DME SYSTEM - GENERAL DESCRIPTION

General

The DME system has two DME interrogators and two antennas.

Description

The interrogators get manual tune inputs and flight management computer system (FMCS) autotune inputs from the navigation control panel. If the NAV control panel tune inputs fail, the interrogators get autotune inputs directly from the FMC.

The DME system sends data to the display electronics units to show on the primary flight displays (PFDs) and navigation displays (NDs).

The DME system sends data to these units:

· Flight control computers (FCC)

· Flight management computer System (FMCS)

· Flight data acquisition unit (FDAU)

· Remote Electronics Unit (REU).

The FCCs use DME data as an input to calculate the VOR capture point in the autopilot VOR mode. The DME data is also used in the VOR mode to find when over station is sensed (OSS) for the VOR ground station.

The FMCS uses DME data to calculate FMC position updates. The flight data acquisition unit receives DME data, formats it, and sends it to the flight data recorder.

The REU receives audio from the DME station and sends it to the flight deck headsets and speakers.

The DME system sends and receives a suppression pulse between these units:

· DME

· ATCs

· TCAS.

The DME interrogator receives the station audio identifiers and sends them to the remote electronics unit (REU).