-Cathode ray tube (CRT) assembly; it includes: . a high resolution color CRT (Shadow-mask type) with electrostatic focus and electromagnetic deflection, . deflection yokes, . magnetic shield.
-Very high voltage (VHV) power supply: It provides all the potentials necessary for the CRT (anode, focus and G2 electrodes).
-
One analog board; it includes:
. deflection amplifiers,
. convergence circuits,
. video amplifiers,
. brightness control,
. monitoring circuits.
-
One symbol generator (SG) block
-Interconnection board: It realizes the interconnection between the DU and the DMC and, inside the DU, between the SG board, the analog board and the power supply.
-Low voltage (LV) power supply: The low voltage power supply is supplied with 115V - 400 Hz from the aircraft electrical power.
4. Interface
_________
(Ref. ATA 31-62-00-WT)
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CRT - Block Diagram Figure 003
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5. Component Description
_____________________
A. DMC
(1) General
(a) System operation The configuration of the three DMCs and the six DUs in the EIS ensures redundancy, thanks to switching capabilities of individual DMCs to the DUs. The three DMCs are identical and therefore interchangeable. (Ref. Fig. 004) During normal operation:
-DMC1 drives CAPT PFD, CAPT ND and upper ECAM DU
-DMC2 drives F/O PFD, F/O ND and lower ECAM DU
-DMC3 is a back up (hot spare) unit.
In case of a breakdown of DMC1 or DMC2, the back up DMC3 is
switched on accordingly.
In case of a breakdown of a DU, the DMC channel which drives this
DU is switched to the alternate channel of another DU , which
undertakes the task of the failed DU.
(b) DMC operation The DMC can be divided into four basic sections:
-data acquisition
-PFD channel
-ND channel
-ECAM channel.
(Ref. Fig. 005)
The data acquisition section enables the DMC to handle all input
and output signals from/to the other avionic systems in the
aircraft.
The I/O interface 1 to 3 boards and the WXR (weather radar) board
in the unit are responsible for accomplishing this task. The
hardware contents of the three I/O interface boards are almost
identical ; they differ, however, in their software contents.
(Ref. Fig. 006)
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EIS Configuration Figure 004
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DMC - Data Flow Figure 005
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INTENTIONALLY BLANK
1 1
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DMC - Block Diagram
Figure 006
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1 The data acquisition section can handle 60 discrete inputs, 54 ARINC 429 inputs, 4 WXR channels, 3 RS 422 data link inputs and 6 RS 232C data link inputs as well as 12 discrete outputs and 3 ARINC 429 outputs. The discrete input signals, which define system-commands, are received by the I/O interface boards, and each signal is transformed into 2 x 16-bit words. These words are then routed to the COMMON RAM (located on the DPU 1 (PFD) board), where they are stored in their appropriate locations for use by the DPU boards. The ARINC 429 input (high or low speed) signals, which represent navigational information, are also received by the I/O interface boards. They are checked for validity and if valid, relabelled and stored in the COMMON RAM in their appropriate locations for use by the DPU boards. The RS 422 data link inputs, which represent texts/ messages, etc. generated by the FWC and to be displayed on the ECAM DU, are received serially by the I/O interface boards. They are converted into parallel bits and stored in the COMMON RAM for use by the DPU 3 (ECAM) board. The RS 232C data the COMMON RAM for use by the DPU 3 (ECAM) board. The RS 232C data link inputs (one each to the three I/O interface boards and the three DPU boards) are used for maintenance purposes only. The discrete output signals generated in the DMC and which represent validity signals for each channel (PFD, ND, ECAM), etc. as well as ARINC 429 output signals (2 low speed and 1 high speed) also generated in the DMC are fetched from the COMMON RAM under control of a DPU board and routed to external avionics systems via the I/O interface board. Four input channels as per ARINC 453 specifications feed WXR data from the weather radar transceiver to the WXR board; the WXR data format conforms with the ARINC 708 specification.The data is processed on this board, under the control of the DPU 2 (ND) to draw a color WXR map on the ND, which shows the weather conditions in front of the aircraft. The main function of each of the three independent channels -PFD, ND and ECAM - is to process the relevant input signals received by the data acquisition section and prepare data, which can be used by the DUs to draw the required symbols or pictures simultaneously. The processors on the boards DPU1 (PFD), DPU2 (ND) and DPU3 (ECAM) perform this function. All three boards are almost identical in hardware contents (except for the DPU1 (PFD), which contains the COMMON RAM, the BITE memory and the bus arbiter contains the COMMON RAM, the BITE memory and the bus arbiter additionally); they differ, however, in the software implemented on.
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