Paris, France (ESA), 05 May 2007: Earlier in the first week of May, GIOVE-A successfully transmitted its first navigation message, containing the information needed by user receivers to calculate their position. Prior to send this, the satellite had been broadcasting only the data needed for measuring the receiver-to-satellite distance.
The first Galileo navigation message was created by the navigation signal generator unit on board GIOVE-A, using content prepared by the GIOVE Mission Segment. This week-one navigation message was uplinked to GIOVE-A on 2 May from the Guildford ground station operated by Surrey Satellite Technology Ltd (United Kingdom) and then transmitted from the spacecraft to the users.
The objective of the test was to demonstrate an end-to-end link between the Mission Segment and the user receivers. The navigation message is being generated for demonstration purposes only, no service guarantee is provided.
The complete radio transmission from GIOVE-A carries a navigation signal and a navigation message. The navigation signal contains the information needed to measure the distance from the satellite to the user receiver. The navigation message provides the timing and spacecraft orbit data needed to calculate the time and exact position of the satellite.
One of the main tasks of the GIOVE Mission Segment is the generation of this navigation message. Aside from navigation message generation, the primary tasks of the GIOVE Mission Segment are performance characterisation of the on-board clocks, orbit modelling, and operations planning and telemetry analysis for the navigation payload.
The GIOVE Mission Segment comprises two main elements, a world-wide network of 13 Galileo experimental sensor stations and the GIOVE Processing Centre (GPC) located at ESA’s European Space Research and Technology Centre (ESTEC) in Noordwijk, The Netherlands. The GPC is operated by European Satellite Navigation Industries (ESNIS) – the new name for Galileo Industries.