CHAPTER 34 – NAVIGATION

SECTION 34-53 - AUTOMATIC DIRECTION FINDER (ADF) SYSTEM DESCRIPTION The Automatic Direction Finder (ADF) system supplies the relative bearing data from a ground station for in-flight navigation, terminal navigation, and area guidance. This data gives the aircraft direction to a ground station with relation to the heading. The ADF receiver module, installed in the MRC2, receives RF signal from the ADF antenna, compute the relevant information and sends its data to the NIM. The NIM sends this NAV data on the ASCB-D bus to the NICs in the MAUs and to the EDS. The ADF data, received by NICs, is provided to the FMS processor modules through the MAU backplanes. The FMS uses NAV data from the ADF system to do its NAV functions. The electronic display system (EDS) shows ADF data that gives the radio bearing relative to the aircraft heading. The MRC2, also, transmits the ADF audio signals through the digital audio bus to each audio panel in the audio system. The ADF system uses two bandwidths: − A narrow band mode to reduce noise during navigation − A wideband mode to improve the quality of voice signals. The ADF system is composed by the components that follow: − DF-855 Automatic Direction Finder (ADF) Module − AT-860 Automatic Direction Finder (ADF) Antenna DF-855 ADF Module The ADF module is installed in the MRC2, is powered by +28 V dc, and supplies +15 V dc to the amplifier in the ADF antenna. The ADF module supplies steering data to low-frequency transmitters (beacons) with set frequencies from 190 to 400 kHz, and 1600 to 1799 kHz. It also supplies steering data to the following stations: − Broadcast Stations that Operate with Amplitude Modulation (AM) − Marine Stations that Operate in the Frequency Range of 100 to 190 kHz − Stations on the High Frequency (HF) Distress Frequency of 2182 kHz. The ADF module provides the relative bearing data to the NIM of the MRC2 through the internal bus, but it is also able to supply data to external users on the following way: − as ARINC-407 synchro data, − as direct current (dc) sine/cosine data, and − as RS-422 data. The ADF module has a mute (cancel) function that cancels the radio interference caused by HF signals transmitted from the aircraft. (This interference can cause some avionics to show incorrect ADF bearing indications).

AT-860 ADF Antenna The ADF antenna system contains an internal sense antenna, sine/cosine loop antennas, an amplifier, and a self-test function. The sense antenna is a vertically-polarized antenna that receives the AM audio signals. The sine/cosine loop antennas are horizontally-polarized, perpendicular antennas that receive the relative bearing signals. The amplifier increases the input signals from the internal antennas. The self-test function does a test of the ADF system components. The ADF antenna has a coaxial connector that connects to the ADF module. The antenna is installed on the bottom center outer fuselage. OPERATION The ADF system operates in the frequency range of 190.0 to 1799.5 kHz in increments of 500 Hz (for usual operation). It also tunes frequencies between 100 and 190 kHz, and monitors the maritime emergency frequencies between 2181 and 2183 kHz. In case of an airborne HF radio starts to transmit, the ADF module holds the ADF bearing pointer. If the HF radio transmits continuously for more than 5 seconds, the electronic ADF bearing pointer, shown on the PFD, goes out of view. These condition continues until the HF radio stops in order to prevent possible errors caused by bearing indications that are not accurate. The following table shows the four modes of operation for the ADF system.

MODE DESCRIPTION ANT (antenna) The system receives the ADF signals but does not

calculate the relative bearing. Audio sensitivity and range are set to maximum.

ADF The system receives the ADF signals and calculates the relative bearing. There is some decrease of received audio range and sensitivity.

BFO (beat frequency oscillator) The system receives the continuous wave (CW) signals. The system uses a beat frequency oscillator (BFO) to sense these signals.

VOICE The system increases the intermediate frequency (IF) bandwidth of the ADF module to make the quality of the ADF audio signals better. This mode does not supply bearing.

The VOICE mode supplies high quality audio signals for the headsets and flight compartment speakers. The high quality audio is a result of the wider bandwidth available in the VOICE mode. To find the direction to the ADF station, narrow band reception is necessary to increase the bearing accuracy. Because of the wider bandwidth, it is possible to hear BFO interference when the system monitors different ADF stations that are less than 3 kHz apart. To prevent this interference, use the ANT mode. CONTROLS AND INDICATORS The bearing data from the helicopter, provided by the Automatic Direction Finder (ADF2) over the ASCB-D, is shown on the PFD. This data is shown on the PFD by the diamond pointer when selected by the Diamond Bearing 2 Button of the Display Controller.

ADF Tuning Function The ADF tuning function is done with the MCDU through the ASCB-D, in case of ASCB-D failure a backup MCDU tuning mode lets the pilot or copilot tune the on-side COM and NAV through a direct ARINC 429 link from the MCDU to the radios. Because of this, and having the only ADF2 system installed onboard, during tuning backup mode the ADF system in not available. ADF System Operation with the Multifunction Control Display Unit (MCDU) The MCDU is the primary control unit for the PRIMUS EPIC® radio system. The MCDU controls the operative mode and frequency tune for the ADF2 system through the pages as follows:

1. RADIO 2/2: RADIO 2/2 page displays the radio data for the systems ADF2, COM radios, NAV radios and NAV/COM radios.

2. ADF 2: The ADF2 page displays the active, preset, and selected memory frequencies for the automatic direction finder, the controls for the active mode (antenna or ADF) and the beat frequency oscillators (BFO) setting (ON or OFF). It is also used to access the ADF memory pages.

3. ADF MEMORY: The ADF MEMORY 1/2 and ADF MEMORY 2/2 pages are utilized to store up to 12 ADF memories channels each one having an own associated frequency. In addition to entering or dialing–in frequencies for each memory location, a text label of up to 8 characters can be entered for each stored frequency. The default label for each memory is MEMORY, a dash, and the memory number, with the memory number always on the outboard edge of the display.

CAPTIONS No-one cautions message is available for the CAS window in the event of ADF system failure. Acknowledgement of a not availability of the ADF bearing data or ADF system failure occurs as follows: − ADF bearing pointer frozen: If the onboard HF radio starts to transmit. − ADF bearing pointer out of view: in case of ADF failure or if the onboard HF radio transmits

continuously for more than 5 seconds. LEADING PARTICULARS DF-855 Automatic Direction Finder (ADF) Module − Power Requirements: 28.0 V dc nominal, 30.3 V dc maximum, 22 V dc minimum − Circuit Breaker: 28 V dc 3.0 amps − Types of Reception: CW, AM − Frequency Range: 100.0 to 1799.5 kHz in 0.5 kHz steps − Intermediate Frequencies (IF):

• First IF: 10.7 MHz • Second IF: 4.3 MHz

− Bandwidth: • ANT, ADF, and BFO Modes: ≤ 2.8 kHz at six dB, ≤ 10 kHz at 80 dB • Voice Mode: ≥ 8.0 kHz at three dB, ≤ 26 kHz at 40 dB

− Sensitivity : • ANT Mode : Better than 50 mV/meter for six dB S + N/N for 400 Hz, 30%modulation

• ADF Mode : Better than 100 mV/meter for six dB signal to noise ratio for 400 Hz, 30% modulation

• BFO Mode : Better than 70 mV/meter for six dB signal to noise ratio for 400 Hz, 30% modulation

− Spurious Response: At least 80 dB below the desired response at all frequencies − Audio Output: 100 mW into a 600 load with < 10% distortion − Audio Frequency Response:

• ANT, ADF, and BFO modes: Not more than ±3 dB from 350 to 1100 Hz • Voice Mode: Not more than ±4 dB from 350 to 3200 Hz

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A

A

A

MODULAR RADIOCABINET #2 (MRC2)

