Add link budget to radio-settings.md

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Jm 2021-02-06 10:02:23 -08:00
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@ -55,12 +55,14 @@ Considerations:
We have four 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 |
|:---------------------------|:-----------------|:---------------------|:-------------|:------------|:----------|
| Short range (but fast) | Short Fast | 21.875 kbps | 7 / 128 | 4/5 | 125 |
| Medium range (but fast) | Medium | 5.469 kbps | 7 / 512 | 4/5 | 500 |
| Long range (but slower) | Long Alt | 0.275 kbps | 9 / 512 | 4/8 | 31 |
| Very long range (but slow) | Long Slow | 0.183 kbps (default) | 12 / 4096 | 4/8 | 125 |
| Channel setting | Alt Channel Name | Data-rate | SF / Symbols | Coding Rate | Bandwidth | Link Budget |
|:---------------------------|:-----------------|:---------------------|:-------------|:------------|:----------|:------------|
| Short range (but fast) | Short Fast | 21.875 kbps | 7 / 128 | 4/5 | 125 | 134dB |
| Medium range (but fast) | Medium | 5.469 kbps | 7 / 128 | 4/5 | 500 | 140dB |
| Long range (but slower) | Long Alt | 0.275 kbps | 9 / 512 | 4/8 | 31 | 153dB |
| Very long range (but slow) | Long Slow | 0.183 kbps (default) | 12 / 4096 | 4/8 | 125 | 154dB |
The link budget used by these calculations assumes a transmit power of 17dBm. Adjust your link budget assumptions based on your actual devices.
### Custom Settings
@ -68,19 +70,24 @@ You may want to select other channels for your usage. The other settings can be
> meshtastic --setchan spread_factor 10 --setchan coding_rate 8 --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 | Note |
|:---------------------|:-------------|:------------|:----------|:-----|
| 3.125 kbps | 8 / 256 | 4/5 | 125 | |
| 1.953 kbps | 8 / 256 | 4/8 | 125 | |
| 1.343 kbps | 11 / 2048 | 4/8 | 512 | |
| 1.099 kbps | 9 / 512 | 4/8 | 125 | |
| 0.814 kbps | 10 / 1024 | 4/6 | 125 | |
| 0.610 kbps | 10 / 1024 | 4/8 | 125 | |
| 0.488 kbps | 11 / 2048 | 4/6 | 125 | |
| 0.336 kbps | 11 / 2048 | 4/8 | 125 | |
| 0.092 kbps | 12 / 4096 | 4/8 | 62 | |
| 0.046 kbps | 12 / 4096 | 4/8 | 31 | Twice the range of "Long Slow" |
| 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 of "Long Slow", low resliance to noise |
| 0.046 kbps | 12 / 4096 | 4/8 | 31 | 160dB | Twice the range of "Long Slow", high resliance to noise |
The link budget used by these calculations assumes a transmit power of 17dBm. Adjust your link budget assumptions based on your actual devices.
These channel settings may have not been tested. Use at your own discression. Share on https://meshtastic.discourse.group with your successes or failure.