The AN/ARN-149(V) from Collins Aerospace is an Automatic Direction Finder that operates from 100 to 2199.5 kHz with 500 Hz channel spacing. This lightweight, low-frequency automatic direction-finding solution is easy to install and consists of a receiver, control system, and antenna.
The system has a solid-state receiver which eliminates all moving parts such as goniometers, synchros, and mechanical tuners. Quadrantal Error Correction (QEC) is set by aircraft connector strapping, eliminating corrector modules and airframe-specific internal adjustments. The antenna combines the loop and sense antennas and preamplifiers in one compact housing, thereby eliminating expensive sense panels, couplers, and special prefabricated cable assemblies. It is DO-160 rated for hard mounting in helicopters and fixed-wing aircraft.
The AN/ARN-149(V) LF ADF system provides automatic pointing to low and medium-frequency non-directional beacons (NDB), standard broadcast stations, and emergency stations. The frequency is selected in 500 Hz increments on the control, or via the MIL-STD- 1553B data bus. The receiver processes the signals received from the integrated dual loop and sense antenna and provides bearing information to a standard radio magnetic indicator (RMI) via the 3-wire synchro interface and to either a cockpit display unit (CDU) or an aircraft navigation system computer via the MIL-STD-1553B bus interface.
An aural output provides station identification, weather reporting, and AM broadcast audio. The control provides a wide selection of features for the receiver including ON/OFF, antenna mode, ADF mode, emergency presets, frequency selection, the tone for keyed CW stations, volume control, and test initiation. All of these features except for the ON/OFF and pre-set emergency frequency selections are controllable via the MIL-STD-1553B bus.