PRESENTATION ON METHODS OF NAVIGATION SUBMITTED BY TARIQUDDIN S. AHMED Final Year, ECE

Outline 1. Introduction 2. Radio navigation 3. Inertial navigation 4. Satellite navigation 5. Radar navigation 6. Integrated navigation

1. Introduction Objectives of navigation: ◦ Know your position ◦ Efficient use of fuel ◦ Maintain a schedule ◦ Avoid other traffic ◦ Avoid ground-to-air missiles and anti-aircraft artillery (known sites) ◦ Minimize exposure to enemy radar

1.1 Main methods of navigation Classic dead-reckoning using air data (speed, altitude) and magnetic (bearing) coupled with LORAN-C. Radio navigation Inertial navigation Satellite navigation Radar navigation Combinations of the above (integrated)

1.2 Principles of navigation Basic navigation parameters: ◦ Altitude (barometric or radar) ◦ Speed in the X, Y and Z axes  Indicated air speed (IAS), Mach number (M), and true air speed (TAS) ◦ Heading and track ◦ Position in latitude and longitude ◦ Way-points

2.Radio navigation Use of the classic dead-reckoning method of navigation, based upon the parameters presented in the previous diagram, is subject to heading errors and en route wind affects that lead to along-track and across-track errors. Since the 1930’s, radio beacons and navigation aids have greatly improved navigation by providing a fixed set of references points.

2.1 Radio navigation Radio navigation aids include: ◦ VHF omnirange (VOR) ◦ Distance-measuring equipment (DME) ◦ Non-distance beacons (NDB) ◦ Tactical air navigation (TACAN) ◦ VORTAC (combined TACAN and VOR) ◦ Long range navigation (LORAN-C)

2.2 VHF omnirange (VOR) VOR stations provide bearing information relative to the aircraft position. VOR stations operate in the MHz band with a channel spacing of 50 kHz or 100kHz. Each station transmits its identification via a Morse code modulated tone. A reference 30 Hz signal is FM modulated onto the carrier. A secondary signal is sent by a directed (cardioid) antenna that spins at 30 rev/sec.

2.2.1 VOR bearing

2.3 Distance measurement equipment (DME) Provides the distance from the station by measuring the time difference between the interrogation pulses and the response. Often installed near VOR stations so as to provide combined bearing and distance.

2.4 Non-distance beacons (NDB) The signal only includes bearing information. On board automatic direction finding equipment is required to get the bearing. The most widely spread beacons in use today.

2.5 Tactical air navigation (TACAN) A navigation system used by military aircraft. Operates on UHF channels between MHz. More precise than VOR/DME.

2.6 Combined VOR / TACAN (VORTAC) Provides interoperability between civil and military aircraft. Especially useful for large military aircraft that frequently fly civil aviation routes.

2.7 LORAN- C LORAN is a terrestrial navigation system using low frequency radio transmitters that use the time interval between radio signals received from three or more stations to determine the position of ship or an aircraft. The current version of LORAN in use is LORAN-C which operates in the low frequency of the EM spectrum from 90 to 110 KHz.

2.7.1 Hyperbolic LORAN- C

3. Inertial navigation (IN) An inertial navigation system includes at least a computer and a platform or module containing accelerometers and gyroscopes, or other motion- sensing devices. The INS is initially provided with its position and velocity from another source (a human operator, a GPS satellite receiver, etc.), and thereafter computes its own updated position and velocity by integrating information received from the motion sensors. The advantage of an INS is that it requires no external references in order to determine its position, orientation, or velocity once it has been initialized.

3.1 IN principle of operation AccelerometersGyroscopes Calculate the components of acceleration Initial values Acceleration in x, y and z Initial values Speed in x, y and z Coordinates in x, y and z

4. Global navigation satellite systems (GNSS) Three systems: ◦ GLONASS ◦ Galileo ◦ GPS

4.1 GLONASS A system of the former Soviet Union First satellite launched in 1982, system of 24 satellites completed in ◦ Currently the system is only about 25% operational.

4.2 Galileo A European system of scheduled to enter service around ◦ 30 satellites planned so as to provide better coverage for higher (polar) latitudes. ◦ Independent of GPS (in times of war)

4.3 GPS American system Operational since ◦ 24 satellites, arranged so that a minimum of 5 are always visible anywhere on earth.

4.3.1 GPS - Principles of operation Control segment ◦ ground-based control stations ◦ monitoring stations ◦ antennas (dishes) Space segment ◦ the 24 satellites User segment ◦ ships, automobiles, airplanes, portable devices, phones

4.3.2 GPS - Principles of operation

4.3.3 GPS - Principles of operation Basic ranging and triangulation is used to compute a receivers position. ◦ Each satellite transmits a unique identifier code and a precise time stamp. ◦ The ground based control / monitoring stations keep the precise time and positional information of each satellite up-to-date. ◦ The receiver can accurately pin-point its position by knowing the signal time travel from at least 4 satellites.

5. RADAR NAVIGATION Radar is an object-detection system which uses electromagnetic waves specifically radio waves — to determine the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish, or antenna, transmits pulses of radio waves or microwaves which bounce off any object in their path. The object returns a tiny part of the wave's energy to a dish or antenna which is usually located at the same site as the transmitter.

5.1 Basic Diagram

6. Integrated Navigation By integrating various means of navigation, better performance can be achieved.

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