Page 204 Doc # 6.02.01 09 Jan 2003 Rev. 4
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AMM
Section 34-54
Distance Measuring Equipment (DME)
1. General
This Section tells you about the distance measuring equipment (DME) system that can be installed in the DA 40. Refer to the manufacturer's manuals for more data about the equipment. Refer to Chapter 92 for the wiring diagrams.
The DME system consists of the following items:
) DME receiver.
) Remote DME switch.
) DME antenna.
The audio panel controls the audio input from the DME (refer to Section 23-50).
2. Description and Operation
The DME gives the following information:
) Distance to DME ground stations.
) Ground speed.
) Time-to-station.
) Ground station identification by means of audio reception.
The DME measures the time required for signals to travel from the airplane to the ground station and
back to the airplane. The distance to the ground station is calculated from that time.
This distance, known as 'slant range distance', should not be confused with actual along-the-ground
distance. The difference between actual ground distance and slant range is least at low altitude and/or
long range. If the range is three times the altitude or greater, error is negligible.
The system determines the ground speed by measuring the rate of change in slant range distance with
time.
To obtain accurate ground speed, the airplane must be tracking directly to or from the station. To
obtain accurate time to station, the airplane must be tracking directly to the station.
Doc # 6.02.01 Page 1
Rev. 4 09 Jan 2003
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AMM
Distance to Station Station Frequency, RMT/FREQ/GS/T function
ON/OFF Switch Frequency Selector
Knobs
Figure 1: Bendix/King KN 62A DME Receiver
DME Channel
NAV 1/NAV 2
Switch
Figure 2: Remote DME Switch
34-54-00
Navigation
AMM
A. Bendix/King KN 62A DME Receiver
Figure 1 shows the Bendix/King KN 62A digitally-tuned, solid-state DME receiver. It is located in % the avionics rack in the instrument panel, see Chapter 31.
% The avionics bus supplies power to the DME receiver. The ALT/BAT switch (Lycoming version)
% or ELECTRIC MASTER key switch (TAE version) and the AVIONIC MASTER switch must be set to ON to supply power through the DME circuit-breaker to the DME receiver. Refer to Chapter 92 for the wiring diagrams.
The DME receiver has a gas-discharge display with automatic dimming which shows the following:
) Range, speed, and time-to station when the unit is in RMT or GS/T mode.
) Range and frequency when the unit is in FREQ mode.
) When the KN 62A is in search mode, dashes are displayed instead of range, speed and time-to-station.
The DME receiver has these controls:
) ON-OFF switch. It gives power to the unit.
) RMT-FREQ-GS/T switch. It determines both the information displayed and the channeling source for the KN 62A.
) In 'remote' (RMT) mode, the KN 62A is remote-channeled by the NAV receiver that is selected with the remote DME switch (see Paragraph B). The display shows range, speed, and time-to-station.
) In 'frequency' (FREQ) mode, the KN 62A is channeled from its own frequency selection knobs. The display shows range and frequency.
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