Navigational Aid

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Navigational AidA navigational aid (also known as aid to navigation, ATON, or navaid) is any sort of marker which aids the traveler

in navigation; the term is most commonly used to refer to nautical or aviation travel. Common types of such aids

include lighthouses, buoys, fog signals, and day beacons.

According to the glossary of terms in the United States Coast Guard Light list, an Aid to Navigation is any device

external to a vessel or aircraft specifically intended to assist navigators in determining their position or safe course,

or to warn them of dangers or obstructions to navigation.

Instrument Landing SystemAn instrument landing system (ILS) is a ground-based instrument approach system that provides precision guidance

to an aircraft approaching and landing on a runway, using a combination of radio signals and, in many cases, high-

intensity lighting arrays to enable a safe landing during instrument meteorological conditions (IMC), such as

low ceilings or reduced visibility due to fog, rain, or blowing snow.

Instrument approach procedure charts (orapproach plates) are published for each ILS approach, providing pilots

with the needed information to fly an ILS approach during instrument flight rules (IFR) operations, including the

radio frequencies used by the ILS components or navaids and the minimum visibility requirements prescribed for

the specific approach.
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Radio-navigation aids must keep a certain degree of accuracy (set by international standards of CAST/ICAO); to

assure this is the case, flight inspection organizations periodically check critical parameters with properly equipped

aircraft to calibrate and certify ILS precision.

LocalizerIn aviation, a localizer (LOC) is one of the components of an Instrument Landing System (ILS), and it provides

runway centerline guidance to aircraft. In some cases, a course projected by localizer is at an angle to the runway

(usually due to obstructions around the airport). It is then called a Localizer Type Directional Aid (LDA). Localizers

also exist in stand-alone instrument approach installations and are not always part of an ILS. The localizer is placed

about 1,000 feet from the far end of the approached runway. Its useful volume extends to 18 NM for the path up to

10 degrees either side of the course. For an angle of 35 degrees either side of the course the useful volume of thelocalizer extends up to 10 NM. Horizontal guidance gets more accurate the closer you fly to the localizer station.

Localizer approaches have their specific weather minimums found on approach plates.
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GLIDE SLOPE

A glide slope (GS) or glide path (GP) antenna array is sited to one side of the runway touchdown zone. The GP

signal is transmitted on a carrier frequency between 328.6 and 335.4 MHz using a technique similar to that of the

localizer. The centerline of the glide slope signal is arranged to define a glide slope of approximately 3 above

horizontal (ground level). The beam is 1.4 deep; 0.7 below the glideslope centerline and 0.7 above the glideslope

centerline.

Terminal DMEA terminal DME, referred to as a TDME in navigational charts, is a DME that is designed to provide a 0 reading at

the threshold point of the runway, regardless of the physical location of the equipment. It is typically associated

with ILSor other instrument approach.

Marker beaconA marker beacon is a particular type ofVHF radio beacon used in aviation, usually in conjunction with

an instrument landing system (ILS), to give pilots a means to determine position along an established route to a

destination such as a runway. From the 1930s until the 1950s, markers were used extensively along airways to

provide an indication of an aircraft's specific position along the route, but from the 1960s they have become

increasingly limited to ILS approachinstallations. They are now very gradually being phased out of service,
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especially in more developed parts of the world, as GPS and other technologies have made marker beacons

increasingly obsolete.There are three types of marker beacons that may be installed as part of their most common

application, an Instrument Landing System:

Outer markerThe Outer Marker, which normally identifies the final approach fix (FAF), is situated on the same course/track as

the localizer and the runway centerline, 4 to 7 nautical miles[citation needed]

before the runway threshold. It is typically

located about 1 NM (2 km) inside the point where the glideslope intercepts the intermediate altitude and transmits a

400 Hz tone signal on a low-powered (3 watts), 75MHz carrier frequency. Its antenna is highly directional, and is

pointed straight up. The valid signal area is a 2,400 ft (730 m) 4,200 ft (1,280 m) ellipse.When the aircraft passes

over the outer marker antenna, its marker beacon receiver detects the signal. The system gives the pilot a visual

(blinking blue outer marker light) and aural (continuous series of audio tone morse code-like 'dashes') indication.

