The continuous growing sophistication and size of GEO spacecraft leads to a large increase of the amount of TM available on board.
Moreover, the improvements in the performances of the data acquisition devices like A/D converters lead to an increase of the accuracy of the data acquired on board and in turn to an increase of the bandwidth necessary to download all the information.
Looking onto the heritage data and lesson learned from troubleshooting and on flight management of GEO satellite, and in the dialogue with usual prime industries, it has been paradoxically pointed out the decrease in the amount of meaningful TM available to satellite operators and the new difficulty for them to exploit all telemetry especially during emergency.
It has been found that:
In the end, the large amount of TM available distracts the operators from the strictly necessary telemetry to be treated during the emergency, and makes operations of the spacecraft overly complex.
The TMU (TeleMetry Unit) is a VHDL Core developed by Thales Alenia Space to acquire and process a set of telemetry channel data with the aim of improving the TM data usefulness and of reducing the amount of data downloaded on ground
The great advantage of the TMU over a standard telemetry unit is that by only reading a “Synthetic Report” (composed by only 5 data words of 16 bit) the SMU can verify that all units monitored by the TMU are in nominal status; since the Synthetic Report can be sampled often, the reaction time in case of a unit fault is drastically shortened.
Also, by only fetching the various Algorithms Processing Reports (only 8 data words of 16 bit) the ground station can have useful information on the units status (such as average values, calibrated readings), reducing the bandwidth needed for telemetry.
Moreover, the TMU can apply an effective compression algorithm on the acquired data.
In case of a unit under monitor becomes faulty, the TMU signals the event by raising an event flag on its Synthetic Report and automatically fills in a detailed Event Report (composed by 15 data words of 16 bit) of the faulty unit at the specific moment of fault.
Therefore the TMU features are:
The TMU (TeleMetry Unit) is a VHDL Core developed by Thales Alenia Space to acquire and process a set of telemetry channel data with the aim of improving the TM data meaning and of reducing the amount of data downloaded on ground.
The TMU implements the following functions:
The project team involved TAS-France and TAS-Italy with task sharing based on respective background and respective competencies.
TAS-F Cannes managed the study and covered mainly the system aspects:
TAS-I Milan performed development and testing of Telemetry Unit :
To test and validate the TMU functions an Electrical Bread Board model (TMU EBB) was developed, supporting all the TMU functionalities.
TMU VHDL code has been designed and implemented onto Electrical Bread Board (EBB) unit.
Unit acceptance has been successfully performed.
Final demonstration was held at ESTEC premises on 1st April 2014.