For the purpose of calibrating the Temperature and Humidy sensors, I have proceeded to use a BM280 connected to an arduino Mega with the Bosch Sensortec library, and compare those values against the Nicla Sense ME with their own filtering algorithm and see how acccurate they are.
I have chosen to use the BM280 initially, before buying commercial devices to compare against. I have intiially asked Puja and the university, but they did not have anything appropriate.
In order to calculate the altitude on the Nicla Sense ME, I have used the hypsometric formula with the temperature and pressure data.
Furthermore, by researching the Bosch Sensortec Forums, I have found out that the scaling for the temperature is wrong at 0.010 and should be changed to 0.008 (available here: https://community.bosch-sensortec.com/t5/MEMS-sensors-forum/Nicla-Sense-ME-Large-Array-Crash/td-p/36117/page/2), although these scaling of 80% may be innacurate as well.
Testing environments:
BM280 - Outside Readings:
BM280 - Inside (Living Room) readings:
Nicla Sense ME - Outside readings:
The following series of graphs with curves represent the average of 5 readings in 4 different places as well as an explanation of the research:
We can see how the orange series representing the Nicla Sense temperature is different from the BM280, it seems that the lower the value the less the game to the point where it reaches a negative difference. So the sensor data may have to be linearized and matched to the current data.
However, I will first have to buy commercial devices, and complete the same research/analysis on calibrated true values.
As the university does not have devices that help with this data, I have ordered 2 devices on Amazon, those that were reviewed with high accuracy:
Alexa Smart Air Quality: Device that keeps track of temperature, humidty, CO2eq in ppm, air quality index and pressure.
Finger Oximeter: This device is used to measure heart rate and oxygen percentage in red blood cells. My sensor is placed on the wrist, but the SpO2 value is more accurate from the finger, so I can map/calibrate the correct finger reading from the Finger Oximeter device, to my "innacurate" SpO2 readings from my sensor.