Some countries, such as Canada, have abandoned marker beacons completely, replacing the outer marker with

a non-directional beacon (NDB), and more recently with GPS fixes. In the United States, the outer marker has often

been combined with an NDB to make a Locator Outer Marker (LOM). Some ILS approaches have no navigation aid

at all situated at the final approach fix, but use other means, such as VOR radial intersections, distance measuring

equipment (DME), GPS, or radar fixes, to identify the position.

Middle markerA middle marker works on the same principle as an outer marker. It is normally positioned 0.5 to 0.8 nautical miles

(1 km) before the runway threshold. When the aircraft is above the middle marker, the receivers amber middle

marker light starts blinking, and a repeating pattern of audible morse code-like dot-dashes at a frequency of

1,300 Hz in the headset. This alerts the pilot that the CAT Imissed approach point (typically 200 feet (60 m) above
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the ground level on the glideslope) has been passed and should have already initiated the missed approach if one of

several visual cues has not been spotted.

Inner markerSimilar to the outer and middle markers; located at the beginning (threshold) of the runway on some ILS approach

systems (usually Category II and III) having decision heights of less than 200 feet (60 m) AGL. Triggers a

flashing white light on the same marker beacon receiver used for the outer and middle markers; also a series of

audio tone 'dots' at a frequency of 3,000 Hz in the headset.

Non-directional beacon

FixesNDBs have long been used by aircraft navigators, and previously mariners, to help obtain a fix of their geographic

location on the surface of the Earth. Fixes are computed by extending lines through known navigational reference

points until they intersect. For visual reference points, the angles of these lines can be determined by compass; the

bearings of NDB radio signals are found using RDF equipment.

VHF omnidirectional range (VOR)VOR, short for VHF omnidirectional radio range, is a type of short-range radio navigation system for aircraft,enabling aircraft to determine their position and stay on course by receiving radio signals transmitted by a network

of fixed ground radio beacons, with a receiver unit. It uses radio frequencies in the very high frequency (VHF) band

from 108 to 117.95 MHz. Developed in the US beginning in 1937 and deployed by 1946, VOR is the standard air

navigational system in the world, used by both commercial and general aviation. There are about 3000 VOR stations

around the world. A VOR ground station sends out a master signal, and a highly directional second signal that varies

in phase 30 times a second compared to the master. This signal is timed so that the phase varies as the secondary
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antenna spins, such that when the antenna is 90 degrees from north, the signal is 90 degrees out of phase of the

master. By comparing the phase of the secondary signal to the master, the angle (bearing) to the station can be

determined. This bearing is then displayed in the cockpit of the aircraft, and can be used to take a fix as in

earlier radio direction finding (RDF) systems, although it is, in theory, easier to use and more accurate. This line of

position is called the "radial" from the VOR. The intersection of two radials from different VOR stations on a chart

provides the position of the aircraft. VOR stations are fairly short range, the signals have a range of about 200

miles.VOR stations broadcast a VHF radio composite signal including the station's identifier, voice (if equipped),

and navigation signal. The identifier is typically a two- or three-letter string in Morse code. The voice signal, if used,

is usually the station name, in-flight recorded advisories, or live flight service broadcasts. The navigation signal

allows the airborne receiving equipment to determine a magnetic bearing from the station to the aircraft (direction

from the VOR station in relation to the Earth's magnetic North at the time of installation). VOR stations in areas of

magnetic

CVOR

The conventional signal encodes the station identifier, i(t), optional voice a(t), and navigation reference signal

in, c(t), the isotropic(i.e. omnidirectional) component. The reference signal is encoded on an F3 subcarrier (color).

