NAVIGATION

> The art of detecting the movement of a craft from one

point to another along a desired path.

METHODS OF NAVIGATION

>the navigator fixes his position

on a map by observing known

landmarks.

1. NAVIGATION BY PILOTAGE

2. CELESTIAL NAVIGATION >also called as Astronomical

Navigational

>it is accomplished by measuring

the angular position of celestial

bodies.

METHODS OF NAVIGATION

>the positions of crafts at any instant

of time is calculated from previously

determined position, the speed of its

motion with respect to the earth with

the direction and the time elapsed.

>it is the most common and widely

used method of navigation.

3. NAVIGATION BY DEAD

RECKONING (DEDUCED

CALCULATIONS)

4. INERTIAL NAVIGATION >navigation using motion sensors and

computers

METHODS OF NAVIGATION

>uses electromagnetic waves to attain

a fix.5. RADIO NAVIGATION

NAVIGATION PARAMETERS

>latitude and longitude1. POSITION

2. DIRECTION

3. DISTANCE

4. SPEED

5. TIME

>bearing, azimuth, and relative bearing

>nautical mile (6080 ft.), statue mile

(5280 ft.), and radar mile (6000 ft.)

>1 knot (1 nautical mi./hr)

>EST Meridian (GMT-5), CST (GMT-6),

MST Meridian (GMT-7), PST Meridian

(GMT-8)

NAVIGATION PARAMETERS

WORLD TIME ZONES

NAVIGATION PARAMETERS

Greenwich MeanTime

0 degree (Zulu Time)

UTC – Universal Time Coordinate

1. GMT

2. PST

3. MST

4. CST

5. EST

Pacific Standard Time

GMT - 8

Mountain Standard Time

GMT - 7

Central Standard Time

GMT - 6

>Eastern Standard Time

GMT - 5

POINTS OF BEARING

POINTS OF BEARING

Dead Ahead1. 90 degrees

2. 0 degree

3. 180 degrees

4. 270 degrees

On Starboard Beam

On Port Beam

Dead Astern

RELATIVE BEARING

Axes of rotation

Pitch (Elevator)1. Lateral Axis

2. Longitudinal

Axis

3. Vertical Axis

Roll (Aileron)

Yaw (Rudder – control mechanism)

RADAR

>Radio Detection and Ranging

>basically, a means of gathering

information about distant objects

or targets by sending

electromagnetic waves at them

and analyzing the echoes.

TYPES OF RADAR

A. According to the Location of Transmitter and Receiver

1. Monostatic

2. Bistatic

3. Multistatic

transmitter and receiver are both

located at the same point

transmitter and receiver are

separated by quite large distances

TYPES OF RADAR

B. According to the Form of Transmitted Signal

1. Pulsed

2. Continuous Wave

forms in short burst of RF energy

gives the speed without the range

and distance using the principle of

Doppler Effect

TYPES OF RADAR

C. According to the Information Given

1. Primary

2. Secondary

Primary Surveillance Radar

(azimuth, range)

Secondary Surveillance Radar

(altitude, identification)

DOPPLER EFFECT

> the apparent frequency of electromagnetic or sound waves depends on

the relative radial motion of the source and the observer

> if the source and observer are moving away from each other, the

apparent frequency will decrease, while if they are moving toward each

other, the apparent frequency will increase

DOPPLER EFFECT

> postulated by Christian Doppler in 1842

> was given a firm mathematical basis by Armand Fizeau

where: v = velocity of the target in m/sec

λ = wavelength in m

fd = Doppler frequency

θ = angle of direction of target

and the radar line of sight to the target

RADAR range

NOTE: the transmitted signal takes 6.16 µsec to travel one radar mile

Therefore,

Round Trip = 12.36µsec

Pulse repetition time

> determines the maximum distance to the target to be measured

Maximum unambiguous

range

> range beyond which objects appear as second return echoes

Minimum effective range

Duty cycle

> Duty Cycle = Average Power / Peak Power

examples

1. What is the duty cycle of radar with a PW of

3µsec and a PRT of 6msec?

examples

2. Calculate the average power when peak power

is 1kW, PW is 3µsec and rest time of 1997µsec.

