BirdNET-Pi - Hardware considerations
RTC
Raspberry Pis don’t have a real time clock(RTC) so they lose date and time if not connected to network on power loss. You can set this manually or there are add on components that provide a RTC.
Microphones etc
TRRS omni directional is ideal for a sampling application like I was doing, but a shotgun mic worked and had better detections - just not all directions.
I was not able to get the exact model of mic that was most recommended, they were just not available. I did find a closely related model that was TRS rather than TRRS, so I purchased a TRS-TRRS adapter and hoped it would work - it didn’t. After considerable fiddling, I finally plugged the mic and sound card into something else. They worked with everything I plugged them into - phone, desktop, laptop, just not the RPI. It only took me 3 days to figure that out and to track down another functional mic. This one worked without a hitch. I still don’t know why that first mic refused to work with the RPI.
Edutige EIM-001 - TRRS - TRS version doesn’t work with the Pi, even with adapter https://www.thomannmusic.com/edutige_eim_001.htm
Compounding the mic problems, the RPI didn’t always assign the address to the sound card the same way. There are a couple of commands that can be used to sort this out but the best practice seems to be that once you get the addressing to work - don’t unplug the sound card, or at least plug it into the same port every time. I was using two USB dongles for a wireless keyboard and mouse, they may have also contributed to the issue.
In the end I used either a shotgun mic VXR10 or an omnidirectional MA2010 - both by MOVO. Incidentally, I had 2 different shotgun mics get wet and quit working. After assuming they were dead and throwing them in a corner, I went back and tested them after several days - both are still working fine after drying out.
I purchased a TRRS cable to connect mic to sound card and allow flexibility in deployment - a 3 ft cable seems to work pretty well.
I went with the recommended USB sound card - UGREEN - I’ve not had any issues with either of the ones I have.
Case selection
There are a few things to consider when choosing a case. Heat dissipation is an issue, particularly if deployment will be in the field. If the device has a reliable power source (AC), a fan is always an option but a case with a good passive heat sink design might be sufficient. The Flirc case that came in our kit seems to be a pretty solid passive design. It worked well as long as a HAT was not installed. If you intend to install a fan or a power management HAT you’ll need a case that will accommodate that.
To accommodate a hat I tried a really simple case by Geekworm that was only $6.00. It consists of two pieces of acrylic with some screws and standoffs. Basically just a top and bottom, but since I didn’t have a fan, that provides a chance for lots of airflow through the device, particularly if it was “mounted” on its side. So I just made sure it was laying sideways when I put it in its exclosure.
https://www.amazon.com/Raspberry-Universal-Protective-Geekworm-Enclosure/dp/B074T7D1V5