The navigation variable signal is encoded by mechanically or electrically rotating a directional, g(A,t), antenna to

produce A3 modulation (grayscale) Receivers (paired color and grayscale trace) in different directions from the

station paint a different alignment of F3 and A3 demodulated signal.
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DVOR

The doppler signal encodes the station identifier, i(t), optional voice, a(t), and navigation variable signal in, c(t), an

isotropic (i.e. omnidirectional) component. The navigation variable signal is A3 modulated (grayscale). The

navigation reference signal is delayed, t+, t-, by electrically revolving a pair of transmitters. The cyclic blue shift, and

corresponding red shift, as a transmitter closes on and recedes from the receiver results in F3 modulation (color).

The pairing of transmitters offset equally high and low of the isotropic carrier frequency produce the upper and

lower sidebands. Closing and receding equally on opposite sides of the same circle around the isotropic transmitter

produce F3 subcarrier modulation, g(A,t).

Distance measuring equipment(DME)Distance measuring equipment (DME) is a transponder-based radio navigation technology that measures slant

range distance by timing the propagation delay ofVHF or UHF radio signals.

Developed in Australia, it was invented by Edward George "Taffy" Bowen while employed as Chief of the Division

of Radiophysics of the Commonwealth Scientific and Industrial Research Organisation (CSIRO). Another

engineered version of the system was deployed by Amalgamated Wireless Australasia Limited in the early 1950s

operating in the 200 MHz VHF band. This Australian domestic version was referred to by the Federal Department of

Civil Aviation as DME(D) (or DME Domestic), and the later international version adopted by ICAO as DME(I).

DME is similar to secondary radar, except in reverse. The system was a post-war development of the IFF

(identification friend or foe) systems ofWorld War II. To maintain compatibility, DME is functionally identical tothe distance measuring component ofTACAN. Aircraft use DME to determine their distance from a land-based

transponder by sending and receiving pulse pairs - two pulses of fixed duration and separation. The ground stations

are typically co-located with VORs. A typical DME ground transponder system for en-route or terminal navigation

will have a 1 kW peak pulse output on the assigned UHF channel.

A low-power DME can also be co-located with an ILS glide slope antenna installation where it provides an accurate

distance to touchdown function, similar to that otherwise provided by ILS Marker Beacons.
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Very high frequency

Very high frequency (VHF) is the radio frequency range from 30 MHz to 300 MHz. Frequencies immediately below

VHF are denoted high frequency (HF), and the next higher frequencies are known as ultra high frequency (UHF).

The frequency allocation is done by ITU.These names referring to high-end frequency usage originate from mid-20th century, when regular radio service

used MF, Medium Frequencies, better known as "AM" in USA, below the HF. Currently VHF is at the low-end of

practical frequency usage, new systems tending to use frequencies in SHF and EHF above the UHF range.

See Radio spectrum for full picture.

Common uses for VHF are FM radio broadcast, television broadcast, land mobile stations (emergency, business,

private use and military), long range data communication with radio modems, amateur radio, marine

communications, air traffic control communications and air navigation systems (e.g. VOR, DME & ILS).

Ultra high frequency

Ultra-high frequency (UHF) designates the ITU radio frequency range ofelectromagnetic waves between

300 MHz and 3 GHz (3,000 MHz), also known as the decimetre band ordecimetre wave as the wavelengths range

from one to ten decimetres (10 cm to 1 metre). Radio waves with frequencies above the UHF band fall into the SHF

(super-high frequency) and EHF (extremely high frequency) bands, all of which fall into the microwave frequency

range. Lower frequency signals fall into the VHF (very high frequency) or lower bands. SeeElectromagnetic

spectrum and Radio spectrum for a full listing of frequency bands.
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General Electronics is basically all about general electronic systems which is used in CAA.These include variousequipment which make communication possible from ground to air and voice versa.Some of the major equipments

are as follows:

DVLS(Digital voice logging System):

It is used to store the communication between pilot and the controller ASC marathon , german based company It is a limux based machine It consists of two HDD and two DVD-ram drives Multimedia recording for traditional telephony and radio , VoIP ,trunk radio Analog inputs: 4-192 channels Digital Inputs: 4-120 channels VoIP:4-32 Channels (active) , 4-120 (passive) There are generally two units installed one is active and the other is on hot standby.