Radar range equations

Since

Pmin = kTB(F-1)

Then,

Radar range equations

where: Rmax = maximum range

Pt = transmitting power

Ao = capture area of the transmitting antenna

S = radar cross sectional area

Pmin = minimum receivable power

λ = wavelength

examples

1. Calculate the minimum receivable signal in a

radar receiver which has an IF BW of 1.5 MHz

and a 9dB noise figure.

examples

2. Calculate the maximum range of a radar

system which operates at 3cm with a peak pulse

power of 500kW, if its minimum receivable power

is 10-13 watts, the capture area of its antenna is 5

sq. m. and the radar cross sectional area of the

target is 20 sq. m.

TARGET PROPERTIES

> the radar cross section or effective area of the target

depends on the frequency used

RAYLEIGH REGION

> the target is small compared to a wavelength, its cross

sectional area for radar appears much smaller than its

real cross section

RESONANCE REGION

> when the circumference of a spherical target is between

1 and 10 wavelengths, the radar cross section oscillates

about the real one

OPTICAL REGION

> for shorter wavelengths, the radar and true cross

sections are equal

TARGET CROSS SECTION

The Radar Cross Section of the Target Depends on:

1. polarization of the incident wave

2. degree of surface roughness

3. use of special coatings on the target

4. aspect of the target

PULSE CHARACTERISTICS

> flat topped rectangular pulse

> leading must be vertical to ensure that the leading

edge of the received pulse is also close to vertical for the

exact measurement of the target range.

> steep trailing is needed for the transmitted pulse

so that the duplexer can switch the receiver over the

antenna as soon as the body of the pulse has passed

RADAR ANTENNAS

> use dipole or horn fed paraboloid reflectors or at least

reflectors which is basically paraboloid shape

SCANNING PATTERNS

1. Horizontal

2. Nodding

SCANNING PATTERNS

3. Helical

4. Spiral

ANTENNA TRACKING

> sequential lobe

> the direction of the antenna

beam is rapidly switched between

2 positions

1. Lobe Switching

Technique

2. Conical scanning

3. Monopulse tracking

> logical extension of lobe

switching

> a system using 4 horn antennas

displaced about the central focus

of the reflector

Radar display methods

1. A Scope

> deflection modulation of the CRT screen

Radar display methods

1. A Scope

A-scan > range and intensity presentation

B-scan > range and azimuth presentation

C-scan > elevation and azimuth presentation

Radar display methods

2. Plan Position Indicator

> intensity modulation of a CRT

> shows range, azimuth and speed

> shows a map of the target area

> the brightness at any point on the

screen indicates the presence of an

object there, with its position

corresponding to its actual physical

position and its range being

measured radially out from the

center

Radar display methods

3. Automatic Target Detection

> direct feeding to a computer

Radar display methods

3. Automatic Target Detection

> direct feeding to a computer

RADAR GENERAL TASKS

1. search for targets

2. track them once they have been acquired

TRACKING RADAR SYSTEMS

1. Tracking in angle

2. Tracking in range

a system that gives the angular

position of a target accurately

range information is

continuously obtained

Radar beacons

> small radar sets consisting of a receiver, a separate

transmitter and an antenna which is often

omnidirectional

> when radar transmits a coded set of pulses at the

beacon, the beacon responds by sending back its

specific pulse code, thereby earning its name

transponder

Radar beacons apps

> IFF (Identification Friend or

Foe)

> Calculation of position, similar

to lighthouses

Beacon range equations

Interrogation

Beacon range equations

Reply

example

Calculate the maximum active tracking range of a

deep space radar operating at 2.5 GHz using a peak

pulse power of 0.5 MW, with an antenna diameter of

64m, a noise figure of 1.1 and a 5 kHz BW, if the

beacon antenna diameter is 1m, its noise figure is

13dB and it transmits a peak pulse power of 50 W.

Air traffic control radar

> Aerodrome control

> Approach control

> Area control

PAR: precision approach radar

R<10 n.mi.

