ADF - DESCRIPTION AND OPERATION

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1. General
The Automatic Direction Finder (ADF) is a radio navigation aid which provides :

an indication of the relative bearing of the aircraft to a selected ground station : this station operates in a frequency range of 190 to 1750 KHz
aural identification of the ground station.

The frequency range includes :

the standard commercial broadcast AM stations (550 to 1610 KHz) located at known co-ordinates around the world
the Non-Directional Beacons (NDB) (190 to 550 KHz).

The Automatic Direction Finder (ADF) is a radio navigation aid which provides :

an indication of the relative bearing of the aircraft to a selected ground station (150 to 1799 KHz)
aural identification of the ground station.

The frequency range includes :

the standard commercial broadcast AM stations (550 to 1610 KHz) located at known co-ordinates around the world
the Non-Directional Beacons (NDB) (190 to 550 KHz).

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2. Component Location

ADF - Component Location ** ON A/C NOT FOR ALL

FIN	FUNCTIONAL DESIGNATION	PANEL	ZONE	ATA REF
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2RP1	RECEIVER-ADF, 1	81VU	127	34-53-31
3RP1	ANTENNA-ADF LOOP AND SENSE, 1		240	34-53-11
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2RP2	RECEIVER-ADF, 2	82VU	128	34-53-31
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3RP2	ANTENNA-ADF LOOP AND SENSE, 2		240	34-53-11

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3. System Description

A. Principle
The principle of the ADF navigation is to determine the relative bearing of a selected ground station.
This is obtained by the combination of :

the signals from two loop and sense antennas positioned 90 deg. apart with
the signal from an omni-directional sense antenna. This signal is not affected by the relative bearing.
An external 96Hz signal modulates the composite signal which is processed in order to deliver the relative bearing.
An additional Morse signal is provided to identify the selected ground station.

B. System Architecture

ADF - Block Diagram ** ON A/C NOT FOR ALL

The ADF comprises one system which consists of :

one receiver 2RP1
one loop and sense antenna 3RP1.

In addition, the components given after control the system:

ADF - Control and Indicating ** ON A/C NOT FOR ALL

the Radio Management Panel 1 (RMP) 1RG1
the CAPT (F/0) Audio Control Panel (ACP) 2RN1 (2RN2)
the Multipurpose Control and Display Unit 1 (2) (MCDU) 3CA1 (3CA2)
the Flight Management and Guidance Computer 1 (2) (FMGC) 1CA1 (1CA2)
the Centralized Fault-Display Interface-Unit (CFDIU) 1TW
the Audio Management Unit (AMU) 1RN.

The Navigation Displays (ND) show the ADF data.

ADF - Block Diagram ** ON A/C NOT FOR ALL

The ADF comprises two independent systems. Each system consists of :

one receiver 2RP1 (2RP2)
one loop and sense antenna 3RP1 (3RP2)
one VOR/ADF/DME Radio Magnetic Indicator (VOR/ADF/DME RMI) 21FN.

In addition, the components given after control the system :

ADF - Control and Indicating ** ON A/C NOT FOR ALL

the Radio Management Panel 1(2) (RMP) 1RG1 (1RG2)
the CAPT (F/O) Audio Control Panel (ACP) 2RN1 (2RN2)
the Multipurpose Control and Display Unit 1(2) (MCDU) 3CA1 (3CA2)
the Flight Management and Guidance Computer 1(2) (FMGC) 1CA1 (1CA2)
the Centralized Fault-Display Interface-Unit (CFDIU) 1TW
the Audio Management Unit (AMU) 1RN.

The Navigation Displays (ND) show the ADF1 and ADF2 data.

ADF - Block Diagram ** ON A/C NOT FOR ALL

The ADF comprises one system which consists of :

one receiver 2RP1
one loop and sense antenna 3RP1
one VOR/ADF/DME Radio Magnetic Indicator (VOR/ADF/DME RMI) 21FN.

In addition, the components given after control the system:

ADF - Control and Indicating ** ON A/C NOT FOR ALL

the Radio Management Panel 1(2) (RMP) 1RG1 (1RG2)
the CAPT (F/O) Audio Control Panel (ACP) 2RN1 (2RN2)
the Multipurpose Control and Display Unit 1(2) (MCDU) 3CA1 (3CA2)
the Flight Management and Guidance Computer 1(2) (FMGC) 1CA1 (1CA2)
the Centralized Fault-Display Interface-Unit (CFDIU) 1TW
the Audio Management Unit (AMU) 1RN.

The Navigation Displays (ND) show the ADF data.

