The VOR/LOC/GS/MB  Radio Receiving Set AN/ARN-123(V)1 receives the combined VOR (VHF omni-range) and LOC ( localizer) signals over a frequency range of 108.00 to 117.95 MHz, GS ( Glideslope ) signals over a frequency range of 329.15 to 335.00 MHz, and MB ( Marker Beacon ) signals on 75.00 MHz from ground transmitters. The signals drive the pilot HSI and ADF as applicable, the gunner RMI radio bearing pointers, and the marker beacon lights as required. Audio signals may also be received , from the ground transmitters, through the helicopter's intercommunication system by placing the interphone control AUX switch in ON. The set enables the operator to determine his present position, direction to a given point, and fly a predetermined flight-path to a desired destination relative to a VOR facility. The localizer circuitry provides a visual display of the helicopter position relative to a localizer course. The marker beacon circuitry provides a visual display and aural tone to indicate helicopter position relative to a marker beacon transmitter.