ASR: airport surveillance radar

R: 10-60 n.mi

ARSR: air route surveillance

radar

-R: 60-200 n.mi.

DIRECTION FINDERS

Radio Direction Finders are

devices capable of determining the

direction of approaching radio

waves.

RDF – manual (uses loop

antennas)

ADF – automatic

employs 2 loop antennas in 90

degrees (uses goniometer to

terminate loop antennas with coil)

AUTOMATIC DIRECTION FINDER

(ADF)

> automatic determination of relative bearing to a transmitting radio

station or non-directional beacon. Used for weather information and

other broadcast programs. It uses AM with frequency band of 190-

1860 kHz. It employs 2 loop antennas in 900 (goniometer).

DISTRESS FREQUENCIES

> Radio Telephony

> Radio Telegraphy

2182 kHz (A3E / J3E)

156.8 MHz (F3E)

500 kHz

Instrument landing system

(ILS)

> uses localizer, glide, and marker

beacon transmitter to provide a

sloping glide path for instrument

(blind) landing approach of an

aircraft

> highly accurate and dependable

means of navigating to the runway.

When using the ILS, the pilot

determines aircraft position primarily

by reference to instruments

Instrument landing system

(ILS)

1. Localizer > provides lateral

guidance

> a VHF radio

transmitter and

antenna system using

the same general

range as VOR (VHF

Omnidirectional

Range), transmitters

between 108.10 to

111.95 MHz

Instrument landing system

(ILS)

2. Glide slope equipment > provides vertical

guidance

Instrument landing system

(ILS)

3. ILS marker beacons

Marker

Beacon

Code Light Distance to

Threshold

Modulated

Frequency

Outer Blue 4 to 7 nm 400 Hz

Middle Amber 3500 ft 1300 Hz

Inner White 1000 ft 3000 Hz

Instrument landing system

(ILS)

4. Runway lights

> approach lights (white)

provide guidance to the

pilot on an approaching

aircraft to the runway

Instrument landing system

(ILS)

4. Runway lightsSequence lights

a part of an approach light. It

flashes twice in second in

sequence. It distinguishes

aeronautical ground lights in

an aero dome to the other

lights in the area

Instrument landing system

(ILS)

4. Runway lights>runway edge

lights (amber)

provide sufficient

guidance to the pilot

during landing and take

off especially at night or

zero visibility

Instrument landing system

(ILS)

4. Runway lights

>threshold lights

(green)provides information on

the extremely runway

where landing aircraft is

intended to land

Instrument landing system

(ILS)

4. Runway lights

>runway end lights

(red)signifies the end of

runway and is placed on

lines at right angle to

the runway access

Instrument landing system

(ILS)

4. Runway lights

>PAPI lights

(precision approach

path indicator)

provides a positive indicating on the aircraft

position relative to the optimal slope during

final approach to the runway

GROUND-CONTROLLED

APPROACH (GCA)

> an airplane is talked down to a blind landing by means

of ground-based search and precision radars

GROUND-CONTROLLED

APPROACH (GCA)

> an airplane is talked down to a blind landing by means

of ground-based search and precision radars

consisting of extremely high precision microwave radar

equipment that gives the position of an aircraft in range,

azimuth, and elevation.

It is primary designed to bring the pilot through low

overcast of low horizontal visibility so that he can make a

normal landing by visual contact

GROUND-CONTROLLED

APPROACH (GCA)

basically the ground equipment at the airport consists of two

microwave radar sets, which are usually installed in a single trainer

placed adjacent to the runway.

One of the radars, known as the search system, locates all aircraft

within 30 miles or so of the airport and thus provides a radar map of

the vicinity.

It is the initial phase of the GCA and is accomplished with medium

range radar called plan position indicator

> the other radar, called the precision system, provides continuous

information regarding the position of the incoming aircraft with respect

to the runway. The plane may thus be safely talked down along the

sloping glide path

GROUND-CONTROLLED

APPROACH (GCA)

on the final approach leg, the controller, using precision scopes,

takes control.