ADF 2MODULE

34-53-03-002

Honeywell Honeywell Honeywell

Honeywell Honeywell

Hon

eyw

ell

ADFANT

DMEANT

TOPANT

MKR

GS

VIL

BOTANT

VHFCOMANT

MRC

CAPTIVE SCREWSADF MODULE HANDLE

WRIST STRAP SOCKET

ELECTRICAL CONNECTOR

ADF MODULE

BACKSHELL ATTACHMENT SCREW

ADF ANTENNA CONNECTOR

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ADF ANTENNA

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ADF ANTENNA

SCREW

GASKET

ADF ANTENNA CONNECTOR

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MCDUCPLT

MCDUPLT

PFDCPLT

PFDPLT

MAU1

MAU2

ADFAIR

MODULE

ADFMODULE

ADFANTENNA

ADF AUDIO OUT +15 Vdc PWR

LOOP AMP. ENABLE

ADF SIN/COS MODULAT.

ANT. TEST ENABLE

RF

28 Vdc PWR

RCB

+28VdcMAIN 2

NAV/COMADF

NIM NIM

CPLT AUDIOPANEL

PLT AUDIOPANEL

429 429

DIGITAL AUDIO BUSES

ASCB-D

DIGITAL MIC BUSES

MRC 1 MRC 2

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N33

30W

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6

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18 2040

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VOR GS 22.00150 ROL PIT 750

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AHRS1 ADS2

1210

IGS110 12.50 IN

2

1

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2

VTA

63 63 100PI

FUEL KG

FF KPH

NRNF NF

TQ TQ

APP

KDVT

DR

1.7 NM

MSG

1+22ETE

VOR1

ADF2

600

500

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118.03 109.05 3180 118.03COM1 NAV1 XPDR COM2

MAN

MAN

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IDLE

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1CASMSCP

15

N33

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3

63 63 100PI

FUEL KG

FF KPH

NRNF NF

TQ TQ

APP

KDVT

DR

1.7 NM

MSG

1+22ETE

VOR1

ADF2

600

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118.03 109.05 3180 118.03COM1 NAV1 XPDR COM2

MAN

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FAIL

IDLE

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1CASMSCP

15

VOR2/ADF2 BEARING POINTER SOURCE INDICATION

ADF2 BEARING POINTER

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N33

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24

21S

15

12E

6

3

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VOR GS 22.00150 ROL PIT 750

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10

AHRS1 ADS2

1210

IGS110 12.50 IN

2

1

1

2

VTA

63 63 100PI

FUEL KG

FF KPH

NRNF NF

TQ TQ

APP

KDVT

DR

1.7 NM

MSG

1+22ETE

VOR1

ADF2

600

500

400

250

200

150

300

118.03 109.05 3180 118.03COM1 NAV1 XPDR COM2

MAN

MAN

FAIL

IDLE

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1CASMSCP

15

N33

30W

24

21S

15

12E

6

3

63 63 100PI

FUEL KG

FF KPH

NRNF NF

TQ TQ

APP

KDVT

DR

1.7 NM

MSG

1+22ETE

VOR1

ADF2

600

500

400

250

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150

300

118.03 109.05 3180 118.03COM1 NAV1 XPDR COM2

MAN

MAN

FAIL

IDLE

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1CASMSCP

15

VOR2/ADF2 BEARING POINTER SOURCE INDICATION

ADF2 BEARING POINTER

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N33

30W

24

21S

15

12E

6

3

160

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18 2040500

VOR GS 22.00150 ROL PIT 750

20

20

10

10

20

20

10

10

AHRS1 ADS2

1210

IGS110 12.50 IN

2

1

1

2

VTA

63 63 100PI

FUEL KG

FF KPH

NRNF NF

TQ TQ

APP

KDVT

DR

1.7 NM

MSG

1+22ETE

VOR1

ADF2

600

500

400

250

200

150

300

118.03 109.05 3180 118.03COM1 NAV1 XPDR COM2

MAN

MAN

FAIL

IDLE

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600 600

100 100

1CASMSCP

15

N33

30W

24

21S

15

12E

6

3

63 63 100PI

FUEL KG

FF KPH

NRNF NF

TQ TQ

APP

KDVT

DR

1.7 NM

MSG

1+22ETE

VOR1

ADF2

600

500

400

250

200

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300

118.03 109.05 3180 118.03COM1 NAV1 XPDR COM2

MAN

MAN

FAIL

IDLE

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1CASMSCP

15

VOR2/ADF2 BEARING POINTER SOURCE INDICATION

ADF2 BEARING POINTER

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BRG NAV

ALT SEL BARO

HSI

PRV

MAP

LNAV

VX

BRG

DIAMOND BEARING 2POINTER SOURCE SELECTOR

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PERF

MENU

NAV PREV

NEXT

FPL PROG DIR

RADIO

PERF

MENU

NAV PREV

NEXT

FPL PROG DIR

RADIO

PERF

MENU

NAV PREV

NEXT

FPL PROG DIR

RADIO

PERF

MENU

NAV PREV

NEXT

FPL PROG DIR

RADIO

PERF

MENU

NAV PREV

NEXT

FPL PROG DIR

RADIO

R A D I O 2 / 2 R A D I O 1 / 2

A D F 2

A D FM E M O R Y 1 / 2

A D FM E M O R Y 2 / 2

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PERF

MENU

NAV PREV

NEXT

FPL PROG DIR

RADIO

PERF

MENU

NAV PREV

NEXT

FPL PROG DIR

RADIO

PERF

MENU

NAV PREV

NEXT

FPL PROG DIR

RADIO

PERF

MENU

NAV PREV

NEXT

FPL PROG DIR

RADIO

PERF

MENU

NAV PREV

NEXT

FPL PROG DIR

RADIO

R A D I O 2 / 2 R A D I O 1 / 2

A D F 2

A D FM E M O R Y 1 / 2

A D FM E M O R Y 2 / 2

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PERF

MENU

NAV PREV

NEXT

FPL PROG DIR

RADIO

PERF

MENU

NAV PREV

NEXT

FPL PROG DIR

RADIO

PERF

MENU

NAV PREV

NEXT

FPL PROG DIR

RADIO

PERF

MENU

NAV PREV

NEXT

FPL PROG DIR

RADIO

PERF

MENU

NAV PREV

NEXT

FPL PROG DIR

RADIO

R A D I O 2 / 2 R A D I O 1 / 2

A D F 2

A D FM E M O R Y 1 / 2

A D FM E M O R Y 2 / 2

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PERF

MENU

NAV PREV

NEXT

FPL PROG DIR

RADIO

R A D I OV O I C E A D F 2

6 0 0 . 0

3 2 6 . 0

2 / 2

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PERF

MENU

NAV PREV

NEXT

FPL PROG DIR

RADIO

A D F 2A C T I V E

P R E S E T

M E M T U N E

A D F

3

2 2 4 . 0

1 2 9 9 . 5

M E M O R Y R A D I O 2 / 2

S D L N D B

6 0 0 . 0

1 / 1

A N T E N N A B F O V O I C E

M O D E

34-53-03-007

PERF

MENU

NAV PREV

NEXT

FPL PROG DIR

RADIO

A D F M E M O R Y

A D F 2

1 - M E M O R Y

2 - M E M O R Y

3 - M E M O R Y

9 6 0 . 0

2 2 4 . 0

1 0 9 2 . 0

R A D I O 1 / 2

1 1 2 3 . 0

1 / 2

A D F 2

M E M O R Y - 4

M E M O R Y - 5

M E M O R Y - 6

NOTE: ADF MEMORY 2 / 2 page is the same as ADF MEMORY 1 / 2 page. The only difference is the locations numbered from 7 to 12.