FPV: Equipment For FPV

Diversity in FPV

What is Diversity?

The term diversity is when two or more radio signals are received from the FPV vehicle. The opposing signals are then compared, resulting in the best overall signal being chosen. There are two known methods of diversity – the monitoring of a voltage pin and picture comparison.

Try to invest in a module with more than two inputs as you can then combine multiple antenna to get the best possible results.

Here’s a bit more of an in depth look into each method….

Voltage Pin Monitoring

Here the voltage pin is monitored on the RX module. The pin contains a voltage output that mirrors the signal strength coming from the module.  In order to select the correct signal, the diversity controller compares what is called the Receiver Signal Strength Indication (RSSI) voltage, selecting the strongest signal to give the best picture. The most able of the compared signals is then selected by the diversity controller.

Picture Comparison

The second arrangement categorically compares pictures and also analyses noise in each received video signal. By doing this it selects what signal it believes to be the best to pass on.

What Will The Picture Quality Be Like?

This is going to come down to your receiver antenna choice. The choice is down to the FPV pilot, just bear in mind that you can mix up any antenna selection you want. The reason for doing this is to get the very best that you can out of your system. For instance, one antenna may be proficient in one way but may become deficit in another. This way you can adopt various antenna at the same time.

Examples Of Use:

I’m going to use a double antenna input as an example.

If you were to set up a clover leaf/skew-planar circular polarized omni antenna, the alternative choice could be a circular polarized patch antenna. In flight, the clover leaf/skew-planar would retain the better reception as a result of its 360 degree response pattern, leading the diversity module on to select the superior of the two.

Alternatively you could purchase a patch antenna which is linear polarized. These contain 2 antennas inside with one being mounted vertically and the other being mounted horizontally. You’ll be able to see two wires coming out, each one being for each antenna.  Simply plug one wire into each input so when the plane is in flight, flying level, away and towards yourself the vertical antenna will receive the better signal. This will also be apparent when performing manoeuvres or if you have your FPV banked. Again the diversity module will then select the best of the two.

Thanks for reading!