He also broadcasts verbal instructions, principally concerning

attitude and lateral deviation from the desired glide path, and guides

the pilot virtually to the end of the runway

> on the final approach, the GCA operator uses precision approach

radar (PAR), a short-range precision radar that indicates the proper

glide path for descent

NONDIRECTIONAL BEACONS

(NDB)

are low-frequency transmitters operating into an omnidirectional

vertically polarized antenna.

Usually placed at the ILS outer and middle marker beacon sites

where it is known as compass locator

NONDIRECTIONAL BEACONS

(NDB)

are beacons sending its signal equally well in all directions. It is a

low-frequency beacon with a frequency range of 200 kHz to 415 kHz.

The reception range of the radio beacon is at least 15 nautical miles

and it transmits 2 to 3 letters of identification signal from the Morse

code 8 times per minute.

NDB provides a radio station for use by aircraft. The equipment in

the aircraft consists of an ADF.

NONDIRECTIONAL BEACONS

BEARINGS

Magnetic Bearing = Magnetic Heading + Relative Bearing

Example:

An aircraft has a magnetic heading of 150 degrees and a relative

bearing to an NDB station of 75 degrees. Determine the magnetic

bearing of the station in degrees.

DISTANCE MEASURING

EQUIPMENT (DME)

> an equipment that provides information of the distance between an

aircraft and the VOR station

> together with VOR, they provide the information necessary for

reroute navigation

DISTANCE MEASURING

EQUIPMENT (DME)

1. Transceiver

> sends out signals to

the ground station

DISTANCE MEASURING

EQUIPMENT (DME)

2. Internal computer

> built within the

transceiver that measures

the time interval that

elapsed until the

response

DISTANCE MEASURING

EQUIPMENT (DME)

3. Antenna

> used for both

transmission and

reception

DISTANCE MEASURING

EQUIPMENT (DME)

3. DME controls

> incorporate digital

readouts of frequency,

DME and ground speed

information

DISTANCE MEASURING

EQUIPMENT (DME)

DME displays information

a. distance to the station

b. aircraft’s ground speed

c. time to station

expressed in

nautical miles

expressed in knots

expressed in minutes

VHF OMNIDIRECTIONAL RANGE

(VOR)

a radio facility providing bearing information to

and from such facility at all azimuth within its

service area.

It provides an unlimited number of visual course

legs through the phase comparison of a cardioids-

shaped rotating radiation pattern with a fixed 30

Hz reference signal

VHF OMNIDIRECTIONAL RANGE

(VOR)

VHF OMNIDIRECTIONAL RANGE

(VOR)

1. VOR receiver

> the VOR signals are received

on the antenna normally located

on the vertical stabilizer or on

the top of the fuselage. The

VOR receiver converts signals

from the antenna to the

readings displayed on the

navigation indicator

VHF OMNIDIRECTIONAL RANGE

(VOR)

2. Navigation indicator

> indicator gives the pilot aircraft

position information by means

of three components:

VHF OMNIDIRECTIONAL RANGE

(VOR)

2. Navigation indicator

> indicator gives the pilot aircraft

position information by means

of three components:

a. Track / Omnibearing

selector

used to rotate the

azimuth ring which

displays the VOR track

VHF OMNIDIRECTIONAL RANGE

(VOR)

2. Navigation indicator

> indicator gives the pilot aircraft

position information by means

of three components:

b. To – from / off flag indicates whether the

track will take the pilot

to or from the station

VHF OMNIDIRECTIONAL RANGE

(VOR)

2. Navigation indicator

> indicator gives the pilot aircraft

position information by means

of three components:

c. track deviation bar

(TB)

shows the pilot the position

relative to the track selected

and indicates whether the

radial is to the right or left

when the aircraft heading

agrees generally with the

track selector

VHF OMNIDIRECTIONAL RANGE

(VOR)

3. Track arrow

> a needle that you could think

of as a line that runs through the

station and points in the

direction of the selected track

that divides the area around the

VOR station into halves

VHF OMNIDIRECTIONAL RANGE

(VOR)

4. Reference line

> a line perpendicular to the

track arrow and intersecting it at

the station. It also divides the

VOR reception area to

additional sectors

TACTICAL AIR NAVIGATION

(TACAN)

