The document outlines various navigation aids and systems. It discusses ground-based radio navigation systems, satellite navigation systems like GPS, and aircraft landing systems. It also defines key navigation terms and concepts. Navigation is defined as guiding movement from one location to another. Common navigation methods include piloting, dead reckoning, celestial navigation, inertial navigation, and electronic/radio navigation.

1. Navigation Aids
By Dr Paul Fahamuel Mmbaga

2. Course Outline
Introduction
•Navigation terms
•Definition of Navigation

3. Course Outline
Radio Navigation Systems
•Ground – Based Navigation Systems
•Radio Navigation Stations
•Satellite Navigation Systems
•Direction Finders

4. Course Outline
Introduction to Radio Astronomy
•Definition of Radio Astronomy
•Atmospheric Windows
•Radio Telescopes
•Radio Interferometry
•Astronomical sources

5. Course Outline
Aircraft – Landing Systems
•Instrument Landing System (ILS)
•Ground – Controlled Approach (GCA)
System
•Microwave Landing System

6. Course Outline
Underwater Navigation
•The Echo sounder
•The Doppler Log
•Underwater Navigation Aids Transducers

7. Navigation terms
Angle of cut: Where lines from two aircraft cut
Approach path: Path between where aircraft
starts descending and point of touch down

8. Navigation terms
• Azimuth: Angle of horizontal plane with respect to the true North

9. Navigation terms
• Back course: Area behind localizer
• Coherent pulses: Whose phase of rf cycles within a pulse is retained
for measurement purposes.(show the phase difference between the
transmitted and received pulse)

10. Navigation terms
• Cone of Ambiguity: In very high frequency omnidirectional radio-
range (VOR) and Tactical air Navigation (TACAN),cone of ambiguity is a
conical volume of air space above beacon in which bearing
information is unreliable.

11. Navigation terms
• Cone of Silence: Conical volume above antenna where field strength
is low
• Crab angle: Correction angle to compensate for wind drift. Angular
difference between course and heading

12. Navigation terms
• Decision gate: The point at which a pilot should decide to land even if
there is a misapproach.
• Pitch: Angular displacement between longitudinal axis of aircraft and
the horizontal
• Roll: Angular displacement between transverse axis of vehicle and the
horizontal

13. Navigation terms
• Runway Visual Range (RVR): Forward distance along runway during
landing approach

14. Navigation terms
• Yaw:
The angle between a line in the direction of flight and a plane through
the longitudinal and vertical axes of an aircraft

15. What is navigation?, Survey?
• Navigation can be defined as the means by which a craft is
given guidance to travel from one known location to another.
Survey can be defined as to examine and record the features
• Alternatively, navigation is a process or technique used for
directing the movement of a vehicle (aeroplane, ship, missile
etc) from one position to another along the desired
trajectory.
• When we navigate, it is necessary to determine where we
are, how to go from where we are to where we want to be.

16. Navigation methods
Five practical methods of navigation:
• Piloting: This consists of fixing a craft’s position with respect to
familiar landmarks.
• It is the simplest and most ancient method of navigation.
• Dead Reckoning: Method of determining position of a craft by
extrapolating a series of measured velocity increments
• Originally this was called “ded reckoning” for “deduced reckoning”, but
newspaper reporters called it “dead reckoning” and made the name popular

17. Navigation methods
• Celestial Navigation: Method of computing position from precisely
timed sightings of the celestial bodies, including the stars and the
planets
• Inertial navigation: Method of determining a craft’s position by using
computer, motions sensors (accelerometers) and rotation sensors
(gyroscopes) to continuously updating the position based on the
previous location and velocity.

18. Navigation methods
• Electronic or Radio navigation:
Method of determining a craft’s position by
measuring the travel time of an electromagnetic
wave as it moves from transmitter to receiver

19. Generalized navigation system (Block
diagram)
Electronic
Navigational
Aids
Pilot’s
Commands
(in case the
vehicle is
manned one)
Motion
Sensor
Pilot’s
Displays
Control
System
Processor
(GN & C)

20. Radio Navigation System
Radio navigation can be broken into two major
classifications:
• Active radio navigation system
• Passive radio navigation system

21. Satellite Navigation Systems
Transit System
• Specialized receivers tuned to the transmissions of polar orbiting
satellite of the Navigational Satellite System can provide very accurate
navigational position.
• Although the system was originally intended for military purposes it is
available for civil applications by both water and land – based mobile vehicles

22. Satellite Navigation Systems
Transit System ……..
•The space link part of this system consists
typically of five satellites
•At an altitude of about 1100 km, in polar orbits
•With periods of approximately 107 minutes