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HISTORY OF VLS

The original voice logging system was a large analog taperecorder developed in 1950 by MAGNASYNC.In 1953

MAGNASYNC corp. sold 300 voice loggers to US airforce.In 1980 the first digital voice logging system were

developed and shrank to the size of large pc.The original computerized system were designed and manufactured by

EVENTIDE,Eyretel and dictathone.in 1996 mercom systems which was purchased by VERINT in July 2006 ,

introduced audio log the first window based voice logging system.

PA Systems

The public address systems(PA systems)is an electronic amplification system with microphones, pre amplifiers and

signal routers which allow variation in sound levels, amplifiers to increase the sound level and intensity.Loud

speakers are placed in convenient locations around the broadcasting area.The user speaks in the microphone and thesound is transmitted to the amplifier then cables and finally to the loudspeaker.

General Electronics is basically all about general electronic systems which is used in CAA.These include various

equipment which make communication possible from ground to air and voice versa.Some of the major equipments

are as follows:


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Telecommunication

Telecommunication is the transmission ofinformation over significant distances to communicate.

In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore

telegraphs, signal flags, and optical heliographs, or audio messages such as coded drumbeats, lung-blown horns, andloud whistles.

In modern times, telecommunications involves the use of electrical devices such as the telegraph, telephone,

and teleprinter, as well as the use of radio and microwave communications, as well as fiber optics and their

associated electronics, plus the use of the orbiting satellites and the Internet.

A revolution in wireless telecommunications began in the 1900s (decade) with pioneering developments in wireless

radio communications by Nikola Tesla and Guglielmo Marconi. Marconi won the Nobel Prize in Physics in 1909 for
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his efforts. Other highly notable pioneering inventors and developers in the field of electrical and electronic

telecommunications include Charles Wheatstone and Samuel Morse (telegraph), Alexander Graham

Bell (telephone), Edwin Armstrong, and Lee de Forest (radio), as well as John Logie Baird and Philo

Farnsworth (television).
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High frequency

The ionosphere often refracts HF radio waves quite well. This phenomenon is known as skywave propagation.

Because of these characteristics this range is extensively used for medium and long range radio communication.

However, suitability of this portion of the spectrum for such communication varies greatly with a complexcombination of factors

Sunlight/darkness at site of transmission and reception Transmitter/receiver proximity to terminator Season Sunspot cycle Solar activity Polar auroraThese and other factors contribute, at each point in time for a given communication path, to a

Maximum usable frequency (MUF) Lowest usable high frequency (LUF) and a Frequency of optimum transmission (FOT)The maximum usable frequency regularly drops below 10 MHz in darkness during the winter months, while in

summer during daylight it can easily surpass 30 MHz. It depends on the angle of incidence of the waves; it is lowest

when the waves are directed straight upwards, and is higher with less acute angles. This means that at longer

distances, where the waves graze the ionosphere at a very blunt angle, the MUF may be much higher. The lowest

usable frequency depends on the absorption in the lower layer of the ionosphere (the D-layer). This absorption is
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stronger at low frequencies and is also stronger with increased solar activity (for example in daylight); total

absorption often occurs at frequencies below 5 MHz during daytime. The result of these two factors is that the

usable spectrum shifts towards the lower frequencies and into the Medium Frequency (MF) range during winter

nights, while on a day in full summer the higher frequencies tend to be more usable, often into the lower VHF range.

