(2)
Set the transponder select switch on the ATC control panel to the 1 position.
(3)
Push and release the self-test switch on the left ATC transponder.
(a) Make sure the self-test passes and no faults are detected.
(4)
Set the transponder select switch on the ATC control panel to the 2 position.
(5)
Push and release the self-test switch on the right ATC transponder.
(a) Make sure the self-test passes and no faults are detected.
(6)
Remove electrical power if it is not necessary (Ref 24-22-0/201).
5C8
May 01/99 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 34-53-31 Page 403
DME SYSTEM DESCRIPTION AND OPERATION
EFFECTIVITY
GJ ALL EXCEPT B-2509 and B-2510
1. General
A. The DME (Distance Measuring Equipment) system continuously measures the slant range distance between the airplane and a selected ground station and displays it on appropriate DME indicators as nautical miles. The DME interrogator and VHF navigation receiver are tuned simultaneously by the VHF NAV control panel.
B. The interrogator unit transmits a pulse-coded interrogation signal that actuates a corresponding ground station reply. This reply signal is received and processed by the interrogator. The time interval between the interrogation signal transmitted from the airplane and the ground station reply signal received by the airplane is measured, converted into distance (nautical miles), and displayed on appropriate DME indicators.
C. Two DME systems are installed in the airplane. Each system consists of an interrogator (receiver-transmitter) unit, an antenna, a VHF NAV control panel, and a miles readout on the appropriate sector of the dual DME indicators.
D. The DME system operates on 115-volt, 400-Hz power supplied through circuit breakers DME 1 - AC on load control center P18 and DME-2 AC on load control center P6.
E. The output of the interrogator is applied to the appropriate digital readout of both DME indicators. A sample pulse is taken from the interrogator and coupled to the ATC system, which operates in the same general frequency range. This pulse acts as a suppression pulse. An audio signal from the DME interrogator is applied to the flight interphone system. The DME interrogator provides distance information to the performance data computer system by an analog pulse pair and DME valid signal output (Ref 34-18-0).
5C8
Jun 20/85 34-55-0 Page 1
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
K73543
DME System Component Location 5C8
34-55-0 Figure 1 Jun 20/88
Page 2
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
2. Control Panel
A. Since the DME system operates in conjunction with the VOR/ILS navigation system, controls for both are located on the same control panel and consist of the VHF NAV frequency selectors, a volume control, test switches, and a DME function selector. DME system No. 1 is controlled from the captain's control panel and DME system No. 2 from the first officer's control panel.
B. The DME function selector control is a 3-Position switch with positions: STBY, NORM or ON and 0 RIDE.
C. The DME TEST pushbutton initiates a system self-test when pressed.
D. On GJ ALL EXCEPT B-2504 and B-2505, a transfer switch MR) allows two VOR frequencies to be selected at one time and switching between the two can be done at any time.
3. Antennas
A. The DME antennas are conventional flush-mounted or blade-type units which are connected to the interrogator units by coaxial cable. The No. 1 system antenna is installed on the bottom of the fuselage at station 468. The No. 2 system antenna is installed at station 580. Each antenna performs both transmitting and receiving functions for its respective DME system in the frequency range of 960 to 1215 MHz.
4. Interrogator Units
A. Each interrogator unit provides the capability to compute the time interval between transmitted and received pulse-pair signals, convert this time difference to distance, and apply this information to the DME indicator.
B. The interrogator units are standard 112 ATR short assemblies which mount (side-by-side) on a shelf in the electrical/electronics equipment center (Fig. 1).
C. Each DME interrogator provides an analog pulse pair and DME valid signal to the performance data computer (34-18-0).
D. The interrogators operate in the frequency range of 962 to 1213 MHz. There are 126 transmitting channels between 1025 and 1150 MHz and two 63 channel receiving bands from 962 to 1024 and 1151 to 1213 MHz.
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