*
ADF -automatic direction finder

*
AIMS -airplane information management system

*
air/gnd -air ground

*
altn -alternate

*
AM -amplitude modulation

*
AMU -audio management unit

*
ant -antenna

*
ARINC -Aeronautical Radio, Inc.

*
BFO -beat frequency oscillator

*
CDU -control display unit

*
CMCF -central maintenance computing function

*
kHz -kilohertz

*
MAT -maintenance access terminal

*
NCD -no computed data

*
ND -navigation display

*
QEC -quadrantal error correction

*
RF -radio frequency

*
SDI -source destination indicator

*
sta -station

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AUTOMATIC DIRECTION FINDER SYSTEM -INTRODUCTION

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ADF SYSTEM -GENERAL DESCRIPTION

General
The ADF system has two receivers and two antennas.
Description
The ADF antenna assembly has both the loop and sense antennas. The antenna receives signals from the ground stations and sends them to the ADF receiver.
The ADF receiver calculates the bearing to the station and sends it to the AIMS cabinets to show on the navigation displays (ND).
You can tune the ADF receivers manually from the left or right CDU. The airplane information management system does not autotune the ADF receivers. The receivers can get tune inputs directly from the left or right CDU (alternate tune) if the tune inputs through the AIMS cabinets fail.
The ADF receiver processes the station audio and sends it to the audio management unit (AMU).
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777 AIRCRAFT MAINTENANCE MANUAL

ADF SYSTEM -GENERAL DESCRIPTION

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D633W101-BEJ  Jan 05/2002 

ADF SYSTEM -FLIGHT DECK COMPONENT LOCATION

General
These are the components on the flight deck that interface with the ADF system:
*
Left and right EFIS control panel (CP)

*
Captain and first officer navigation display (ND)

*
Left and right control display units (CDUs)

*
Audio control panels (ACPs).

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ADF SYSTEM -FLIGHT DECK COMPONENT LOCATION

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ADF SYSTEM -MAIN EQUIPMENT CENTER AND FUSELAGE COMPONENT LOCATION
General
The ADF antennas are on the top of the fuselage. The left and right ADF receivers are in the main equipment center on the E1 and E2 racks.
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ADF SYSTEM -MAIN EQUIPMENT CENTER AND FUSELAGE COMPONENT LOCATION

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D633W101-BEJ  Jan 05/2002 

ADF SYSTEM -POWER, ANALOG, AND DISCRETE INTERFACES

Power
The left and right ADF receivers get 115v ac from the left and right 115v ac transfer buses.
The ADF receivers send 12v dc to their ADF antennas.
ADF Antennas
The ADF antennas send AM ground station signals to the ADF receivers.
CDUs
The CDUs supply frequency source select discretes to the ADF receivers when the tune inputs from the AIMS fails. The resistor assemblies pull up the discretes to 28v dc. The left CDU sends a ground discrete to the left receiver when the discrete is true. The right CDU sends a ground discrete to the right receiver when the discrete is true.
Air/Ground Relay
The air/ground relay supply discrete inputs to the ADF receivers to:
*
Set flight legs (as alternate source, primary is from the CMCF of AIMS)

*
Inhibit test commands in the air.

AMU
The audio management unit (AMU) receives Morse code station identifier signals and audio from the receivers and sends them to the flight interphone speakers and headsets.
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ADF SYSTEM -POWER, ANALOG, AND DISCRETE INTERFACES

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