The aircraft gyros, accelerometers, synchros, servos,
and computers continually monitor aircraft heading,
attitude, and horizontal and vertical velocities. Any
change in the aircraft's latitude, longitude, or altitude
involves a change in its speed or direction of motion.
The inertia of extremely sensitive accelerometers
resists these changes. This resistance is measured and
recorded by the synchros, servos, and computers. The
computers continually recalculate the movement of the
aircraft based on the latest changes recorded by the
accelerometers. The computers use these calculations
to provide a constantly updated readout of the aircraft's
geographical position. When used with Doppler radar,
an INS greatly improves overall system accuracy.
Q7-16.
Define the radio communication method
known as “radiotelegraphy.”
Q7-17.
Define the radio communication method
known as “radiotelephony.”
Q7-18.
Airborne long-range communications sets
normally operate in a band of what frequency
range?
Q7-19.
Airborne short-range communications sets
operate in what frequency range?
Q7-20.
What is the primary navigational aid used by
the Navy for carrier-based aircraft?
Q7-21.
The Global Positioning System (GPS) is a
space-based radio position and navigation
system designed to provide what type of
information?
Q7-22.
The GPS Satellite Vehicle consists of how
many operational satellites?
Q7-23.
Doppler radar uses what type of transmission
to measure the ground speed and drift angle
of the aircraft?
RADAR
LEARNING OBJECTIVE: Recognize the
operating principles, types, and uses of radar.
The acronym radar means RAdio Detection And
Ranging. Radar is a radio device used to detect objects
at distances much greater than is visually possible.
Detectable objects include aircraft, ships, land areas,
clouds, and storms. In addition to detecting these
objects, the radar shows their range and relative
position.
Radar was shrouded in secrecy all through World
War II. It was one of our most important offensive and
defensive weapons systems. Today, radar is used in
most types of aircraft, and plays a major role in the
mission of naval aviation. Modern developments have
led to many specialized types of radar; however, the
basic principle upon which it functions is simply echo
waves.
ECHO PRINCIPLES
Radar works on the echo principle, as shown in
figure 7-21. If a person shouts toward a cliff, in a few
seconds the voice returns as an echo. If a radio wave is
sent towards a cliff from a radio transmitter through an
antenna, it would echo and return to be picked up
through the antenna and sent to the radio receiver.
Sound waves travel about 1,100 feet per second,
while radio waves travel at the speed of light (about
7-16
TRANSMITTER-RECEIVER
ANF0721
Figure 7-21.—Reflection of sound and radio waves.
