Edge Collective

Further exploring low-temp behavior

Testing low-temperature fixes we made recently.

Sat 11 Jan 2025 11:06:46 PM EST

Comparison, distance and temperature

Comparing 'pre-upgrade' to 'post-upgrade'

In the below charts, you can see how the distance measurements seem to be impacted.

Note that in December, we were using the 'older' code. The 'upgraded' code was used in January.

Focus on 'post-upgrade'

Now we focus only on the 'upgraded' system. Note that the system seems to register a greater distance when the temperatures are colder ... but that there doesn't seem to be a clear temperature threshold for this behavior.

Perhaps here we are seeing a condensation effect that tends only to occur overnight?

Freezer Test

Sat 18 Jan 2025 06:33:43 PM EST

Placed sensor and transmitter box in freezer overnight. Battery was external.

Data collected in Google Sheet here.
Temperature in freezer overnight. Looks like it takes a while for compressor to kick in to knock freezer temp down to around -15.
Distance measurement in freezer overnight. Distance changed by 1 cm over course of experiment. As temperature decreases, speed of sound decreases, so the sensor will think the object is further away; so a 1 cm increase is explained by lack of temperature compensation; but from the timing, it seems as though the increase happened before the temperature really dropped, so this might simply be 'noise'.

TODO