Frequency Coordination and Channel Planning

When multiple independent mesh networks coexist in the same geographic area, frequency and channel coordination prevents interference and allows for intentional interconnection where desired.

The 902-928 MHz Band Structure

In the United States, the 902-928 MHz ISM band is 26 MHz wide. LoRa transmissions are narrow (125-500 kHz bandwidth), so many channels can coexist. However, dense networks in the same area can cause packet collisions if they use identical frequencies.

Meshtastic Channel Numbers

Meshtastic calculates its center frequency from a channel number (0-7 by default) and the modem preset bandwidth. With 125 kHz BW, channels are spaced 125 kHz apart.

# Default US center frequency (channel 0, 125 kHz BW):
# 906.875 MHz

# Set channel number via CLI:
meshtastic --set lora.channel_num 3

MeshCore Frequency Selection

MeshCore uses fixed frequency presets. The USA/Canada preset is 910.525 MHz. Networks in the same area using MeshCore should coordinate to avoid using the same frequency if they don't want to interoperate.

Avoiding Interference with Other Users

The 902-928 MHz band is shared with ISM devices, FHSS systems, baby monitors, cordless phones, and other LoRa networks. If you observe high packet error rates that don't correspond to weak signal strength, interference from another source may be the cause. Use an SDR (Software Defined Radio) to scan the band and identify active signals.

Multi-Network Coordination

When two community networks exist in overlapping geographic areas, coordinate:

1. Different channel keys with same frequency — Networks stay logically separate even if they occupy the same frequency. Acceptable for low-traffic networks.
2. Different frequencies + different keys — True RF isolation. No collision possible. Recommended for medium/high-traffic networks within range of each other.
3. Intentional bridging — A dual-radio or dual-channel node that bridges the two networks. Both networks benefit from the other's coverage.

Documentation for Multi-Network Areas

Maintain a local frequency coordination document shared between network operators: