Nyan is using 869.525, currently with Meshtastic's “Long Fast”, of 250kHz BW, SF11.

Other users of this frequency include:

• Helium: 869.525 MHz, SF12, 125 kHz BW.
• The Things Network (LoRaWAN) ?

I believe that LoRa on the same frequency but different spreading factor will appear as noise to the other radio.

Went on roof to fit some speculative ferrites and extra power supply caps. Colin noticed a mobile phone sector aerial pointing right at us from a nearby church.

Listening on a hackrf with heltec lora padel antenna, there was a very strong signal around 810MHz.

There was no obvious increase in noise at 869 MHz when powered on the nyan box, suggesting the local power supply and electronics probably not at fault.

The strong signal on 810 MHz went down 20dB when I put the church GSM aerial behind the building. I suspect therefore that inadequate filtering on the LoRa receiver is the problem. Maybe adding a filter would help.