automatic direction finder

automatic direction finder:

see radio rangeradio range,
geographically fixed radio transmitter that radiates coded signals in all directions to enable aircraft and ships to determine their bearings. An aircraft or ship can determine its line of position and drift if it knows its bearing relative to the radio transmitter
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Automatic Direction Finder

 

an aircraft radio direction finder for the automatic location of a bearing on transmitting ground stations. It usually consists of a receiver-indicator device coupled with a tracking system and two antennas—a directional loop and a nondirectional single wire antenna.

The signals from the radio station on which a bearing is being taken are received by both antennas and combined: the signal from the loop is switched with the frequency of a reference generator, producing an amplitude-modulated voltage at the receiver input. By comparing the voltages at the outputs of the receiver and the reference generator, an error signal is produced and then fed to the tracking system. The tracking system automatically rotates the loop to the position of minimum signal, which coincides with the bearing of the radio station. Sensors detect the angle of rotation of the loop and transmit it to an indicator with a pointer showing the relative angle of the radio station, that is, the angle between the longitudinal axis of the aircraft and the direction to the radio station.

Automatic direction finders generally operate with non-directional radio beacons, less often with other types, such as radio broadcast stations. Such devices make it possible to guide aircraft to the vicinity of an airfield, make a landing approach, and solve other navigational problems.

M. M. RAICHEV

automatic direction finder

[¦ȯd·ə¦mad·ik di′rek·shən ‚fīnd·ər]
(electronics)
A direction finder that without manual manipulation indicates the direction of arrival of a radio signal. Abbreviated ADF. Also known as radio compass.

automatic direction finder (ADF)

automatic direction finder (ADF)click for a larger image
Equipment to determine the direction from which an electromagnetic signal is being generated. It can either be airborne or ground-based equipment. It operates in medium or low frequencies, consists of basically a loop aerial, and gives the null position of the transmitter. To remove 180° ambiguity, a sense aerial is used. The commonest air-interpreted ADF is the one that utilizes a ground-based transmitting station called an NDB (nondirectional beacon).
References in periodicals archive ?
The selected Rockwell Collins baseline avionics package also includes Automatic Direction Finder, Distance Measuring Equipment, High Speed Data Radio, Very High Frequency Transceiver and Omnidirectional Radio.
Full suite of avionics sensors includes Rockwell Collins ADF-900 Automatic Direction Finder, DME-2100 Distance Measuring Equipment, VHF-2100 Transceiver, HFS-900D Radio and VOR-900 Omnidirectional Radio.
Also included is Collins' Flight2 6 x 8-inch Multi-Function Displays and AN/ARC-210 radios, SAT-2000, multimode receivers, automatic direction finder and high frequency data link upgrades.
Mezen Arkhangelsk region" in terms of construction and installation work for the installation of the drive stations and automatic direction finder.
Additional avionics include SAT-2000, multimode receivers, automatic direction finder and high frequency data link upgrades.
Other Rockwell Collins avionics systems selected by China Southern include its Traffic and Collision Avoidance System (TCAS II), SATCOM, ADF-900 Automatic Direction Finder, DME-900 Distance Measuring Equipment, HFS-900D High Speed Data Radio, LRA-900 Low-range Altimeter and VOR-900 Omnidirectional Radio.
China Southern also selected the following sensors: ADF-900 Automatic Direction Finder, DME-900 Distance Measuring Equipment, HFS-900D High Speed Data Radio, VHF-2100 Very High Frequency Transceiver, CPL-920D Coupling Unit and VOR-900 VHF Omnidirectional Radio.
ADF-900 Automatic Direction Finder, CPL-920D High Frequency Digital Antenna Coupler, DME-900 Distance Measuring Equipment, HFS-900D High Speed Data Radio, LRA-900 Low-range Radio Altimeter, PAU-700 Passenger Address Amplifier, VHF-2100 Very High Frequency Transceiver, VOR-900 VHF Omnidirectional Radio.
Other equipment that Rockwell Collins will be providing includes: Communication Management Units, Satellite Communications Systems, VHF and HF transceivers, VHF Omnidirectional Radio, Distance Measuring Equipment, Automatic Direction Finders, Multi Mode Receivers, Mode S Transponders, Cockpit Voice Recorders, Flight Data Recorders, Emergency Locator Transmitters, Flight Deck Printers and the Data Management Units.

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