> a microwave pulse system that provides highly accurate

bearing and range information from a shipboard or ground

radio beacon

TACTICAL AIR NAVIGATION

(TACAN)

> provides an aircraft with continuous distance (range)

and bearing (azimuth) information from a ground beacon

station located within a line-of-sight range up to 195

nautical miles

> operates completely in the UHF band from 962-1213 MHz

TACTICAL AIR NAVIGATION

(TACAN)

> has a total of 126 channels in the UHF band, each being

capable of providing full service for over 100 aircrafts

> provides compass direction with less than one degree

error and is capable of indicating true distance from the

ground station within about 600 feet

> can use a very small ground station antenna which

permits its installation on Air Force Mobile units and Navy

carriers

TACTICAL AIR NAVIGATION

(TACAN)

1. Airborne interrogator – responsor

> the airborne set is a radio set that could be tuned to 126

channels and has a special range and azimuth circuit. It is

generally provided with two indicators, one for showing the

range in nautical miles, the other for indicating the bearing

(azimuth) of the aircraft on the station

TACTICAL AIR NAVIGATION

(TACAN)

2. Ground or shipboard surface beacon

> a beacon that could be triggered by distance

interrogation pulses coming from an airborne radio set.

When triggered, it will respond by sending out

synchronized reply pulses and also identifies itself aurally

in International Morse Code characters

VORTAC

> a facility consisting of two components or is referred to

as a combination of a VOR and a TACAN therefore

deriving the name VORTAC

VORTAC

> this system is an ICAO (International Civil Aviation

Organization) Rho-Theta system implemented by co-

locating VOR and TACAN azimuth and TACAN distance

measuring capability at one sight

LOW FREQUENCY RANGE (LFR)

> range stations that provide four aircraft course legs (the

overlapping of two figure-of-8 patterns)

LOW FREQUENCY RANGE (LFR)

the low frequency radio range depends on the superposition of two

figure-of-eight directional antenna patterns at right angle with each

other.

These patterns provide on-course signals which interlock with those

of surrounding station to form easily followed airways.

When two vertical antenna towers are properly fed with radio

frequency energy they produce two figure-of-eight radiation patterns.

This makes production of on-course signals simpler and easier.

Radio range stations operate on frequency between 200 kHz and 400

kHz

LOW FREQUENCY RANGE (LFR)

> four sectors are created by these towers between which are four

regions that overlap each other. In these regions, both signals from

towers are present. Signal in this overlapping zones are heard as

continuous tones blend rather than be heard individually. As long as an

aircraft flies over this zone where on-course signals are present, pilots

would hear continuous signals

LOW FREQUENCY RANGE (LFR)

if two pairs of vertical tower are placed in a square patterns at right

angles to each other, the fifth center tower is used for transmitting

weather reports.

With two figure-of-eight patterns available the production of on-

course signals becomes a simple matter.

The code signal A is transmitted over one pair of diagonally opposite

towers, and the code signal N is transmitted over the pair of towers.

In this way, four signal zones, called sectors, are produced, two of

which carry the A signal while other two carry the N signal. Between

the four sectors there are regions of overlapping

LOW FREQUENCY RANGE (LFR)

Cone of Silence

> directly above a radio range station there exists an area where

practically no signal is heard. This area has the shape of inverted cone

and is known as the cone of silence. A pilot passing through the cone of

silence would know that he was directly over the range station whose

signal he had been receiving.

HYPERBOLIC NAVIGATION

SYSTEM

> produces hyperbolic lines of position through the measurement of

the difference in times of transmission of radio signals from two or

more synchronized transmitters at fixed points

HYPERBOLIC NAVIGATION

SYSTEM

> when synchronized signals are received from two transmitting

stations, the difference in the times of arrival is constant on a

hyperbola having the two transmitting stations as foci

the measured time difference locates the receiver on the hyperbolic

line of position for that time difference.

Another pair of transmitters provides another hyperbolic line of

position.

The intersection of the lines of position provides a navigational fix.

