meshtastic/docs/developers/device/radio-settings.md

id	title	sidebar_label
radio-settings	Radio Settings	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 ERP (Effective Radiated Power, see this site for more information).

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 ERP.

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.

Data-rates

About

Various data-rates are selectable when configuring a channel and are inversely proportional to the theoretical range of the devices.

Considerations:

• Spreading Factor - How much we "spread" our data over time.
  • Each step up in Spreading Factor doubles the airtime to transmit.
  • Each step up in Spreading Factor adds about 2.5db extra link budget.
• Bandwidth - How big of a slice of the spectrum we use.
  • Each doubling of the bandwidth is almost 3db less link budget.
  • Bandwidths less than 31 may be unstable unless you have a high quality Crystal Oscillator.
• Coding Rate - How much redundancy we encode to resist noise.
  • Increasing coding rate increases reliability while decreasing data-rate.
  • 4/5 - 1.25x overhead
  • 4/6 - 1.5x overhead
  • 4/7 - 1.75x overhead
  • 4/8 - 2x overhead

Pre-Defined

We have six predefined channels. These are the most common settings and have been proven to work well:

Channel setting	Alt Channel Name	Data-rate	SF / Symbols	Coding Rate	Bandwidth	Link Budget
Short Range / Fast	Short Fast	18.89 kbps	7 / 128	4/5	500	134dB
Short Range / Slow	Short Slow	4.69 kbps	7 / 128	4/5	125	140dB
Medium Range / Fast	Medium Fast	1.2 kbps	10 / 1024	4/6	250	146dB
Medium Range / Slow	Medium Slow	0.75 kbps	11 / 2048	4/7	250	148dB
Long Range / Fast	Long Fast	0.19 kbps	9 / 512	4/8	31	153dB
Long Range / Slow	Long Slow	0.13 kbps (default)	12 / 4096	4/8	125	154dB

Note: The link budget used by these calculations assumes a transmit power of 17dBm and an antenna with 0dB gain. Adjust your link budget assumptions based on your actual devices. Data-rate in this table is actual measured but doesn't count mesh overhead, hops and retransmissions.

Custom Settings

You may want to select other channels for your usage. The other settings can be set by using the Python API.

meshtastic --setchan spread_factor 10 --setchan coding_rate 4 --setchan bandwidth 125

After applying the settings, you will need to restart the device. After your device is restarted, it will generate a new crypto key and you will need to share the newly generated QR Code or URL to all your other devices.

Some example settings:

Data-rate	SF / Symbols	Coding Rate	Bandwidth	Link Budget	Note
37.50 kbps	6 / 64	4/5	500	129dB	Fastest possible speed
3.125 kbps	8 / 256	4/5	125	143dB
1.953 kbps	8 / 256	4/8	125	143dB
1.343 kbps	11 / 2048	4/8	500	145dB
1.099 kbps	9 / 512	4/8	125	146dB
0.814 kbps	10 / 1024	4/6	125	149dB
0.610 kbps	10 / 1024	4/8	125	149dB
0.488 kbps	11 / 2048	4/6	125	152dB
0.336 kbps	11 / 2048	4/8	125	152dB
0.073 kbps	12 / 4096	4/5	31	160dB	Twice the range and/or coverage of "Long Slow", low resilience to noise
0.046 kbps	12 / 4096	4/8	31	160dB	Twice the range and/or coverage of "Long Slow", high resilience to noise

The link budget used by these calculations assumes a transmit power of 17dBm and an antenna with 0dB gain. Adjust your link budget assumptions based on your actual devices.

These channel settings may have not been tested. Use at your own discretion. Share on https://meshtastic.discourse.group with your successes or failure.

Cryptography

The preshared key used by the devices can be modified.

• 0 = No crypto
• 1 = Default channel key
• 2 - 10 = The default channel key, except with 1 through 9 added to the last byte

Use of cryptography can also be modified. To disable cryptography (maybe useful if you have Ham radio license):

meshtastic --setchan psk 0