*
Air/ground relays

*
AFDCs.

The CDUs send a frequency source select discrete to cause the receiver to select the tune input from either the CDU or the AIMS cabinets. The resistor assemblies pull up the discretes to 28v dc. The left CDU sends a ground discrete to the left and center receivers when the discrete is true. The right CDU sends a ground discrete to the right receiver when the discrete is true.
The air/ground relays send a discrete to the receivers to inhibit tests in the air. The discrete also supplies flight legs data as a backup to the AIMS cabinets flight legs data.
The AFDCs send a discrete to inhibit ILS tune inputs in approach (APP) mode when the airplane is at or below 1500 feet, and there is a localizer or glideslope signal capture. This prevents the flight crew from tuning the receivers.
Analog Outputs
Each receiver sends an audio output to the AMU. The pilots use the audio control panels (ACP) to send ILS audio to the headsets and flight interphone speakers.
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ILS -ANALOG AND DISCRETE INTERFACE

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ILS -ARINC 429 INTERFACE

General
These are the LRUs that have interface with the multi-mode receivers (MMRs) on ARINC 429 data buses:
*
Left and right control display units (CDUs)

*
Left and right AIMS cabinets

*
Left, center, and right autopilot flight director computers (AFDCs)

*
Ground proximity warning computer (GPWC).

CDU
The left and right CDUs supply alternate tune inputs directly to the receivers if the AIMS tune inputs fail. The left CDU sends alternate tune signals to the left and center receivers. The right CDU sends alternate tune signals to the right receiver.
AIMS
The right AIMS cabinet sends manual or automatic tune inputs to the receivers on the left, center, and right tune buses.
The left AIMS cabinet sends test commands and flight legs data to the receivers on the left, center, and right CMC buses.
Receiver Outputs
Each receiver has two output buses. Output bus one supplies data to the onside AFDC. Output bus two supplies data to both AIMS cabinets.
Each receiver sends data to both AIMS cabinet to show ILS data on the PFDs and NDs. The receivers also send test status and fault reports.
The left receiver sends ILS data to the GPWC for mode five alerts.
Each receiver sends ILS data to the onside AFDC for autoland functions.
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ILS -ARINC 429 INTERFACE

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ILS -LOCALIZER ANTENNA INPUTS

General
The multi-mode receivers (MMRs) get localizer signal inputs from the localizer antennas in the nose radome or from the VOR antenna on the vertical stabilizer.
Antenna Inputs
Signal inputs from the VOR antenna on the vertical stabilizer go through the RF power dividers to the localizer antenna switches.
The antenna inputs go through the localizer antenna switches then to the receivers. The switches change the input from the VOR antenna on the vertical stabilizer to the LOC track antenna in the nose radome.
Antenna Switch Control
Each autopilot flight director computer (AFDC) controls its onside localizer antenna switch. Each switch sends antenna switch position feedback to its onside AFDC.
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777 AIRCRAFT MAINTENANCE MANUAL

ILS -LOCALIZER ANTENNA INPUTS

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ILS -GLIDESLOPE ANTENNA INPUTS

General
The multi-mode receivers (MMRs) get inputs from the glideslope capture antennas in the nose radome, or from the glideslope track antennas on the aft nose gear doors. The antenna inputs go through the glideslope antenna switch, then to the MMRs.
Antenna Inputs
Signal inputs from the glideslope track antenna on the left nose gear door go to the left and center receivers. Signal inputs from the glideslope track antenna on the right aft nose gear door go to the right receiver.
The left capture antenna signals go to the left receiver. The right capture antenna signals go to the center and right receivers.
　
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