HYPERBOLIC NAVIGATION

SYSTEM

LORAN

> an electronic method of determining ship position by the

reception of signals from transmitting stations of known

locations

LORAN

radio signals consisting of short pulses are continually transmitted

from a pair of shore-based stations.

These signals are received aboard the ship by means of a specially

designed receiver.

The difference in time of arrival of the two signals is measured by

means of an indicator associated with the receiver.

The measured time difference is used together with special tables or

charts to determine line of position on the surface on the earth’s

surface.

Two lines of position obtained from two pairs of transmitting stations

intersects at a given LORAN fix.

LORAN A

> the ground waves of a LORAN A transmitter with a peak

power of 100 kW can be received over sea at a distance of

500 to 700 n.mi. and a distance of up to 1100 n.mi. with

ground and sky waves. Over land these distances are

considerably shorter.

LORAN C

> LORAN C transmitters operate at lower frequencies of

100 kHz. At this frequency, ground waves of a 300 kW

transmitter can be received up to 1200 n.mi.

LORAN D

the advantage of LORAN D over LORAN A is that ground stations

are transportable and can therefore be quickly deployed.

This mobility is gained at the expense of the substantially reduced

radiated power (30 kW peak) inherent in the somewhat smaller

transmitter and lower antenna towers (400 ft. or 120 m) to partially

compensate for this reduction in radiated power.

LORAN D is configured to use 16 phase-coded pulses 500µsec part

in each group.

LORAN D phase code is different but compatible with LORAN C

system format and 100µsec apart as in LORAN C. pulse sampling is

carried out near the signal peak because sky-wave delays are greater

at short range.

DECCA

> a continuous wave hyperbolic system operating in the 70

to 130 kHz band

> a hyperbolic navigation system which establishes a line

of position from measurement of the phase difference

between two continuous-wave signals

OMEGA

a navigation system developed by US Navy in 1957.

It is a hyperbolic system which works in the VLF region

and has a very long base line of the order of 7000 km

> a global radio navigation system that provides position

information by measuring the phase difference between

signals radiated by a network of transmitting stations

SONAR

> a system used

abroad navy ships

for sonic and ultra

sonic underwater

detection, ranging,

sounding and

communications

> sound navigation and ranging

TCAS

> Traffic alert and Collision Avoidance System

TCAS

> traffic alert and collision avoidance system

> TCAS tracks these other airplanes or intruders, if

equipped with an ATCRBS (air traffic control radar beacon

system)

TCAS

Two types of collision avoidance alerts

1. traffic advisory (TA)

2. resolution advisory

(RA)

shows the relative

position of any intruder

airplanes

vertical maneuver to

avoid a possible

airplane collision

GPS

> Global Positioning System

> a space-based satellite navigation system that provides location and time information in all weather conditions, anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites

GPS

> NAVSTAR GPS

> the Navigation Satellite

Timing and Ranging Global

Positioning System

(NAVSTAR GPS) is a

worldwide navigation radio

aid which uses satellite

signals to provide accurate

navigation information

GPS

> GLONASS GPS

> Globalnaya navigatsionnayasputnikovaya sistema or Global Navigation Satellite System, is a space-based satellite navigationsystem operated by the Russian Aerospace Defence Forces.

GPS

> provides specially coded satellite signals that can be

processed in a GPS receiver, enabling the receiver to

compute position, velocity and time

> four GPS satellite signals are used to compute positions

in three dimensions and the time offset in the receiver

clock

> navigation in three dimensions is the primary function of

GPS

GPS

1. Space segment

> composed of a constellation of 24 satellites arranged in

six separate orbital planes of four satellites each on a

circular orbit and have the following characteristics:

a. 550 inclination to the equator

b. an altitude of approximately 20,200 km with an orbital

period of 12 sidereal hours

c. 11 hrs, 58 min orbital period

GPS

Satellites give:

a. satellite position

b. constellation data

c. atmospheric corrections

GPS

2. Control segment

Monitor stations locations

> Kwajalein

> Hawaii

> Ascension Island

> Diego Garcia

> Colorado Springs (master control station)