ADF - Block Diagram ** ON A/C NOT FOR ALL

The ADF comprises one system which consists of:

one receiver 2RP1
one loop and sense antenna 3RP1.

The second system is in space provision and consists of :

one loop and sense antenna 3RP2.

In addition, the components given after control the system:

ADF - Control and Indicating ** ON A/C NOT FOR ALL

the Radio Management Panel 1 (RMP) 1RG1
the CAPT (F/0) Audio Control Panel (ACP) 2RN1 (2RN2)
the Multipurpose Control and Display Unit 1 (2) (MCDU) 3CA1 (3CA2)
the Flight Management and Guidance Computer 1 (2) (FMGC) 1CA1 (1CA2)
the Centralized Fault-Display Interface-Unit (CFDIU) 1TW
the Audio Management Unit (AMU) 1RN.

The Navigation Displays (ND) show the ADF data.

C. Utilisation Technical Data

(1) Data display

ADF - Data and Warning Displays ** ON A/C NOT FOR ALL

(a) In ROSE and ARC modes
If you set the ADF/VOR/OFF switch on the EFIS control section of the Flight Control Unit (FCU) to ADF, this causes : display of the characteristics of the ADF 1 station in the L lower corner of the ND (item 3) :

type of station
shape of the associated bearing display
station identification or frequency
tuning mode (nothing : automatically tuned, M : manually tuned and R : if tuned by the RMP).

A single pointer on the heading dial shows the bearing of the ADF 1 (item 2).
All these data are shown in green except the tuning mode which is shown in white.

(b) In ROSE NAV and ARC modes
If you push the NDB pushbutton switch on the EFIS control section of the FCU, triangle symbols show the ADF stations (item 1).

(d) In case of ADF fault, a red ADF warning message is shown in place of the station characteristics.

(2) Data Display

ADF - Data and Warning Displays ** ON A/C NOT FOR ALL

(a) In ROSE and ARC modes
If you set the ADF/VOR/OFF switches on the EFIS control section of the FCU to ADF, this causes : display of the characteristics of the ADF 1 and/or 2 stations in the L and/or R lower corner of the ND (item 3) :

type of station
shape of the associated bearing display
station identification or frequency
tuning mode (nothing : automatically tuned, M : manually tuned and R : if tuned by the RMP).

A single pointer on the heading dial shows the bearing of the ADF 1, a double pointer that of the ADF 2 (item 2).
All these data are shown in green except the tuning mode which is shown in white.

(b) In ROSE NAV and ARC modes
If you push the NDB pushbutton switch on the EFIS control section of the FCU, triangle symbols show the ADF stations (item 1).

(d) In case of ADF 1 (2) fault, a red ADF warning message is shown in place of the station characteristics.

(3) On the VOR/ADF/DME RMI
If you set the VOR/ADF selector switches (item 4) to ADF, the RMI indicates the ADF bearings :

a single pointer indicates the ADF 1 bearing (item 5)
a double pointer indicates the ADF 2 bearing (item 6).

A warning flag comes into view to indicate system malfunction (item 7) . In this case, the related pointer is in the 3 o'clock position (item 8).
If No Computed Data (NCD), no warning flag comes into view but the related pointer stays in the 3 o'clock position.

(4) On the VOR/ADF/DME RMI
If you set one VOR/ADF selector switch (item 4) to ADF :

the related single pointer (item 5) or double pointer (item 6) indicates the ADF bearing.
A warning flag comes into view to indicate system malfunction (item 7). In this case, the related pointer is at the last valid position (item 8).
If No Computed Data (NCD), the warning flag comes into view and the related pointer stays at the position corresponding to the last correct data.

(5) On the VOR/ADF/DME RMI
If you set the VOR/ADF selector switches (item 4) to ADF, the RMI indicates the ADF bearings :

a single pointer indicates the ADF 1 bearing (item 5)
a double pointer indicates the ADF 2 bearing (item 6).

A warning flag comes into view to indicate system malfunction (item 7) . In this case, the related pointer is at the last valid position (item 8).
If No Computed Data (NCD), the warning flag comes into view and the related pointer stays at the position corresponding to the last correct data.

(6) Audio control

(a) The ADF receiver applies its audio output to the audio integrating system. This system controls and directs the output to the headsets and/or the loud speakers.
The AMU controls the audio level through the ACP.
On the ACP, the pilot must push the ADF1 pushbutton switch and adjust the related potentiometer to the correct audio level.

