-TEST OK (green) indicates that no fault is detected during the initiated (by pushbutton switch or by MCDU) self-test or during the power-up test.
-MMR FAULT (red) indicates that an internal fault is detected by the MMR itself.
-BUS IN FAIL (red) indicates that no control input is available.
-TEST ANT (red) indicates that a failed antenna (or coaxial cable)
is detected. The back of the MMR is equipped with one ARINC 600 size one connector, which includes three plugs:
-Top Plug (TP): connection with the GPS antenna
-Middle Plug (MP): service interconnection
-Bottom Plug (BP): connection with the power supply circuit, and the LOC and G/S coaxial interconnections.
(2)
Internal description
(Ref. Fig. 005A)
The MMR includes:
-an ILS RF module (RF)
-
a main ILS board (CMD)
-
a monitor ILS board (MON)
-
a GPS board (GPS)
-
a power supply module (POWER SUPPLY)
-
a High Intensity Radiated Field interconnect module (HIRF).
1EFF : ALL 1 34-36-00Page 19 1 1 Config-2 Aug 01/05 1 1 1CES 1
MMR - Block Diagram
Figure 005A
R 1EFF : 001-049, 101-149, 151-199, 201-299, 1 34-36-00Page 20 1301-399, 401-499, 1Config-2 Aug 01/05 1 1 1CES 1 The primary function of the MMR is to receive and process ILS and GPS signals. The ILS signals, including both localizer and glide slope, are used to determine flight path deviations during precision approach and landing, and are supplied to the aircraft flight control and instrument systems. These deviations are based on radio frequency signals that the unit receives from a ground-based instrument landing system. The GPS receiver simultaneously tracks signals from up to fifteen GPS satellites. The signals are processed to generate a three-dimensional position and a precise time. The receiver generates an estimate of the positional accuracy provided. An integrity alert is activated if an unannounced satellite malfunction is detected. The receiver has the capability of excluding satellites that are malfunctioning. It is able to incorporate external altimeter data to improve the availability of its integrity monitoring functions.
(a)
ILS RF module (RF) This module converts (filters, amplifies and demodulates) the RF signals received by the localizer and glide slope antennas into analog signals for processing by the Digital Signal Processor (DSP). The module consists of two RF sections, one for the VHF localizer signals and one for the UHF glide slope signals.
(b)
Main ILS board (CMD) The main ILS board controls the ILS mode of operation, generates the audio and deviation outputs, controls the aircraft interfaces and performs the maintenance tasks (for CFDIU interface). The board is divided into five sections:
-A/D converter (ADC) which digitizes the localizer and glide slope signals from the ILS RF module.
-DSP section which formats and sends to the Precision Approach Navigator (PAN) the deviations computed with the depth of modulation of the 90Hz and 150Hz.
-PAN section which processes the data from the DSP section to provide the localizer and glide slope deviation information to the Input/Output section (I/O). The PAN compares information from the monitor ILS board with the information it has calculated itself. The PAN sends to the maintenance section the in-line test (BIT) results from all the boards installed in the MMR (RF, CMD, MON, GPS and POWER SUPPLY).
-maintenance section which provides the interface with the Centralized Fault Display Interface Unit (CFDIU).
-I/O section which consists of ARINC 429 drivers and receivers and discrete I/O logic. The I/O section provides the interface with aircraft systems.
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(c)
Monitor ILS board (MON) The monitor ILS board provides a redundant dissimilar signal processing path for the localizer and glide slope signals from the ILS RF module. It also includes an ADC, a DSP, a PAN and an I/O section (as CMD). In order to determine if the main ILS board (CMD) operates properly, the MON PAN calculates the deviation outputs and compares the results against those being transmitted over the ARINC 429 ILS output ports. If the calculations from the two PANs are excessively different, the MON PAN asks the CMD PAN to set the deviation words to indicate failure. The MON PAN shuts down the output buses if the SSM of the output words does not indicate failure when required.
(d)
GPS Board (GPS) The GPS board receives RF signals through an active GPS antenna, filters, mixes, and performs analog-to-digital conversion and outputs position, velocity, time and integrity data. It also outputs a time mark discrete signal to synchronize users with the raw data sent by this board. The GPS board is divided into four sections:
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