Received Signal Strength Indication (RSSI)

This article shows how to get the Received Signal Strength Indication (RSSI) from an FrSky receiver to APM.

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Provide RSSI from FrSky receiver to APM.

  • Select the input pin with the RSSI_PIN parameter.
  • However some of receivers such as FrSky D8R-XP output 0 - 3.3 V.
  • For that reason I’ve added new parameter: RSSI_RANGE.
  • This was also a requested issue previously: https://github.com/ArduPilot/ardupilot/issues/648
  • When the RSSI_RANGE parameter is set to your radio’s maximum RSSI voltage the RSSI rxrssi is shown in the range 0-100.
  • The ability to set the RSSI_RANGE parameter has been added to Mission Planner in the Full Parameter List:
../_images/mp_rssi_parameter.png

Complete System with RSSI addition

../_images/complete_amp2_system_with_rssi.jpg

RSSI Filter

A 4.7k resistor and 10uF capacitor are used to filter out the pulses from the receiver’s RSSI output.

../_images/rssi_circuit_to_filter_out_pulses.jpg

RSSI Connections

../_images/rssi_connections_3.jpg

RSSI embedded in PWM from UHF systems (Pixhawk)

Both EZ-UHF and OpenLRS have the option of embedding RSSI into a PWM channel, saving you from having to add filters, etc. You can use any channel from channel 5 and up, but keeping the on channel 9 or above will keep your regular servo channels free.

Set up your UHF system to embed the RSSI into the desired channel and then change the following parameters:

  • RSSI_ANA_PIN : 103
  • RSSI_TYPE : 2
  • RSSI_CHANNEL : Your selected channel from above.

Developed and illustrated by Lukasz - Thank You - Hope this helps.