(b) Only with NDB stations modulated in A1 mode (in automatic or manual mode) it is necessary to select the BFO function on the MCDU in order to hear clearly its Morse identification signal.

you push the STBY NAV/ADF pushbutton switch
you push the STBY NAV/BFO pushbutton switch.

(d) It is possible to select the broadcast station on the RMP and the MCDU (manual mode only). In this case, the BFO selection is not necessary.

(e) With the ATIS message transmission by the NDB station, with the BFO is necessary to push the ON VOICE pushbutton switch on one ACP in order to hear clearly this information without Morse signal.

(7) Audio control

(a) The ADF receiver applies its audio output to the audio integrating system. This system controls and directs the output to the headsets and/or the loud speakers.
The AMU controls the audio level through the ACP.
On the ACP, the pilot must push the ADF1 (ADF2) pushbutton switch and adjust the related potentiometer to the correct audio level.

(b) Only with NDB stations modulated in A1 mode (in automatic or manual mode) it is necessary to select the BFO function on the MCDU in order to hear clearly its Morse identification signal.

you push the STBY NAV/ADF pushbutton switch
you push the STBY NAV/BFO pushbutton switch.

(d) It is possible to select the broadcast station on the RMP and the MCDU (manual mode only). In this case, the BFO selection is not necessary.

(e) With the ATIS message transmission by the NDB station, with the BFO active : it is necessary to push the ON VOICE pushbutton switch on one ACP in order to hear clearly this information without Morse signal.

(8) Audio control

(b) Only with NDB stations modulated in A1 mode (in automatic or manual mode) it is necessary to select the BFO function on the MCDU in order to hear clearly its Morse identification signal.

you push the STBY NAV/ADF pushbutton switch
you turn the outer knob of the dual selector knob to activate the BFO mode.

(d) It is possible to select the broadcast station on the RMP and the MCDU (manual mode only). In this case, the BFO selection is not necessary.

D. Warning

ADF - Data and Warning Displays ** ON A/C NOT FOR ALL

The warning related to the ADF is only the local warning shown on the NDs.
The warning is detected by the BITE function of the receiver.

ADF - Data and Warning Displays ** ON A/C NOT FOR ALL

The warnings related to the ADF(s) are only the local warnings shown on the NDs.
The warnings are detected by the BITE function of the receiver.

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4. Power Supply

ADF - Block Diagram ** ON A/C NOT FOR ALL

Energization of the system is through 115VAC 400 Hz buses :

115VAC SHED ESS BUS 801XP via circuit breaker 1RP1

115VAC BUS 2 202XP via circuit breaker 1RP2

The 115VAC ESS BUS 401XP energizes the VOR/ADF/DME RMI via circuit breaker 12FN.

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5. Component Description

A. ADF Receiver FIN: 2-RP-1 FIN: 2-RP-2

(1) Characteristics

Frequency range : 190 to 1799 KHz in 0.5 KHz steps
Electrical power supply: 115VAC, 400 Hz, 45 VA
Tuning accuracy: selected frequency plus or minus 250 Hz
ADF accuracy: plus or minus 2 deg.
Sensivity: 30 % modulation
ADF mode: 50 microV/m field strength at 400 Hz for 6 dB signal to noise ratio.

(2) External description
The ADF receiver conforms with the ARINC specification 600.
The case size is 2MCU.

(a) Receiver face

ADF - Receiver ** ON A/C NOT FOR ALL

The face of the receiver is fitted with a handle, one lug, a TEST pushbutton switch and two LEDs.
The name, color and function of the two LEDs are as follows:

LRU STATUS (red): indicates that a malfunction is detected during the self test of the ADF receiver.
LRU STATUS (green): indicates that no faults are detected during the self test of the ADF receiver.
CONTROL FAIL (red): indicates that an ARINC input data is faulty.

The back is equipped with one ARINC 600 size one connector which includes three plugs:

Top Plug (TP): connection with the automatic test circuit
Middle Plug (MP): connection with the antenna and peripheral circuits
Bottom Plug (BP): connection with the power supply circuit.

Index pin code is 05.

(3) Characteristics

Frequency range : 150 to 1799 KHz in 0.5 KHz steps
Electrical power supply: 115VAC, 400 Hz, 30 watts
Tuning accuracy: selected frequency plus or minus 250 Hz
ADF accuracy: plus or minus 2 deg.
Sensivity: 30 % modulation
ADF mode: 50 microV/m field strength at 400 Hz for 6 dB signal to noise ratio.

