atbetaflight/docs/Rssi.md

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# RSSI
RSSI is a measurement of signal strength. RSSI is very handy so you know when you are going out of range or there is interference.
Some receivers have RSSI outputs. 3 types are supported.
1. RSSI via PPM channel
2. RSSI via Parallel PWM channel
3. RSSI via PWM with PPM RC that does not have RSSI output - aka RSSI PWM
## RSSI via PPM
Configure your receiver to output RSSI on a spare channel, then select the channel used via the cli.
e.g. if you used channel 1 then you would set:
```
set rssi_channel = 1
```
## RSSI via Parallel PWM channel
Connect the RSSI signal to any PWM input channel then set the RSSI channel as you would for RSSI via PPM
## RSSI PWM
Connect the RSSI PWM signal to the RC2/CH2 input.
Enable using the RSSI_PWM feature:
```
feature RSSI_PWM
```
The feature can not be used when RX_PARALLEL_PWM is enabled.
### RSSI PWM Providers
When using RSSI PWM it is possible to use standard ~18ms RSSI signals or a faster 1khz/1m RSSI signal.
The RSSI output on the FrSky X8R (and probably the FrSky X6R) is 1khz.
To support the 1khz rate enable it via the cli:
```
set rssi_pwm_provider = 1
```
| Value | Meaning |
| ----- | ----------- |
| 0 | ~18ms pulse |
| 1 | 1ms pulse |