GPS

3. User segment

Main advantages

-anytime, anywhere, and in any weather

-highly accurate measurements

-GPS has almost endless applications

Q & a

An area directly above a radio range station where

practically no signal is heard.

a) radio range

b) cone of silence

c) coverage area

d) RDF area

Q & a

A shipboard equipment which measures the distance

between the ship’s bottom and the ocean floor by sending

the ultrasonic pulses via a transducer which are reflected

at the sea bottom and received with the same transducer.

a) echosounder

b) SONAR

c) compandor

d) hydrophone

Q & a

The ratio of the pulse width to the time

between the beginning of 2 pulses.

a) duty cycle

b) Doppler shift

c) blind speed

d) tracking error

Q & a

A navigation system from which hyperbolic lines of position

are determined by measuring the difference in the times of

arrival of pulses from widely spaced, synchronized

transmitting stations.

a) LORAN

b) TACAN

c) DME

d) VOR

Q & a

A measure of the ability of the receiver to

detect transmission.

a) selectivity

b) sensitivity

c) detector

d) demodulator

Q & a

Radio range stations in LFR operate on

frequencies between

a) 20 kHz & 40 kHz

b) 200 kHz & 400 kHz

c) 30 kHz & 300 kHz

d) 2 MHz & 4 MHz

Q & a

The fifth center tower in an LFR is used for

transmitting _____ reports

a) hazard

b) range

c) weather

d) direction

Q & a

The direction of one terrestrial point from another,

expressed as angular distance from a reference

direction.

a) heading

b) bearing

c) relative bearing

d) true bearing

Q & a

DME operates in the ________ frequency

band.

a) LF

b) HF

c) VHF

d) UHF

Q & a

SONAR equipment feature which enlarges

all echoes on the screen.

a) grayline

b) zoom

c) sensitivity

d) ASP

Q & a

A major obstacle in achieving high speed

operation in a SONAR manifested by turbulent

water flow.

a) transom

b) cavitation

c) thru-hull

d) shoot thru

Q & a

Considered to be the SONAR unit’s antenna

a) crystal

b) transducer

c) localizer

d) transceiver

Q & a

The speed of sound through water

a) 4800 m/sec

b) 1463 m/sec

c) 4800 miles/sec

d) 5000 ft/sec

Q & a

What is an electronic measuring equipment used

in navigation operating in 1 GHz band which

provides bearing and distance indication?

a) TACAN

b) VOR

c) ILS

d) DME

Q & a

An instrument used to measure one location

in terms of coordinates.

a) global positioning system

b) hydrometer

c) altimeter

d) increductometer

Q & a

The distance in angular degrees in a

clockwise direction from magnetic north.

a) phase difference

b) azimuth

c) latitude

d) longitude

Q & a

_______ is used with a localizer station to indicate

the desired approach path of an aircraft.

a) glide slope system

b) marker

c) LORAN chart

d) OBI

Q & a

_______ is a 30 Hz signal which has a constant

phase at all points around the VOR station.

a) reference signal

b) variable signal

c) ID signal

d) voice modulation

Q & a

If the peak transmitted power in a radar system is

increased by a factor of 16, the maximum range

will be increased by a factor of

a) 2

b) 4

c) 8

d) 16

Q & a

After a target has been acquired, the best

scanning system for tracking is

a) nodding

b) spiral

c) conical

d) helical

Q & a

The coho in MTI radar operates at the

a) intermediate frequency

b) transmitted frequency

c) received frequency

d) pulse repetition frequency

Q & a

If the target cross section is changing , the

best system for accurate tracking is

a) lobe switching

b) sequential lobing

c) conical scanning

d) monopulse

Q & a

The number of pulses that occur per second

in a radar is called

a) PRR

b) pulse train

c) pulse width

d) duty cycle

Q & a

The phenomenon evidenced by the change in the observed frequency

of a sound or a radio wave caused by the time rate of change in the

magnitude of the radial component of relative velocity between the

source and the point of observation.

a) tunnel effect

b) Doppler effect

c) Gunn effect

d) end effect

Q & a

_______ are non-directional transmitters that

operate in the LF and MF bands.

