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117 lines
7.1 KiB
Plaintext
117 lines
7.1 KiB
Plaintext
---
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id: radio-settings
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title: Radio Settings
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slug: /overview/radio-settings
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sidebar_label: Radio Settings
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sidebar_position: 1
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---
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import {FrequencyCalculator} from "/src/components/tools/FrequencyCalculator";
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:::info
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Meshtastic is **not** LoRaWAN, Helium or TTN (TheThingsNetwork). Meshtastic uses the full spectrum frequency range designated to LoRa technology per region. This allows for several hundred possible frequency channels in the US region alone.
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:::
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:::info
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Power limits will generally be lifted in the software if `is_licensed` is set to `true`. See [HAM Mode](/docs/faq#amateur-radio-ham) for more information.
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:::
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## Channel Frequency Calculator
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<FrequencyCalculator />
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## Europe Frequency Bands
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### 433 MHz
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The maximum power allowed for Europe is +10 dBm ERP ([Effective Radiated Power](https://en.wikipedia.org/wiki/Effective_radiated_power)).
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The band range is from 433 to 434 MHz.
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There are four channels defined with the standard radio preset `LongFast`. After factory reset the radio will be set to channel 4 with a center frequency of 433.875 MHz.
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### 868 MHz
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The maximum power allowed for Europe is +27 dBm ERP ([Effective Radiated Power](https://en.wikipedia.org/wiki/Effective_radiated_power)).
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The band range is from 869.40 to 869.65 MHz. This is less than the 863–870 MHz range defined as SRD Band, but allows for a higher ERP and a duty cycle of 10%.
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There is one channel defined with the standard radio preset `LongFast`. After factory reset the radio will be set to channel 1 with a center frequency of 869.525 MHz.
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## North America Frequency Bands
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### 915 MHz (ISM Band)
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The maximum output power for North America is +30 dBm ERP ([Effective Radiated Power](https://en.wikipedia.org/wiki/Effective_radiated_power)).
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The band range is from 902 to 928 MHz.
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There are 104 channels defined with the standard radio preset `LongFast`. After factory reset the radio will be set to channel 20 with a center frequency of 906.875 MHz.
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## Data Rates
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### Considerations
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Various data-rate options are available when configuring a channel and are inversely proportional to the theoretical range of the devices.
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- **Spreading Factor (SF)** - How much we "spread" our data over time.
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- Each step up in Spreading Factor doubles the airtime to transmit.
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- Each step up in Spreading Factor adds about 2.5db extra link budget.
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- **Bandwidth** - How big of a slice of the spectrum we use.
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- Each doubling of the bandwidth is almost 3db less link budget.
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- Bandwidths less than 31 may be unstable unless you have a high quality Crystal Oscillator.
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- **Coding Rate** - How much redundancy we encode to resist noise.
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- Increasing coding rate increases reliability while decreasing data-rate.
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- 4/5 - 1.25x overhead
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- 4/6 - 1.5x overhead
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- 4/7 - 1.75x overhead
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- 4/8 - 2x overhead
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### Presets
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We have eight LoRa radio presets. These are the most common settings and have been proven to work well:
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| Channel setting | Alt Channel Name | Data-Rate | SF / Symbols | Coding Rate | Bandwidth | Link Budget |
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| :--------------------: | :--------------: | :-----------------: | :----------: | :---------: | :-------: | :---------: |
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| Short Range / Fast| Short Fast| 10.94 kbps| 7 / 128| 4/5| 250| 143dB|
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| Short Range / Slow| Short Slow| 6.25 kbps| 8 / 256| 4/5| 250| 145.5dB|
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| Medium Range / Fast| Medium Fast| 3.52 kbps| 9 / 512| 4/5| 250| 148dB|
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| Medium Range / Slow| Medium Slow| 1.95 kbps| 10 / 1024| 4/5| 250| 150.5dB|
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| Long Range / Fast| Long Fast| 1.07 kbps| 11 / 2048| 4/5| 250| 153dB|
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| Long Range / Moderate| Long Moderate| 0.34 kbps| 11 / 2048| 4/8| 125| 156dB|
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| Long Range / Slow| Long Slow| 0.18 kbps| 12 / 4096| 4/8| 125| 158.5dB|
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| Very Long Range / Slow| Very Long Slow| 0.09 kbps| 12 / 4096| 4/8| 62.5| 161.5dB|
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:::note
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The link budget used by these calculations assumes a transmit power of 22dBm and an antenna with 0dB gain. Adjust your link budget assumptions based on your actual devices. Data-rate in this table is the theoretical max but doesn't account for packet headers, hops and re-transmissions. Calculations based on data from the official [Semtech LoRa calculator](https://www.semtech.com/design-support/lora-calculator).
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:::
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### Custom Settings
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Custom settings can be applied by using [supported software](/docs/software).
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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.
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Some example settings:
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| Data-rate | SF / Symbols | Coding Rate | Bandwidth | Link Budget | Note |
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| :--------: | :----------: | :---------: | :-------: | :---------: | :----------------------------------------------------------------------- |
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| 37.50 kbps | 6 / 64 | 4/5 | 500 | 129dB | Fastest possible speed |
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| 3.125 kbps | 8 / 256 | 4/5 | 125 | 143dB | |
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| 1.953 kbps | 8 / 256 | 4/8 | 125 | 143dB | |
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| 1.343 kbps | 11 / 2048 | 4/8 | 500 | 145dB | |
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| 1.099 kbps | 9 / 512 | 4/8 | 125 | 146dB | |
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| 0.814 kbps | 10 / 1024 | 4/6 | 125 | 149dB | |
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| 0.610 kbps | 10 / 1024 | 4/8 | 125 | 149dB | |
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| 0.488 kbps | 11 / 2048 | 4/6 | 125 | 152dB | |
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| 0.073 kbps | 12 / 4096 | 4/5 | 31 | 160dB | Twice the range and/or coverage of "Long Slow", low resilience to noise |
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| 0.046 kbps | 12 / 4096 | 4/8 | 31 | 160dB | Twice the range and/or coverage of "Long Slow", high resilience to noise |
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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.
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These channel settings may not have been tested. Use at your own discretion. Share on https://meshtastic.discourse.group with your successes or failure.
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## Cryptography
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The pre-shared key (PSK) used by the devices can be an AES128 or AES256 sequence. Alternatively, encryption can be turned off, which may be useful if you are operating under a Ham Radio license.
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