RE: Connectivity issues in damp/wet weather

AmbystomaLabs — Tue, 05 Dec 2017 19:13:09 GMT

For starters you should get someone on your team familiar with RF development.

But here is the short list of things you need to check:

Running off the internal RC is an untenable idea at best. RF needs ppm accuracy not percentage accuracy. You need to key up the transmitter on a channel and check channel accuracy over your temp range with a spectrum analyzer on an accurate reference. If you identify something is wrong with the external 16MHz crystal then it must be fixed.
You need to verify your field strength at 1 meter. Easiest way to check this is beacon app on nRF and sniffer app on smartphone. Your design should be at least as good as the DK. This should always be done with the device in the final housing. If it's not right then go back to the bench with the VNA and get it right.
Water is massively lossy at 2.4GHz and highly reflective due to its high value for Er. If you are letting water get into your device it will detune the entire thing and will only be exacerbated by failures in tuning the RF properly. Also, long term you may have issues with the various types of corrosion that affect circuits with static DC voltages. There are conformal coatings but none that I know of with low loss at 2.4GHz.