Aviation Communication and Navigation Systems

The high frequency band (2 to 25 megahertz).

Amplitude modulation (AM) and frequency modulation (FM).

It is a piece of radio communications equipment in which all of the circuits for the receiver and the transmitter are contained in one housing.

No, this requires a license issued by the Federal Communications Commission.

A UHF stub antenna.

On the center line of the belly of the aircraft as far from any other antenna as is practical.

Dipole antenna, Marconi antenna, and loop antenna.

Marconi antennas.

Static wicks aid in the dissipation of static that builds up on the aircraft. Built-up static can cause radio receiver interference caused by corona discharge emitted from the aircraft as a result of precipitation static.

To aid in communication between the flight crew, or between the flight crew and the cabin crew.

Coaxial cable.

A type of two-conductor electrical cable in which the center conductor is encased in insulation inside a braided shield that serves as the outer conductor. Coaxial cables are normally used for attaching radio receivers and transmitters to antennas.

Refer to the radio installation instructions for the correct part number for the cable and connectors.

The routing should be as direct as possible, there should be no sharp bends in the coax, and it should be kept away from heat that could soften the insulation.

A coaxial cable connector that is connected by inserting the guide pins on the male connector into slots in the female connector and twisting the connector one quarter turn.

A vertically polarized whip antenna.

In the VHF band between 30 and 300 megahertzs

ACARS is a two-way communication link between an airliner in flight and the airline's main ground facilities. Data is collected in the aircraft by digital sensors and is transmitted to the ground facilities. Replies from the ground may be printed out so the appropriate flight crewmember can have a hard copy of the response.

121.5 and 243.0 megahertz.

In the tail of the aircraft or as far aft as possible, so it will be least likely to be damaged in a crash.

When the transmitter has been in use for more than 1 cumulative hour, when the battery expiration date has been reached, or when 50% of their useful life or charge has expired.

By the date marked on the outside of the transmitter.

Every 12 calendar months.

An inertia switch that detects an impact parallel to the longitudinal axis of the aircraft as would occur in a crash.

Actuate the test switch and listen on 121.5 or 243.0 MHz. Make the test during the first five minutes of the hour and do not allow the ELT to operate for more than 3 sweeps. If the ELT is operated outside of this time frame, you should contact the control tower before conducting the test.

A directional loop antenna and a nondirectional sense antenna.

The doubler reinforces the skin so wind loads on the antenna will not cause the skin to flex and crack.

On top of the aircraft, along the center line of the fuselage.

The ILS localizer.

In the VHF band, between 108.0 and 117.95 megahertz.

Along the center line of the belly of the aircraft, as far from any other antenna as is practical.

In the UHF band, between 962 and 1,024 megahertz, and between 1,151 and 1,213 megahertz.

Direct distance to the station that the signal is received from.

A localizer signal provides horizontal guidance to the centerline of the runway. A separate glideslope provides vertical guidance of the aircraft down the proper slope to the touchdown point on the runway.

From satellites that orbit around the Earth.

Between five and eight satellites.

The amount of time it takes for signals to reach the aircraft GPS receiver from transmitting satellites is combined with each satellite's exact location to calculate the position of an aircraft.

The aircraft transponder.

This is an aural command to the pilot to take a specific evasive action (i.e., DESCEND). The computer is programmed such that the pilot in the encroaching aircraft receives an RA for evasive action in the opposite direction (if it is TCAS Il equipped).

Onboard weather radar signals bounce off of precipitation only. Clouds do not create a return.

information that comes from an outside source. Onboard weather radar, lightning detectors, and satellite or other source weather radar

The landing decision height when on an instrument approach.

From a radio altimeter.

It frees the human pilot from continuously having to fly the aircraft, and flies with a high degree of precision. It also couples with various electronic navigational aids.

Command, error-sensing, correction, and follow-up.

Gyros.

Hydraulic, pneumatic, and electric.

It stops the control movement when the surface has deflected the proper amount for the signal sent by the error sensor.

The two parameters are speed mode and thrust mode. In speed mode, the throttle is positioned to maintain a set target speed. In thrust mode, the engines are maintained at a fixed power setting to meet the different phases of flight (takeoff, climb, descent, etc.).

A force trim system holds the cyclic control in the position at which it was released. A more advanced system uses electric actuators that make inputs to the hydraulic servos based on control commands from a computer that senses helicopter attitude.

Below 2,500 feet.

Aircraft GPS location, altitude, velocity, and speed.

Ground-based stations and other aircraft.

Weather text and graphics information, ATIS information, and NOTAMs.

A transponder provides positive identification and location of an aircraft on the radar screens of ATC.

For aircraft equipped with an altitude encoder, the transponder also provides the pressure altitude of the aircraft to be displayed adjacent to the AT on-screen blip that represents the aircraft.

A signal from an ELT can trigger a search and rescue operation, or at the very least, an inquiry to find out where the signal is coming from. Testing inside a metal hangar does not prevent the ELT's signal from being picked up by Cospas-Sarsat satellite system.

Physical harm is possible from the high energy radiation that is emitted.

Wire harnesses need to be protected from chafing and from interfering with other systems, especially those that have movement (retractable landing gear, flight controls, etc.). The routing of wire bundles also needs to consider the environmental condition that will be encountered (heat, corrosive environments, moisture, etc.). Wire bundles also generate magnetic fields and should not be routed close to other equipment that is sensitive to magnetic interference.

Antennas must be able to withstand high air loads and require a mounting doubler to be installed on the aircraft skin. The location of the antenna must not interfere with other locations and must be mounted in an area where signals can be optimally transmitted and received. Antennas must be electrically matched to the receiver and transmitter that

It is important that static wicks discharge static at points a critical distance away from avionics antennas where there is little or no coupling of the static to cause interference or noise on the radio.

The risks of working on live electrical circuits include inadvertent shorting of a positive voltage to ground, which could cause damage to a component, or inadvertent activation of systems. Additionally, power systems can cause electrical shock and injury to personnel.