Frsky D8R-II receiver flashed with XP firmware is switched to PPM mode, by shorting ch 3-4 signal pins with a jumper (blue).
This way ch1 turns into PPM output and ch2 into RSSI output. RSSI is yellow wire in the video, while ground is green wire.
After initial on-off demo, I am switching Tx in range check mode, to reduce power, and walked to other room, RSSI voltage and beeps signaling this situation.
Beware, the RSSI output is not a continuous voltage, but pulsed PWM signal, to use it for an OSD a filter is required, about 10-22k series resistor with 1-5uF capacitor to ground are ok values. No filter was used in this demo because voltmeter integrates the pulses when doing measurement.
