Hello everyone, this is Leo! After a long wait here comes some updates on the magnetometer sensors.
The sensors
Back in April we shipped our boards and cables together with some 3D printed prototypes of the boom structure to Lviv in Ukraine. The SMILE sensors are being manufactured over there by our colleagues. We shipped all the boards over there, so that they can assemble them and make sure the sensors work as intended.
The parts that we shipped to Lviv
In the picture above, you can see all the parts that we shipped to Lviv. The small boards are the breakout boards. They are used to connect the flex cables that go from the boom motherboard to the sensors. The bottom left boards are the SMILE boards. They take in the signals from the sensors and after some signal processing, they send back the actual value of the magnetic field readings to the motherboard.
An important aspect of the experiment is that the two magnetometers are recording data at the same time, in other words they are synched together. This is key to ensure that the readings we get make sense. Also, it makes it easier for the analysis once the experiment has been completed. Some changes had to be made on the SMILE firmware in order to synchronize the two sensors. After some brainstorming, we decided that the easiest solution was to make one of the sensors behave as the main sensor and tell the other sensor when to record.
After a long wait of over three months we got our beloved sensors back from Ukraine! In the picture above you can see on the left the mid-breakout board, and on the right the tip-breakout board with the sensor inside the casing.
The connection test
Right after they arrived, Andreas and I immediately connected all the parts, powered them and proceeded to test them and see if we could get back some data and...
Results of the connection test
They Worked! The values between the two sensors were matching.
After making sure that everything was working we proceeded on the calibration of the sensors.
The calibration of the sensors
In order to calibrate them we had a few options.
Use one sensor already calibrated as reference and adjust the newly arrived ones so that they match the calibrated one.
Go in an open space where we know the magnetic field with high accuracy, such as a park away from buildings and power lines (To avoid interferences).
Use a shielding enclosure and measure the offset of the sensors, assuming that the magnetic field inside the enclosure is close to 0.
The most complicated and time consuming option would be to take the sensors to a proper calibration center where they can control the magnetic field inside of a room. Luckily for us there is exactly what we need close to Uppsala!
The temporary testing boom
Andreas performing a test
Checking that we saved the data successfully
We will perform more calibrations and also test the sensors in the flight configuration and in the proper setup. Hopefully we will also be able to take our sensors on a trip to Uppsala. This was just the start, but it is looking good so far!
Leo
And here are some extra photos!
It is definitely not a potato gun!