(4) External description

ADF - Receiver ** ON A/C NOT FOR ALL

The back of the ADF receiver is equipped with one ARINC 600 size one connector, which includes three plugs:

Top Plug (TP): is not used
Middle Plug (MP): used for aircraft connections ts
Bottom Plug (BP): used for input power.
The face of the receiver is fitted with a handle, two attaching parts, a TEST pushbutton switch and three LEDs.
The names, colors and functions of the three LEDs are as follows:

(a) ADF STATUS:

amber: indicates that the test is in progress
green: indicates that no faults are detected during the self-test sequence.

(b) CONTROL FAULT:

amber: indicates that the test is in progress
red: indicates invalid frequency input tuning words or no transmission
off: indicates that no faults are detected during the self-test sequence.

(5) Internal description
The receiver determines the relative bearing to any selected transmitter operating between 190 and 1799 KHz. This bearing data is converted into ARINC 429 format and transmitted through ARINC buses to the NDs via the DMCs. In addition the AM modulation of the carrier wave is detected and applied to the audio integrating system. The receiver is housed in an ARINC 2MCU case and consists of the following interconnected assemblies:

(a) An ARINC interconnect assembly which provides filtering against HIRF and noise entry or exit.

(b) A digital instrumentation assembly which contains the system processor and signal processor:

1 The function of the system processor is to:

format the ADF data from the signal processor into an ARINC 429 bearing word
provide frequency tuning for the ADF receiver
perform functional test and self-test functions
provide diagnostic data to the maintenance processor
transmit data generated by the system processor and maintenance processor
store calibration constants (as received from the signal processor) in the system processor Non-Volatile Memory during the calibration mode
monitor the power-down warning signal from the power supply to provide warm start capability
monitor system voltages and discretes for fault conditions.

2 The function of the signal processor is to:

compute and output, to the system processor, the ADF bearing derived from the ADF detector
determine the presence of the ADF detector signal and flag the bearing data accordingly
detect the presence of a 400Hz or 1020Hz identification tone (or BFO mode) and output a "tone present" discrete to the maintenance processor
monitor ADF signal level status and output maintenance data to the system processor
output sin mode and cosine mode to the loop modulators via their respective D/A converters
process the ADF detector signal to provide filtered and amplitude controlled audio information to the aircraft audio system.

(c) A maintenance processor assembly the primary function of which is the logging of maintenance information and secondarily, decoding the morse binary data stream into ASCII characters.

(d) A power supply assembly which provides +12VDC, -12VDC and -5VDC from 115VAC at 400Hz.

(e) A tuner/synthesizer assembly

1 The tuner combines the sense and loop signals from the antenna, amplifies and filters them and then provides the detected audio information to the signal processor.

2 The synthesizer receives frequency information from the system processor and provides fixed and variable oscillator signals for the mixers in the tuner.

(6) Operation

ADF Receiver - Simplified Block Diagram ** ON A/C NOT FOR ALL

The operation of the receiver is initiated when the desired frequency is selected by the FMGCs or RMPs.
Frequency and function data are received via an interface.
This data is used to activate the desired function, set the receive band and tune a Voltage Controlled Oscillator (VCO) for converting the received signal to the IF.
Sense and loop signals from the antenna are applied to the loop modulators where they are modulated with 95Hz control signals from the signal processor. The summed output of the loops is corrected for the antenna loop gain and phase and then summed with the sense channel.
The composite output of the summing circuit is passed through a band select filter, which output feeds the first mixer.
The VCO is mixed with the input to generate a first IF of 15MHz. The signal is filtered and amplified and then applied to the second mixer where 18.6MHz mixes it down to a second IF of 3.6Mhz. It is once again filtered and amplified before application to a coherent detector. The output of the coherent detector is used to derive the AGC control for the IF. The composite audio is sampled and processed by audio and bearing algorithms in a Digital Signal Processor (DSP) in the signal processor area. The DSP filters the audio, and sets the output level and returns it to an audio amplifier stage, and then to the aircraft audio system. The DSP also applies a separate narrow audio filter and then detects the audio tone for MORSE ident. This binary data stream is sent to the maintenance processor for decoding into ASCII characters.
The bearing is determined in the null-seeking algorithm by the DSP continuously adjusting the ratio of the 95Hz loop modulation applied to the sine and cosine modulators. When the ratio is properly adjusted, the amount of 95Hz present in the coherent detector output is minimized. The ratio of the loop modulation is then directly proportional to the raw bearing. The raw bearing is corrected for Quandrantal Error and calibration factors.
The signal processor then converts this corrected bearing to ARINC word format and relays it to the system processor for transmission on the ARINC bus.
In addition to its receiver control functions, the system processor continuously monitors receiver health and passes radio health information to the maintenance processor. It also initiates functional tests when conditions allow it.
The maintenance processor processes commands from the CFDIU and stores faults detected by the system processor. It also decodes the MORSE ident data stream passed by the signal processor.

