RSSI_RANGE support for old APMrover firmware

I have installed Ardurover to a apm mini PRO .
Last version available seems to be 2.51beta .

I have read in wiki , that RSSI_RANGE was added to ArduRover, but i can not see it available in the last version for APM

Can you port this piece of code from pixhawk firmware?
Arduplane for APM supports this param too .

I will love to have correct rssi percent while iā€™m in the middle of the sea :slight_smile: