AUTOMATIC DIRECTION FINDER (ADF) – GENERAL
The ADF system supplies data for in-flight navigation, terminal navigation,
and area guidance. A narrow band mode is used to reduce noise during
navigation. A wide band mode is used to improve clarity when listening to
voice signals.
The optimal audio and bearing reception are obtained by selecting the most
appropriate of the following models:
• ANTENNA (ANT): receives ADF station signal and does not compute
bearing
• ADF: receives ADF station signal and computes relative bearing to
station
• VOICE: opens IF bandwidth for improved audio fidelity and does not
compute bearing
• BEAT FREQUENCY OSCILLATOR (BFO): adds a beat frequency
oscillator for reception of CW signals.
The ADF audio is transmitted from the digital audio bus to each audio panel
in the system.
The ADF main components are
• one ADF module (installed is in the MRC 2 pilot side)
• one ADF antenna
When the second ADF is installed, it is identified as ADF 1 and the originally
installed ADF is identified as ADF 2 and is installed in the MRC 1 (copilot
side). The second ADF antenna is installed on the bottom center fuselage,
behind the first ADF antenna.
The pages associated with the ADF system are shown in the figure.
ADF TUNING AND MODE SELECTION
ADF tuning and selection of mode of operation can only be performed via
the MCDUs, page RADIO 2/2.
ADF is not available in case of BKUP RADIO control.
See chapter 23-00 for further details on tuning and memory setting.
ADF INDICATIONS
ADF indications are provided via the Bearing Pointers on the HSI.
In case of single ADF installation, both Bearing Pointers can be used to
display ADF bearing.