(7) Internal description

ADF Receiver - Simplified Block Diagram ** ON A/C NOT FOR ALL

The ADF receiver includes:

an RF module,
a main processor assembly,
a power supply assembly,
a rear interconnect module,
a front panel display module,
a memory card interface module.

(a) RF module
The RF module contains receiver and synthesizer circuits to amplify and connvert the antenna derived sense, sine and cosine signals to baseband signals for digital signal processing.
The RF receiver receives three signals from the combined sense/loop antenna, sense signal from the sense portion of the antenna and sine and cosine signals from the two bar-loops.
The sense signal is coupled to a buffer amplifier that provides +4 to +6 dB gain and improves the voltage to noise figure of the receiver. The buffer amplifier also prevents loop modulation backward towards to sense antenna.
The sense signal is summed in quadrature with the 105 Hz phase modulated sine and cosine signals. This composite signal is then upconverted to 10.7 MHz where a cristal filter provides selectivity. The signal is then amplified and detected for processing by the digital signal processor.
The synthesiser provides local oscillator injection to upconvert the ADF RF signals to 10.7 MHz. The upconverted signal is passed through an IF filter and an IF amplifier. The signal is then down converted to 140 kHz. The 140 kHz IF signal is then amplified and sampled by the Analog/Didital (A/D) and sent to the DSP via the FIFO.
Tuning (band switching) is accomplished by utilizing a 7 - band RF filter in conjunction with a band switching circuit. Essentially the tuning range of the ADF receiver is separated into seven discrete bands.

(b) Main Processor Module
The Main Processor Board serves as the heart of the ADF reciver. The analog signals from the RF module are processed and used to generate the ADF audio and bearing outputs. All aircraft interfaces are controlled by this board. All information on the front panel display is provided by this board.
The board includes three major sections:

DSP section,
DP (microprocessor) section,
I/O section.

1 DSP section
The DSP section is used to process the analog outputs from the RF Module and to generate automatic gain control and other receiver commands as well as test signals to the RF Module.
The DSP performs the bearing computations, Automatic Gain Control (AGC), Audio Filtering, Morse Code Tone detection, part of the BITE monitoring and RF module control. The DSP programs the synthesizer using the data from the DP.
The composite ADF signal from the RF Module is digitized using an A/D converter. The A/D converter is also used to monitor signals from the BITE test points on the power supply voltages. The digitized data from the A/D converter is stored in a FIFO which is accessed by the DSP.
Programmable Logic Devices (PLD) are used by the DSP to generate the control signals for the ADF frequency synthesizer. A Digital/Analog (D/A) converter generates the AGC and test control signals for the RF Module. A second D/A converter generates the audio outputs which are amplified to provide up to 50mW into a load ranging from 200 Ohms to 600 Ohms.
A D/A converter generates the AGC, lateral and longitudinal modulations as well as the Audio signal.
Data is exchanged with the CPU Section through a dual-port RAM, providing maximum throughput of both processors.
The DSP provides the DP with the ADF bearing outputs periodically (every 50 ms) via the shared memory interface. The Main DSP also provides morse code report via the shared memory interface. In addition the DSP provides the audio outputs via the D/A.

2 DP section (Intel 80486)
The DP section is used to process the BIT data from the DSP section, to provide information to the front panel display and to provide the data and control signals to the I/O section. The microprocessor in the DP section controls all major functions of the ADF. Programmable Logic Devices serve as the microprocessor controller and provide the interfaces to the memory devices, the data recorder/data loader flash card, and the front panel display driver.
The DP receives the ADF bearing reports from the DSP every 50 ms. The DP sends the ADF receiver frequency band select, operational mode select and receiver synthesizer tuning code to the DSP upon the receipt of an external frequency change command. The DP performs the QEC and TOP/BOTTOM compensation on the bearing data received from the DSP prior to outputing the bearing data to external systems.
Data is exchanged with the DSP section through a dual-port RAM.

3 I/O section
The I/O section provides the interfaces with other aircraft systems including the centralized Fault Display Interface Unit (CFDIU), Control Panel(s), displays and the AFCS.
ARINC 429 inputs from the data loader, CFDIU and the tuning control panel(s) are processed by the ARINC 429 Large Scale Integrated (LSI). This LSI also provides the ARINS 429 data loader, CFDIU and deviation outputs. External buffers are used to satisfy the ARINC 429 characteristics for the transmitters.
All discrete inputs external to the ADF Receiver are processed by the I/O section. This section also generates the external discrete outputs.
The I/O section also contains an RS-232C test interface.

