With @perky tip of raising RSSI threshold I was able to communicate between two nodes with AFC and without frequency calibration and between -20ºC and 60ºC. All the non default parameters were the following:
radio.writeReg(0x03,0x68); //RegBitrateMsb 1200 bps
radio.writeReg(0x04,0x2b); //RegBitrateLsb
radio.writeReg(0x05,0x00); //RegFdevMsb 2000 Hz
radio.writeReg(0x06,0x21); //RegFdevLsb
radio.writeReg(0x19,0x56); //RegRxBw 5kHz Bw
radio.writeReg(0x18,0x08); //RegLna register
radio.writeReg(0x1a,0x4b); //RegAfcBw 50kHz Bw
radio.writeReg(0x1e,0x0C); //AfcAutoClearOn, AfcAutoOn
radio.writeReg(0x29,210); //RSSI Threshold = 105dBm
I'm a bit worried of two things:
- I'm using a very large bandwidth for the AFC (50kHz), so lots of noise will be used for the AFC.I started by using a bandwidth of 25kHz but when I heated one of the nodes to 60ºC I had to raise the bandwidth otherwise there were no communication.
- These two nodes have a frequency difference of about 4kHz but there are others with about 8kHz difference, I still don't know if it will work with frequencies so distant.
Best regards
Fernando