23. Satellite Navigation Systems
Transit Nav Operation
• The transmitted data includes
• Time code and
• Precise details of the orbit parameters,
• Data are then decoded and the Doppler shift is measured in the
received carrier frequency.
• The information is then evaluated in a computer controlled system, in
the manner depicted below

24. Satellite Navigation Systems
• Transit Sat –Nav System Ship’s

25. Satellite Navigation Systems
Transit Sat Nav………
• A satellite continuously transmits messages of precisely 2 minutes
duration on frequencies of 150 and 400 MHz
• Each message consists of 156 words of 39 bits plus one 19 bit word,
making a total of 6103 bits at and equivalent rate of 50.858 bits per
second.
• The first three words define universal time (GMT) and the next 25
words are used for navigation.
• The remaining words are for military purposes and are not decoded

26. Satellite Navigation Systems
Transit Sat Nav……………
• The received frequency will be different to that transmitted due to
the Doppler effect, which depends upon the relative velocity of the
satellite, and the receiver.
• As the satellite approaching the receiver, the received frequency will
be higher than that transmitted
• Mathematically, the Doppler shift is given by
ft – fr = ft (2v/c) Where
• ft = transmitted frequency
• fr = received frequency
• v = relative velocity of source and receiver
• C = 3x 108 m/s.

27. Satellite Navigation Systems
Transit Sat Nav……………
• At the zenith, the relative velocities are momentarily zero,
so that received and transmitted frequencies are the same
so there is no Doppler shift.
• As the satellite recedes, the received frequency falls
• The satellite receiver compares the received frequency
with a highly accurate and stable local frequency of
400MHz to avoid positive and negative shift.

28. Satellite Navigation Systems
Radio Determination Satellite Service (RDSS)
• This commercial system
• Used to report accurate information about the location of
mobile units back to transport operators’ headquarters.
• It is suitable for use on road vehicles, railway trains, aircraft
or boats and can provide positional fixes accurate to less
than 10 metres
• Provision is also made to sms between headquarters and
the mobile user.

29. Satellite Navigation Systems
Radio Determination Satellite Service (RDSS)………
• The system operates through either low earth orbit (LEO) or
geostationary satellites (GEO)
• Using either the standard LORAN (Long Range Aid to Navigation),
TRANSIT or GPS positioning services.

30. Satellite Navigation Systems
Automatically Dependent Surveillance Broadcasting (ADS-B)
• ADS-B OUT is a surveillance technology that allows suitably
equipped aircraft to broadcast their identity, precise location and
other information derived from the relevant on-board avionics
systems (such as GNSS and pressure altimeters) through a ADS-B
modified Mode S Transponder to ATC (Air Traffic Control).

31. Satellite Navigation Systems
Automatically Dependent Surveillance Broadcasting (ADS-B)
• Aircraft that are equipped with ADS-B IN will be able to receive this information
to provide situational awareness and allow self-separation. ADS-B transponders
get their positions from the GNSS constellation (GNSS, i.e. GPS, Galileo).
• Simultaneously they broadcast their own positions and other data to any aircraft
or ground station equipped to receive it. Unlike radar technology, ADS-B accuracy
does not degrade with range, atmospheric conditions or target audience. It is also
able to update the ATC situation display more frequently than a traditional radar

32. Satellite Navigation Systems

33. Satellite Navigation Systems
Global Positioning System (GPS):
• Consists of 24 satellites that broadcast signals containing information
about their positions and the time that each signal is sent.
• A GPS receiver processes signals from at least four satellites to
determine the receiver’s position to high accuracy (approximately 10
metres)
• The basic concept used by GPS system and receiver is the consistency
of the speed of light.

34. Satellite Navigation Systems
Global Positioning System (GPS):
• GPS satellite signals travels at the speed of light C = 3 x 108 m/s.
• Distance covered by the signal to reach the receiver is d = C ∆t, where
∆t is the time interval between transmission and reception.
• For example, if the signal is transmitted at 10:36:02.0000453297 (it is
read as 10:36 AM plus 2.0000453297 s) and received at
10:36:02.0000821946, then ∆t = 0000368649s.
• Therefore, the distance between the GPS satellite and the GPS
receiver is d = C ∆t = 11059.5 m.

35. Satellite Navigation Systems
Global Positioning System (GPS):
• The receiver must be able to receive at least four GPS signals
simultaneously
• These allow it to calculate the four unknowns: x, y, and z coordinates
of the receiver, and the correct time

36. Satellite Navigation Systems
Illustration of Global Positioning System
d1
d2
d3
EARTH
d4