(c) Power Supply Module
The 115 VAC, 400 Hz aircraft power is converted by the Power Supply into the DC operating voltages required by the various modules within the ADF receiver. A self-contained, high efficiency switching power supply is used to minimize power dissipation.
Five voltages (+5, +12, -12, +20 and +24V) are supplied and a Power Down Interrupt that provides avanced notice of a power loss allowing the processors to temporarily retain their status.
A switching circuitry is provided for the power supply to switch its operating frequency in order to prevent a degradation of the receiver sensitivity.

(d) HIRF/Rear Interconnect Module
The signal and power cables are on the rear interconnect located inside this High Intensity Radiated Field (HIRF) compartment. The filtered lines are then fed to the appropriate points in the unit. The filtering is accomplished using discrete and distributed shunt capacitance for HIRF filtering. The series resistance, required to limit lightning-induced currents, also forms a series element to HIRF filtering.

(e) Front Panel Display
The front panel contains a low-power Liquid Crystal Display (LCD) used as a fault display and as an operator interface during certain modes and display drivers. The front panel display also provides user interfaces for test and troubleshooting.

(f) Memory Card Interface Module
The ADF receiver is provided with an interface for a Personal Computing Memory Card Interface Adapter (PCMCIA) "flash card" which gives the capability to record data or be configured for read only memory (means to load new software without opening the unit to replace Programmable Read Only Memory (PROM), maintenance and problem installations).

(8) Digital outputs
This table contains all the output parameters in the digital form.

----------------------------------------

! LABEL ! PARAMETER DEFINITION !

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! 032 ! ADF FREQUENCY !

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! 162 ! ADF BEARING !

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! 254 ! ADF IDENTIFIER WORD 1 !

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! 255 ! ADF IDENTIFIER WORD 2 !

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! 377 ! EQUIPEMENT IDENTIFIER !

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! 356 ! MAINTENANCE STATUS !

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B. Loop and Sense Antenna

ADF - Antenna

The combined loop and sense antenna operates in the 190 to 1750 kHz frequency range and consists of the following components enclosed in a fiberglass housing:

a vertically polarized sense antenna which is omnidirectional in the horizontal plane
two horizontally polarized orthogonal loop antennas which are directional in the horizontal plane
a test loop which enables a self-test of the antenna
a printed circuit board which contains three pre-amplifiers used to amplify the loop and sense antennas signals. The pre-amplifiers are energized by plus or minus 12VDC form the ADF receiver.

The output impedance of the antenna is 78 Ohms and the Voltage Standing Wave Ratio (VSWR) 1.2:1.

** ON A/C NOT FOR ALL

6. Operation

ADF - Block Diagram ** ON A/C NOT FOR ALL

The FMGC 1 sends a management bus to the ADF receiver 1 through the RMP 1.
In normal operation, the FMGC 1 tunes the ADF receiver 1 either automatically or manually by means of the MCDU. In this case, the RMP 1 operates as a relay which sends the frequency information from the FMGC 1 to the ADF receiver 1.
By a second port, the ADF receiver 1 receives a second management bus directly from the FMGC 2. The FMGC 2 becomes active when the ADF receiver 1 receives a fault signal from the FMGC 1.
With RMP 1 internal faults the RMP 1 is transparent to data and discrete from the FMGC 1.
In emergency configuration (fault of the FMGC 1 and 2), the RMP 1 can control the ADF receiver 1 after ON NAV mode selection.

ADF - Frequency Selection in Emergency Mode ** ON A/C NOT FOR ALL

ADF - Block Diagram ** ON A/C NOT FOR ALL

NOTE: The two ADF systems are independent. The operating mode is identical for ADF 1 and ADF 2.

The FMGC 1 sends a management bus to the ADF receiver 1 through the RMP1.
In normal operation, the FMGC 1 tunes the ADF receiver 1 either automatically or manually by means of the MCDU. In this case, the RMP 1 operates as a relay which sends the frequency information from the FMGC 1 to the ADF receiver 1.
By a second port, the ADF receiver 1 receives a second management bus directly from the FMGC 2. The FMGC 2 becomes active when the ADF receiver 1 receives a failure signal from the FMGC 1.
With RMP 1 internal failures the RMP 1 is transparent to data and discrete from the FMGC 1.
In emergency configuration (failure of the FMGC 1 and 2), the RMP 1 can control the ADF receiver 1 after ON NAV mode selection.
In emergency configuration (failure of the FMGC 1 and 2), the RMP 2 can control the ADF receiver 2 after on NAV mode selection.

