Meshtastic Channel Number Selection Guide

Meshtastic's channel number setting controls the exact center frequency of LoRa transmissions within the regulatory band. Choosing the right channel number can reduce interference with other users and allow multiple independent networks to coexist peacefully.

How Channel Numbers Work

Meshtastic calculates the center frequency from the channel number, modem preset, and region:

# For US region with LongFast (125 kHz BW):
# Base frequency: 902.0 MHz
# Channel spacing: 0.125 MHz (125 kHz)
# Center frequency = Base + (channel_num * spacing) + offset

# Channel 0: 906.875 MHz (default)
# Channel 1: 907.000 MHz
# Channel 2: 907.125 MHz
# ...
# Channel 7: 907.875 MHz

# For MediumFast (250 kHz BW):
# Channel spacing: 0.25 MHz
# Channel 0: 906.875 MHz
# Channel 1: 907.125 MHz

Why Change the Default Channel 0?

Most Meshtastic nodes ship with channel 0 as default. If your area has significant Meshtastic traffic already, you may benefit from staying on channel 0 to maximize connectivity with existing nodes. However, if:

• You're running a private community network that doesn't want to receive or interfere with strangers
• You've identified interference at the default frequency with an SDR
• You want to operate on a less crowded frequency in a dense metropolitan area

...then changing to a different channel number makes sense.

Channel Number Coordination

Within your community network, all nodes must use the same channel number (along with the same modem preset and channel key). Keep a community coordination document:

# Check current channel number:
meshtastic --get lora.channel_num

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

# Calculate actual center frequency:
# US, LongFast: 906.875 + (3 * 0.125) = 907.250 MHz

Bandwidth and Channel Separation

For two independent networks to have true RF isolation, their channels need to be separated by at least 1x their bandwidth (125 kHz for LongFast). Practical guideline:

Modem Preset	Bandwidth	Min Separation for Isolation
LongFast	125 kHz	2 channel numbers (250 kHz)
MediumFast	250 kHz	2 channel numbers (500 kHz)
ShortFast	250 kHz	2 channel numbers (500 kHz)
ShortTurbo	500 kHz	2 channel numbers (1000 kHz)

If two networks operate on adjacent channels with the same bandwidth, they'll experience some co-channel interference but won't be completely isolated. For most community situations, 2 channel numbers separation is sufficient.