NRF24L01 Pseudo Received Power Indication

If you need to know what the comparative signal strength of a transmitter is at a receiving node then you can do it like this

TX: Transmit 3 packets (or 4 if you are using PA+LNA module) each with a different setting for setPaLevel
RX: Listen for the packets and determine which packet was sent with the lowest power setting (you may not hear all of them)

you could use the power settings in an array

const uint8_t POWER[4] = {RF24_PA_MIN, RF24_PA_LOW, RF24_PA_HIGH, RF24_PA_MAX};

the power settings could be sent in a loop one after the other

    for (x=0; x<3; x++) {
      radio.setPALevel(POWER[x]);    // POWER[0] = MIN, POWER[1] = LOW, POWER[2] = HIGH
      payload[1] = x; // send power setting
      radio.stopListening();
      radio.write( payload, sizeof(payload) ); // dump payload to radio
      radio.startListening();
     delay(10);
    }

I ended up with this idea after requiring it for something else, it works just great !!

I found this particularily useful for finding when I am going out of range