I mounted my Raspberry Pi ADS-B feeder outside my office to avoid damage to the coax as it passes through the window (original 1896 pocket windows with unhelpful storm windows); instead, a USB-C power cable and a network cable are snaked outside, both cheap and easily replaceable.
My main concern has been the RPi‘s temperature: how hot would the RPi get during hot, humid summer days when the enclosure is in direct sunlight? The RPi starts throttling its CPU as the recorded temperature approaches 85˝°C/185°F. Is that enough?
Since late April, I have a cron job run every 5 minutes to capture the current CPU temperature in a date-specific file.
echo "`date -u +"%Y/%m/%d %H:%M:%S"`|`vcgencmd measure_temp`" >> /home/pi/temps/rpi_temps_`date -u +%Y%m%d`.out
The timestamp is UTC and the temperature is celsius. At midnight UTC, an aggregated file with all readings from all days is created and scp’ed to my MacBook.
sed -e "s/|temp=/,/g" temps/rpi_temps_*.out | sed -e "s/'C//g" > composite.csv
Below is the graph of the daily min/max CPU temperature. Despite the daily ranges increasing during our recent heatwave, only a single reading above 60°C has been recorded: 60°C: 60.8°C at 3:20pm CDT on July 27, on a miserable day when the high reached 37.8°C/100°F, well below the worrisome 85°C.
The graph of how often each temperature was recorded shows the vast majority below 50°C with a precipitant drop in readings above 50°C.
Despite six weeks of summer remaining, I’m optimistic that the feeder will survive Minnesota summers. Next up: Minnesota winters!
