meshtastic-firmware/docs/radio-settings.md

Radio settings

We use the same channel maps as LoRaWAN (though this is not LoRaWAN).

See this site for more information.

LoRaWAN Europe Frequency Band

The maximum power allowed is +14dBM.

433 MHz

There are eight channels defined with a 0.2 MHz gap between them. Channel zero starts at 433.175 MHz

870 MHz

There are eight channels defined with a 0.3 MHz gap between them. Channel zero starts at 865.20 MHz

LoRaWAN for North America

LoRaWAN defines 64, 125 kHz channels from 902.3 to 914.9 MHz increments.

The maximum output power for North America is +30 dBM.

The band is from 902 to 928 MHz. It mentions channel number and its respective channel frequency. All the 13 channels are separated by 2.16 MHz with respect to the adjacent channels.
Channel zero starts at 903.08 MHz center frequency.