a) radio beacons

b) DME

c) ILS

d) LORAN

Q & a

When a single antenna is intended to be used for

transmitting and receiving , it is necessary to use

a

a) duplexer

b) diplexer

c) combiner

d) translator

Q & a

The most commonly used component in a RADAR

transmitter is the _______ tube.

a) dynatron

b) twystron

c) magnetron

d) cyclotron

Q & a

A radar display that sweeps outward of the center

of the screen while rotating is known as

a) CRT

b) PPI

c) D-scope

d) periscope

Q & a

The time from the transmission of a radar pulse to

its reception is 0.12 msec. The distance to the

target is _________ nautical miles.

a) 4.85

b) 11.2

c) 9.7

d) 7.9

Q & a

The pulse duration of a radar signal is 600

nanoseconds. The PRF is 185 pulses per second.

The duty cycle is

a) 0.01%

b) 5.5%

c) 31%

d) 97%

Q & a

Doppler effect allows which characteristic of a

RADAR target to be measured?

a) distance

b) speed

c) size of target

d) azimuth

Q & a

Most radar antennas use

a) dipoles

b) broadside array

c) horn and parabolic antenna

d) discone

Q & a

The following are the components of an ILS

except:

a) localizer

b) glide slope

c) markers

d) goniometer

Q & a

The following are hyperbolic systems

except:

a) LORAN

b) DECCA

c) OMEGA

d) TACAN

Q & a

What do you call an electronic measuring equipment used

in navigation which provides runway direction, distance

and height guidance to permit blind landing?

a) DME

b) VOR

c) TACAN

d) ILS

Q & a

A radio aid to navigation that uses a rotatable loop

or other highly directional antenna arrangement to

determine the direction of a radio signal.

a) DME

b) RDF

c) TACAN

d) VOR

Q & a

An agency of the United Nations, that formulates

standards and recommended practices for all civil

aviation.

a) ICAO

b) CAA

c) IATA

d) ATO

Q & a

LORAN is a navigation system used

primarily for

a) obtaining fixes over large distances

b) approach control

c) blind landing

d) IFF surveillance operation

Q & a

TACAN is a navigational aid providing

a) speed and height indication

b) bearing and weather information

c) bearing and distance indication

d) cone of confusion

Q & a

Otherwise known as Coastline refraction or

the refraction of waves towards the

coastline.

a) Polarization effect

b) Land effect

c) Skin effect

d) Luxembourg effect

Q & a

Low-power radar uses

a) RIMPATT

b) TRAPATT

c) magnetron

d) IMPATT

Q & a

RADAR means:

a) Radio Detection and Rating

b) Radio Detection and Ranging

c) Radio Distance and Ranging

d) Radio Delay and Ranging

Q & a

A long range navigation system in which two pairs of

ground stations transmit pulsed signal, which are used by

aircraft or ships to determine their position.

a) LORAN

b) SHORAN

c) GEE

d) TCAS

Q & a

LORAN stands for

a) low radar navigation

b) low range navigation

c) long range radar navigation

d) long range navigation

Q & a

LORAN was developed in the United States during WWII.

What system equivalent to LORAN, which was developed

in England and is used for guiding high-flying bombers

over Germany during WWII?

a) SHORAN

b) DECCA

c) OMEGA

d) GEE

Q & a

What navigational system that uses the principle

known as hyperbolic navigation?

a) GEE

b) LORAN

c) OMEGA

d) All of the above

Q & a

Navigation principle that depends on the measurement of

the difference in distance to two fixed stations whose

separation distance is accurately known.

a) triangulation

b) hyperbolic

c) elliptic

d) pilotage

Q & a

In hyperbolic navigation, how many sets of

hyperbolas are needed before a position (fix) is

obtained?

a) 2

b) 4

c) 6

d) 8

Q & a

In LORAN system, at least how many ground

stations are needed before a position (fix) is

obtained?

a) 2

b) 4

c) 6

d) 8

Q & a

In GEE system, at least how many ground

stations are needed before a position or fix is

determined?

a) 2

b) 3

c) 5

d) 7