Our participation in LISA Pathfinder has given us the big chance to develop technology considered mission critical. Regarding software, in particular, our computer engineers have developed the embedded software executed in Data Management Unit.
This software consists in two parts:
- Boot software: In charge of booting the system, setting up the communications link with the OBC and managing the application’s code (that is enabling ground patchings for Application). Built from scratch by our engineers, this little piece is a reduced operating system whose robustness is critical for the success of the activities.
- Application software: Main core. In charge of processing data from several subsystems and provide scientific results to OnBoard-Computer and to ground. Using a real-time operating system (RTEMS), main tasks run at 100hz.
Around the embedded software, a large number of tools to help the develop itself have been implemented. These tools finally have been integrated in a complete Software Verification Framework, which enables the test and verification of BSW and ASW. The SVF has a OnBoard computer simulator along Subsystems (Laser, Inertial-Sensor, Phasemeter, Caging and Charge mechanism) simulators.
The Whole Data Management Activity can be tested/used without the needed of any real hardware.In order to have a complete DMU environment without any physical hardware, the necessary layers to be attached to TSIM simulator have been developed.
The knowledge of our engineers regarding software developing, involves:
- Realtime embedded sofwtare
- Aerospace Communication protocols (MIL-STD-1553)
- FPGA control.
- Testing: Unit test along high level tests needed for official Software qualification.
- ECSS-E40-Part 1B standard
Our technological work is focused on the design and development of low frequency/low noise systems to measure magnetic field and temperature for LISA and LISA Pathfinder missions.
Low noise measurements at the sub-milli-Hertz frequency have been carried out using different noise reduction techniques in the signal conditioning circuit like Lock-in Amplification, Ratiometric Conversion, Dithering and Flipping. These methods has been widely used in high sensitivity measurements, however, it has not been assessed in the milli-Hertz region. The reasons to perform these techniques are:
- Significant improvement in the 1/f noise within the desired bandwidth
- To reduce thermal drifts due to the self-heating or external environments
- Mitigation of the Analog-to-digital converter (ADC) errors
- Offset extraction
- To enhance the sensitive performance of the sensor
Nowadays, we are achieving the lowest noise measurements in the frequency range of the milli-Hertz using Anisotropic magnetoresistance (AMR) published so far. This technology is being studied to develop criteria for the best choice of magnetic sensor for LISA mission, motivating their use in Space.