radar altimeter AN/APN 209

DESCRIPTION

The radar altimeter is a short pulse, terrain tracking and altitude sensing radar system that measures and visually indicates by pointer and digital display actual clearance in feet between the helicopter and terrain over a range from 0 to 1500 feet. The indicator contains all the electronic components necessary for the generation, reception, and tracking of the radar pulses. The indicator provides precise altitude indications with a manually set low-level and high-level warning flag to warn when a predetermined low or high altitude limit has been reached. Simultaneous operation of the AN/APR-39, radar warning receiver and the AN/APN-209 radar altimeter will cause a strobe to appear on the AN/APR-39 CRT and an audio tone can be heard in the headset for IGE hover.

CONTROL / INDICATOR	FUNCTION
1. LO SET control knob	Turns facility on and off, and sets low limit index.
2. LO level warning flag	Indicates LO when altitude pointer indicates below low limit index.
3. Low limit index	Indicates low altitude limit index setting. Actuates LO level warning flag when limit is reached.
4. Hi level warning flag	Indicates HI when altitude pointer indicates above high limit index.
5. High limit index	Indicates high altitude limit index. Actuates HI level warning flag when limit is reached.
6. Altitude pointer	Indicates actual altitude in feet from helicopter to terrain ( zero to 1500 feet ).
7. HI SET control knob	Sets high altitude limit index and actuates self-test mode.