HF BAND CHART

CHANNELS BAND A BAND B BAND C BAND D HF/RI intl.

1. 3997.0 2514.0 2815.0 2923.0 2923.02. 5132.0 3825.0 5027.5 2601.0 3467.03. 7738.0 6840.0 7425.0 --------- 5601.04. 8090.0 3297.5 2727.5 --------- 5658.05. 10565.0 5252.5 3960.0 --------- 10018.06. 11580.0 8172.5 8567.0 --------- 13288.07. --------- 6903.0 3181.0 --------- ---------8. --------- --------- 5022.0 --------- ---------9. --------- --------- 7415.0 --------- ---------10. --------- --------- --------- --------- ---------
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RadarRadar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of

objects. It can be used to detect aircraft, ships, spacecraft, guided missiles,motor vehicles, weather formations, and
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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.

Radar was secretly developed by several nations before and during World War II. The termRADAR was coined in

1941 by the United States Navy as an acronym forRAdio Detection AndRanging.[1][2]

The term radarhas since

entered English and other languages as the common noun radar, losing all capitalization.

The modern uses of radar are highly diverse, including air traffic control, radar astronomy, air-defense

systems, antimissile systems; marine radars to locate landmarks and other ships; aircraft anticollision systems; ocean

surveillance systems, outer space surveillance and rendezvous systems; meteorological precipitation monitoring;

altimetry and flight control systems; guided missile target locating systems; and ground-penetrating radar for

geological observations. High tech radar systems are associated with digital signal processing and are capable of

extracting objects from very high noise levels.

Primary Surveillance Radar (PSR)

The first ATC radars used in Australia were WAR times air defense units which were used experimentally. These

radars were of type that later became known as PRIMARY RADARS. That is,they worked on the well known battle

of Britain principle in which radar transmitter sends out a pulse of radio energy of which a very small portion is

reflected from the surface of the target back to the radar receiver. The azimuth orientation of the radar antennaprovides the bearing of the aircraft from the ground station and the time taken for the pulse to reach the target and

return provides a major of the distance of the target from the ground station. The bearing and the distance of the

target can then be converted into a ground position for display to ATC.Target elevation is not normally measured

by ATC PSRs.The advantage of PSR is that it operates totally independently of target aircraft that is no action from

the aircraft is required for it to provide a radar return.
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Secondary surveillance radar

Secondary surveillance radar (SSR) is a radar system used in air traffic control (ATC), that not only detects and

measures the position of aircraft i.e. range and bearing, but also requests additional information from the aircraft

itself such as its identity and altitude. Unlike primary radar systems that measure only the range and bearing oftargets by detecting reflected radio signals, SSR relies on targets equipped with a radar transponder, that replies to

each interrogation signal by transmitting a response containing encoded data. SSR is based on the

military identification friend or foe (IFF) technology originally developed during World War II, therefore the two

systems are still compatible. Monopulse secondary surveillance radar (MSSR), Mode S, TCAS and ADS-B are

similar modern methods of secondary surveillance.

1. AFIT2. Tracker3. Micro system trouble shooter4. Frequency counter5. Power meter6. Synthesizer7. VHF switch8. Relay actuator9. System power supplier
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10. Combinational system S-64511. Curved tracer12. EPROM programmer uniside13. Text bench of RICS-TXm-420014. ABI linear master compact15. ABI chip master compact16. Component analyzer17. Relative humidity & temp. tester18. ROBIN microwave leakage tester19. BK precision cap. Meter20. BK precision inductance meter21. Fluke scope meter22. Fluke multimeter23. Tool kit xcellite24. Soldering station25. Huntron protrack-I26. DATAMAN universal EPROM programmer27. Disordering station28. HUNTON scanner29. Digital oscilloscope30. Battery capacity tester31. TRISCO-Digital battery load tester32. Spectrum analyzer33. ERSA infrared rework station34. ERSA solder/fumes extractors.

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