Key Terms Flashcards
A device used to measure the rate of an aircraft’s rotation about its vertical axis through 360 degrees. A rate gyro is affected by the roll or pitch of the aircraft but aligns itself with the fore and aft line.
Rate Gyro
A type of actuator used on the flight controls of large aircraft.
Power Control Actuator
The compound of an ILS that provides course guidance to the runaway.
localizer
The portion of a radio wave reflected from the ionosphere
sky wave
A wire that runs from the top of the fuselage to the leading edge of the vertical stabilizer, used for radio communication and navigation purposes.
wire antenna
Radar beacon transponder. A radar transmitter-receiver that transmits a coded signal every time it is interrogated by a ground radar facility.
transponder
A type of radio wave that is transmit- ted above 30 MHz.
Space waves travel in a straight line and do not bounce off the ionosphere.
Space waves are used to communicate with satellites in orbit.
space wave-
A type of radar transceiver installed in military aircraft that sends an identifi- cation signal to the primary radar to distinguish a friendly aircraft from an enemy aircraft.
Developed during World War II, this system has been adopted by Air Traffic Control (ATC) to interrogate Mode C and Mode S transponders. Known in military aviation as IFF.
secondary radar-
A contraction of selective calling refer- ring to an automatic signaling system used in air- craft to notify a particular aircraft of an incoming call.
SELCAL-
A type of interference signal introduced by the United States Department of Defense to degrade the accuracy of the GPS signal for national security reasons. It was deactivated May 1, 2000, which resulted in a more accurate GPS signal
selective availability (SA) -
- An electronic device that converts DC into AC. 2. An electronic circuit that produces AC with frequencies determined by the inductance and capacitance in the circuit.
oscillator-
Aircraft equipment that makes use of the reflection of radio waves from the ground to determine the height of the aircraft above the surface.
radar altimeter-
A device that measures the height of an aircraft above the terrain by means of the transmissions of a continuous wave, constant amplitude, frequency modulated signal. The difference in the frequency of the reflected signals at any time is read on the RA indicator in feet above the ground.
radio altimeter (RA) -
A device that, by measuring the time inter- val between transmission and reception of radio pulses and correlating the angular orientation of the radiated antenna beam or beams in azimuth and/or elevation, provides information on range, azimuth, and/or elevation of objects in the path of the trans- mitted pulses.
radar -
A radar system using only a transmitter, receiver, antenna, and cathode-ray tube dis- play to indicate radar traffic. No transponder signal is added. Indication on display is referred to as a primary return.
primary radar -
A degradation in chemical cell performance, particularly in the case of Leclanche cells, caused by gas formation and the resulting insulation of portions of the pole area.
polarization -
An electronic naviga- tion facility transmitting a 75 MHz vertical fan or boneshaped radiation pattern. Marker beacons are identified by their modulation frequency and key- ing code, and when received by compatible airborne equipment, indicate to the pilot, both aurally and visually, that he is passing over the facility.
marker beacon (MB)
A non-directional, quarter- wave antenna utilizing a ground plane that serves as a quarter-wave reflector. Used for transmitting and receiving radio communications in the higher frequency bands.
Marconi antenna
Acronym for Long Range Navigation. A maritime navigation system that relies on trans- missions of low-frequency waves from ground- based transmitter stations. These low-frequency waves can be transmitted thousands of miles out to sea and picked up by a ship’s LORAN receiver. LORAN-C is a system used by pilots to fly aircraft under IFR flight rules, but is now seldom used due to the popularity and accuracy of GPS.
LORAN-C-
A highly directional sensitive antenna wound in the form of a coil used to find the direction between the loop and the station transmit- ting the received signal.
loop antenna
The process of changing an electromagnetic wave’s ability to transmit information by varying its amplitude, phase, or frequency.
modulation -
A navigation aid that uses a computer and motion sensors such as accelerometers and ring laser gyros (RLG) to continually track the position, orientation, and velocity of a moving object without the need for external references. This system requires a crewmember to enter initial location data, after which it computes its own located position using information integrated from the motion sensors.
inertial reference system (IRS) -
Provides vertical guidance for aircraft during approach and landing. The glides- lope/glide path is based on the following:
a. Electronic components emitting signals which provide vertical guidance by reference to airborne instruments during instrument approaches such as ILS/MLS; or
b. Visual ground aids, such as VASI, which pro- vide vertical guidance for a VFR approach or for the visual portion of an instrument approach and landing.
c. PAR, used by ATC to inform an aircraft making a PAR approach of its vertical position (elevation) relative to the descent profile.
ing system.
glideslope (GS) -
A form of transmit- ting information by using radio carrier waves. With FM, the frequency of the carrier changes proportionately with the change in the amplitude of the information signal.
frequency modulation (FM)
A radiated energy wave that has two components-an electrical com- ponent and a magnetic component-that radiate in phase, but perpendicular to one another. EM waves include radio waves, microwaves, infrared waves, visible light, ultra violet radiation, X-rays, and gamma rays.
electromagnetic (EM) wave
An electronic circuit that separates, or filters, the carrier wave of a radio frequency transmission signal and recovers the audio wave information signal. Traditionally used in reference to radio receivers, this term is also used in other systems such as computers, where modem is a con- traction of the terms modulation/demodulation.
demodulator
A form of transmit- ting information by using radio carrier waves. With AM, the strength, or amplitude, of the transmitted signal is varied in relation to the signal being trans- mitted. As the frequency of the signal is increased, the amplitude of the carrier wave is also increased.
amplitude modulation (AM)
A type of half wave dipole antenna whose overall length is equal to one-half the wave- length of the EM wave it sends or receives.
Hertz dipole -
The portion of a radio wave that travels to the receiver along the surface of the Earth.
ground wave —
The high frequency alternating cur- rent that can be modulated to carry intelligence by propagation as a radio wave.
carrier wave -
Static noise in electrical radio equipment caused by the friction between the metal or plastic skin of an aircraft and charged particles in the atmosphere.
Precipitation Static
A small length of braded copper or aluminum wire with no more than three mil- liohms of resistance that is attached to the mounting point of an electronic component and the aircraft structure. When properly attached to the aircraft structure, they equalize the potential of all aircraft electronic components. Also known as bonding straps.
bonding jumper -
A radiating electromagnetic field produced by electrically charged objects. EMI affects the behavior of other charged objects or systems in vicinity of the field.
electromagnetic interference (EMI)
Electrical interference caused by improperly installed equipment. The term refers to an unwanted current in a wire con- ductor connecting two points of differing potential that should be the same
ground loop interference
A wire, attached to a magneto aircraft igni- tion system, that grounds the high voltage output (produced by the magneto) to the spark plugs. In the grounded condition, the engine will not start. The ignition switch interrupts the P lead circuit to ground, which permits the magneto to provide volt- age to the spark plugs.
P lead-
In navigation, the angular error in a measured bearing due to the presence of metal structures and engines in the vicinity of the direc- tion finding antenna.
quadrantal error
