewhat new and explorative. This paper describes the step-by-step signal flow inside the wideband multi-channel/multi-frequency RP system by following the signal from the RF input to the RF output. In spite of the fact that the RP is similar to GNSS simulator, the first differs in principle from the simulators. Whilst the simulator emulates GNSS signals as viewed by a GNSS receiver, the RP is effectively placed between the source of the signals (e.g. satellites + interferences) and GNSS receiver. For this reason, the ideal RP system should be transparent for capturing and reproducing these signals by the tested receiver, ideally with no degradation of signal quality. In practice, the impairments introduced by the RP system have to be negligible, at least for main parameters that affect signal distortion and noise. As the RP is by definition is always between the signal source and the GNSS receiver, the criteria for system impairments are defined by the GNSS receiver under test. As the GNSS receiver plays the role of the independent observer in the RP processing, one can assume that the requirements to the PR performances will be defined by the quality of the receiver’s raw measurements (or the performances of the tested unit). Comparison between the raw data taken live and raw data computed in presence of the RP is a key approach for RP evaluation for a given GNSS receiver to test. The analysis of the signal flows inside the RP shows how the RP parameters are related to the distortion of the mentioned raw data. The test results show that with optimal configuration of the wideband multi-channel RP system, the signal degradation, as based on GNSS receiver measurements, is acceptable for most of the receivers’ applications.
Published in:	Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011) September 20 - 23, 2011 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	2009 - 2021
Cite this article:	Ilie, Iurie, Hini, Rachid, Cardinal, Jean-Serge, Blood, Peter, Fortin, Dominique, "Record and Playback System for GNSS: What You Need to Know for Successful Testing," Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011), Portland, OR, September 2011, pp. 2009-2021.
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