Once the Galileo IOV satellite platforms are activated and checked out in the LEOP phase, the In-Orbit Test (IOT) campaign begins to assess the performance of the satellites’ navigation payloads.

Control of the satellites is passed to the Oberpfaffenhofen Galileo Control Centre in Germany while their payloads at evaluated at ESA’s ground station at Redu in Belgium, which has been specially equipped for the IOT campaign with specialised antennas for receiving and uplinking signals. Redu has already completed the In-Orbit Test campaign for the first two Galileo satellites.

Redu and Oberpfaffenhofen will remain constantly linked for the duration of the IOT so Redu can receive quasi-real-time telemetry and other supporting information.
Once released from their launcher, the Galileo IOV satellites enter an orbit with a 14-hour orbital period, making them visible from Redu for only limited periods each day, typically ranging from nine to three hours, so activities have to be carefully scheduled.

ESA's Redu station

The IOT ground station is equipped with an L-band receive-only antenna to receive satellite navigation signals, a C-band transmit antenna to send navigation messages to the satellite payload and a UHF transmit antenna for transmitting simulated search and rescue signals to the satellite.

The IOT campaign measures the accuracy and stability of the satellites’ onboard clocks, as well as assessing the quality of the navigation signals. The results gathered during the campaign will set a benchmark throughout the satellites’ operational life and constitute a reference basis for the entire Galileo constellation.

The Redu ground station has already carried out an IOT campaign for GIOVE-B as well as the first two Galileo IOV satellites, and will perform similar IOT activities for further Galileo satellites, as well as being reactivated as needed for follow-up payload measurements or anomaly investigations.