ADF - Frequency Selection in Emergency Mode ** ON A/C NOT FOR ALL

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7. Test

A. Maintenance Test

ADF - Maintenance Test Procedure ** ON A/C NOT FOR ALL

It is possible to do the maintenance tests with the Centralized Fault Display System (CFDS).
The primary components of the CFDS are :

the MCDU
the CFDIU
the Built-In Test Equipment (BITE) internal to the ADF receiver.

It is possible to perform these tests on the ground only.
The access to the ADF 1 menu is through :

selection of the SYSTEM REPORT/TEST item on the CFDS menu
then, selection of the relevant ADF on the NAV menu.

The test sequence starts when you push the line key adjacent to the TEST indication on the ADF1 menu.

ADF - Maintenance Test Procedure ** ON A/C NOT FOR ALL

It is possible to do the maintenance tests with the Centralized Fault Display System (CFDS).
The primary components of the CFDS are :

the MCDU
the CFDIU
the Built-In Test Equipment (BITE) internal to the ADF receiver.

It is possible to perform these tests on the ground only.
The access to the ADF 1 menu is through :

selection of the SYSTEM REPORT/TEST item on the CFDS menu
then, selection of the relevant ADF on the NAV menu.

A self-test of the system causes the receiver to transmit a test signal to the VOR/ADF/DME RMI and ND.
On the VOR/ADF/DME RMI, if you set the VOR/ADF selector switches (item 4) to ADF.
The test sequence starts when you push the line key adjacent to the TEST indication on the ADF1 menu.

ADF - Maintenance Test Procedure ** ON A/C NOT FOR ALL

It is possible to do the maintenance tests with the Centralized Fault Display System (CFDS).
The primary components of the CFDS are :

the MCDU
the CFDIU
the Built-In Test Equipment (BITE) internal to the ADF receiver.

It is possible to perform these tests on the ground only.
The access to the ADF 1 (2) menu is through :

selection of the SYSTEM REPORT/TEST item on the CFDS menu
then, selection of the relevant ADF on the NAV menu.

B. CFDIU Interface

ADF - Block Diagram ** ON A/C NOT FOR ALL

(1) BITE description
The BITE facilitates maintenance on in-service aircraft.
It detects and identifies a failure related to the ADF system.
The BITE of the ADF receiver is connected to the CFDIU (Ref. AMM D/O 31-32-00-00).
The unit tested is the ADF receiver.
The BITE:

transmits continuously ADF system status and its identification message to the CFDIU
memorizes the failures which occurred during the last 63 flight segments
monitors data inputs from the various peripherals (RMP and CFDIU)
transmits to the CFDIU the result of the tests performed and self-tests
can communicate with the CFDIU through the menus.

The BITE can operate in two modes:

the normal mode
the menu mode.

(a) Normal mode
During the normal mode the BITE monitors cyclically the status of the ADF system. It transmits its information to the CFDIU during the concerned flight.
In case of fault detection the BITE stores the information in the fault memories.
These items of information are transmitted to the CFDIU every 50 - 250 ms by an ARINC 429 message with label 356.

(b) Menu mode:
The menu mode can only be activated on the ground.
This mode enables communication between the CFDIU and the ADF receiver BITE by means of the MCDU.
The ADF menu mode is composed of:

LAST LEG REPORT
PREVIOUS LEGS REPORT
LRU IDENTIFICATION
GROUND SCANNING
TROUBLE SHOOTING DATA
CLASS 3 FAULTS
GROUND REPORT
TEST.

(2) Interactive function
The interactive mode can be activated on the ground only, using the line key adjacent to the ADF indication on the SYSTEM REPORT/TEST page of any MCDU (Ref. 22-82-00).
This mode enables communication between the CFDIU and the BITE of the ADF receiver by means of the MCDU.

