Input Program Pins

The system select program pin input sets the system modulation rate and system identification. The modulation rate for the RA 1 system is 145Hz, the RA 2 system is 155Hz.

The aircraft installation delay (AID) program pin is grounded to the 57 feet selection. This calibrates the system so that the radio altitude is 0 feet at touchdown. It makes an allowance for these conditions:

· Length of the antenna cables

· Fuselage to ground distance

· Flare angle.

 

When grounded, the continuous data program pin selects noninterrupted RA data output at all times.