Reading RSSI from a FrySKY X8R Transmitter with an Arduino

What is RSSI??

RSSI (Received Signal Strength Indication) is a measure of the signal strength between the Radio Control transmitter (Figure 1) and the receiver on your drone. The unit for RSSI is decibels (dB), these are used to quantify the power of an electrical signal. The signal strength of your radio control signal becomes very important when you are about to go out of receiver range!