ADF - Maintenance Test Procedure ** ON A/C NOT FOR ALL

The interactive mode is composed of:

LAST LEG REPORT:
This report contains the fault messages related to the external or internal failures (class 1 and 2) recorded during the last flight leg.
ADF - Last Leg Report, Previous Legs Report and LRU IDENT ** ON A/C NOT FOR ALL
ADF - Last Leg Report, Previous Legs Report and LRU IDENT ** ON A/C NOT FOR ALL
PREVIOUS LEGS REPORT:
This report contains the fault messages related to the external or internal failures (class 1 and 2) recorded during the previous 63 flight legs.
ADF - Last Leg Report, Previous Legs Report and LRU IDENT ** ON A/C NOT FOR ALL
ADF - Last Leg Report, Previous Legs Report and LRU IDENT ** ON A/C NOT FOR ALL
LRU IDENTIFICATION:
Allows to display the P/N and the S/N of the equipment.
ADF - Last Leg Report, Previous Legs Report and LRU IDENT ** ON A/C NOT FOR ALL
ADF - Last Leg Report, Previous Legs Report and LRU IDENT ** ON A/C NOT FOR ALL
GROUND SCANNING:
ADF - GROUND SCANNING and Trouble Shooting Data ** ON A/C NOT FOR ALL
ADF - GROUND SCANNING and Trouble Shooting Data ** ON A/C NOT FOR ALL
Based on the monitoring and fault analysis during flight, provides information of the failures detected while using this function.
By pressing the line key adjacent to the failure message, the operator is allowed to the corresponding Trouble Shooting Data. The peripheral monitoring and ADF internal cyclic tests are used to detect transient failures.
TROUBLE SHOOTING DATA
ADF - GROUND SCANNING and Trouble Shooting Data ** ON A/C NOT FOR ALL
ADF - GROUND SCANNING and Trouble Shooting Data ** ON A/C NOT FOR ALL
Provides correlation parameters and snapshot data concerning the failure displayed in the LAST LEG REPORT and PREVIOUS LEGS REPORT.
CLASS 3 FAULTS
ADF - CLASS 3 FAULTS and Ground Report
Allows to display the class 3 faults recorded during the last flight leg.
GROUND REPORT
ADF - CLASS 3 FAULTS and Ground Report
Allows to present the class 1, 2 or 3 internal failures detected on ground.
These failures differ from those displayed on the LAST LEG REPORT and CLASS 3 FAULTS.
By pressing the line key adjacent to the failure message, the operator is allowed to access to the corresponding Trouble Shooting Data.
TEST
ADF - TEST
Allows a check of the correct operation of the ADF on the ground.
This test can be performed by:
either selecting the test function on the face of the ADF receiver by pressing the TEST pushbutton switch
or through the Centralized Fault Display System (CFDS) by selecting, on the MCDU, the test function on the ADF main menu page.

All the information displayed on the MCDU during the BITE TEST configuration can be printed by the printer (Ref. AMM D/O 31-35-00-00).

C. Power-up Tests Initialization and Cockpit Repercussions

(1) Conditions of power-up tests initialization

How long the computer must be de-energized: 2 s.
A/C configuration:
- whatever the A/C configuration on ground

(2) Progress of power-up tests

(a) Duration: 2 s.

(b) Cockpit repercussions directly linked to power-up test accomplishment (some other repercussions may occur depending on the A/C configuration but these can be disregarded):

if ADF selected on FCU
- ND
ADF 1 in red
if ADF RMI option available
- ADF RMI display
ADF flag during 2 s.

(3) Results of power-up tests
(cockpit repercussions, if any, in case of tests pass/tests failed).

(a) Tests pass:

if ADF selected on FCU
- ND
ADF 1 in green
if ADF RMI option available
- ADF RMI display
ADF flag no longer displayed

(b) Tests failed:

if ADF selected on FCU
- ND
ADF 1 red indications flash
if ADF RMI option available
- ADF RMI display
ADF flag

(4) Conditions of power-up tests initialization

How long the computer must be de-energized: 2 s.
A/C configuration:
- whatever the A/C configuration on ground

(5) Progress of power-up tests

(a) Duration: 2 s.

(b) Cockpit repercussions directly linked to power-up test accomplishment (some other repercussions may occur depending on the A/C configuration but these can be disregarded):

if ADF selected on FCU
- ND
ADF 1 or 2 in red
if ADF RMI option available
- ADF RMI display
ADF flag during 2 s.

(6) Results of power-up tests
(cockpit repercussions, if any, in case of tests pass/tests failed).

(a) Tests pass:

if ADF selected on FCU
- ND
ADF 1 or 2 in green
if ADF RMI option available
- ADF RMI display
ADF flag no longer displayed

(b) Tests failed:

if ADF selected on FCU
- ND
ADF 1 or 2 red indications flash
if ADF RMI option available
- ADF RMI display
ADF flag

[Rev.10 from 2021] 2026.04.02 06:23:33 UTC