Movesense HR Sensor - Acceleration data noise level at high vs low sample frequency

Question

measured standard deviation of the Acceleration signal from the Movesense HR+ sensor collected by the MS showcase app is the same at 1666Hz sample frequency compared to the 208Hz and even 26Hz SF. Assuming that 1666Hz is fastes sampling possible, one would think that at 8 times lower SF one data point at 208Hz would be the average of 8 collected data samples and hence, would come with sqrt(8) = 2.8 times lower noise. But it is not the case unfortunately. We have started to work on our own data collection app and planned to use lower SF/service for the benefit of having lower data transfer rate and a lower noise level. But we are afraid to have to subscribe the the (highest) 1666Hz service and do the averaging subsequently in the sensor, at a much higher resource cost. Or is there a way to subscribe to a lower SF/service and receive an already averaged sensor signal with lower noise?

Answer 1

The current Movesense firmwares set the accelerometer modes so that the high performance mode is used when samplerate is 416 or higher. This results the sensor being in the "low-power mode" when SR is <= 52 Hz and "normal mode" when samplerate is either 104 or 208 Hz.

Full disclosure: I work for the Movesense team