OK, so we have a number of high quality Vaisala HMT333 temperature sensors at various geographical locations (solar/battery powered). At the moment a volunteer observer goes to the site, takes manual readings from the instrument, goes back and then submits these readings to the Met Office Weather Observations Website (WoW).
It would be nice to collect this data automatically and more frequently but also provide a nice little display for the observer in their own home. The prototype I built uses a Raspberry Pi4 and the official LCD touchscreen - really nice LCD case from https://smarticase.com. To get the data from the sensor to the PI I’m using two Campbell Scientific RF422 spread spectrum radio units that easily have a range of 1-2 KM and only use tiny amounts of power.
The display unit connects to the observers home WiFi and transmits data to WoW every 10 minutes. I had to incorporate a way for the local observer to enter their WoW account details and calibration coefficients for the particular sensor in use. They also get a warning when the sensor is due for recalibration and a warning is also produced if no data has been received after a certain time period.
I based the unit on the Balena Dash project but incorporated a Python Flask web application container to deliver the main display and settings pages. Separate containers are used for dealing with the sensor data collection and WoW transmissions, communications between the containers is via http.
Of course you could just use a data unit next to the sensor without a display, but then we would be out of range of WiFi, have to consider power consumption and wouldn’t be able to give the observer a nice little display. You could give them access to a web page/dashboard, but a lot of people don’t want to have to use their phone or computer, they like just being able to glance up at a stand alone display. I suppose that’s why most home weather stations come with a standalone display unit.
Anyway it all seems to be working very well and didn’t take so long to develop thanks to Balena’s technologies. Next stage is to put a few prototypes out in the field for an extended test period and to get some feedback from the observers. Things can move quite slowly in large organisations but it’s looking promising at the moment. Here’s some photos (the WoW account info are just placeholder examples!)