Aesi Radio

7/18/2019 Aesi Radio

1/41

Context:

1. RADOME

2. FREQUENCY SYNTHESIZER

3. PHASE LOCKED LOOP

. ANTENNA TUNIN! UNIT

". DUPLE#ER

$. %&'e() *+,n-,*e o/ 0e,0t /,n,n ,n +((+

. Ce4(+ Tee*0one S56te)

7. 8ATTERIES

9. D%OR

1. !ROUND PRO#IMITY ;ARNIN! SYSTEM

11. FLI!HT CONTROL SYSTEM

12. COMPUTER SYSTEM APPLICATION

13. FREQUENCEY OF OPERATION

1. INTERFERENCE

1". SOLDERIN! TECHNIQUE

1$. MICRO;A%E DE%ICES

1.SATELLITE COMMUNICATION

17. COCKPIT %OICE RECORDER


2/41

RADOME

A +(o)e(the word is a contraction of +((+and o)e) is a structural, weatherproo

enclosure that protects a microwave (e.g. radar) antenna.

The radome is constructed of material that is mechanically strong and minimally

attenuates the electromagnetic signal transmitted or received by the antenna. In other

words, the radome is transparent to radar or radio waves.

Radomes can be constructed in several shapes (spherical, geodesic, planar, etc.)

depending upon the particular application using various construction materials

(fiberglass, PT! "coated fabric, etc.).

A radome prevents rise in #$%R by covering the antenna&s e'posed parts with a stur

weatherproof material, typically fiberglass, which eeps debris or ice away from theantenna to prevent any serious issues.

or radar dishes, a single, large, ball"shaped dome also protects the rotational

mechanism and the sensitive electronics, and is heated in colder climates to prevent

icing.

The airborne radome must be strong enough to form a part of the ac structure and

usually must be designed to conform to the aerodynamic shape of the aircraft, missile

or space vehicle in which it is to operate.

A radome permits a ground"based radar antenna to operate in the presence of high

winds. It also prevents the ice formation on the antenna. The shape of the RA*+!

for a ground"based antenna is usually a portion of a sphere. The sphere is a good

mechanical structure and offers aerodynamic advantage in high winds.

Radomes protect the antenna surfaces from weather or conceal antenna electronic

e-uipment from public view. They also protect nearby personnel from being

accidentally struc by -uicly"rotating antennas.


3/41

FREQUENCY SYNTHESIZER

A /+e>4en-5 65nt0e6,?e+is an electronic system for generating any of a range

of fre-uencies from a single fi'ed time base or o6-,(to+.

They are found in many modern devices, including +(,o +e-e,@e+6 )o',etee*0one6 +(,otee*0one6 6(te,te +e-e,@e+6 !PS 656te)6, etc.

A fre-uency synthesier can combine fre-uency multiplication, fre-uency division,

and fre-uency mi'ing (the fre-uency mi'ing process generates sum and difference

fre-uencies) operations to produce the desired output signal.

re-uency $ynthesier can also be used as a fre-uency converter, which uses a phase

loced loop / digital counters in a phase error feedbac system to eep the op runni

in a fi'ed phase relation to the reference signal.

re-uency synthesier are of tBotypes0

a) D,+e-t F+e>4en-5 S5nt0e6,?e+0

The direct synthesier uses a stable crystal oscillator followed by a series of

harmonics multipliers and mi'ers, to provide the range of different op

fre-uencies.

b) In,+e-t F+e>4en-5 S5nt0e6,?e+0

The indirect fre-uency synthesier uses a phase loced loop to give an op whi

is a fraction of that of a stable crystal oscillator.

T0e 65nt0e6,?e+ te-0n,>4e6 *+o@,e ( ene+(to+ B,t0 ex-eent /+e>4en-5 (--4+(-5 (n

6t(',,t5 '4t -(+e/4 e6,n ,6 neee to o@e+-o)e t0e *+o'e) o/ 6*4+,o46 6,n(6 ,n o
http://en.wikipedia.org/wiki/Mobile_telephonehttp://en.wikipedia.org/wiki/Mobile_telephonehttp://en.wikipedia.org/wiki/Mobile_telephone


4/41

PHASE LOCKED LOOP

A *0(6e&o-e oo*or *0(6e o- oo*(P11) is a control systemthat generates an

output signalwhosephaseis related to the phase of an input 2reference2 signal.

It is an electronic circuitconsisting of a variable fre-uency oscillatorand aphase

detector. This circuit compares the phase of the input signal with the phase of the sigderived from its output oscillator and ad3usts the fre-uency of its oscillator to eep th

phases matched.

The signal from the phase detector is used to control the oscillator in a feedbac loop

4onse-uently, a phase"loced loop can trac an input fre-uency, or it can generate a

fre-uency that is a multiple of the input fre-uency.

The former property is used for demodulation, and the latter property is used for

indirect fre-uency synthesis.

A**,-(t,on6

Phase"loced loops are widely employed in radio, telecommunications, computersan

other electronic applications.

They can be used to recover a signal from a noisy communication channel, generate

stable fre-uencies at a multiple of an input fre-uency (fre-uency synthesis).

$ince a single integrated circuitcan provide a complete phase"loced"loop building

bloc, the techni-ue is widely used in modern electronic devices, with output

fre-uencies from a fraction of a hert up to many gigahertes.
http://en.wikipedia.org/wiki/Control_systemhttp://en.wikipedia.org/wiki/Signal_(electrical_engineering)http://en.wikipedia.org/wiki/Phase_(waves)http://en.wikipedia.org/wiki/Electronic_circuithttp://en.wikipedia.org/wiki/Electronic_oscillatorhttp://en.wikipedia.org/wiki/Phase_detectorhttp://en.wikipedia.org/wiki/Phase_detectorhttp://en.wikipedia.org/wiki/Feedback_loophttp://en.wikipedia.org/wiki/Demodulationhttp://en.wikipedia.org/wiki/Frequency_synthesishttp://en.wikipedia.org/wiki/Radiohttp://en.wikipedia.org/wiki/Telecommunicationshttp://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/Frequency_synthesishttp://en.wikipedia.org/wiki/Integrated_circuithttp://en.wikipedia.org/wiki/Control_systemhttp://en.wikipedia.org/wiki/Signal_(electrical_engineering)http://en.wikipedia.org/wiki/Phase_(waves)http://en.wikipedia.org/wiki/Electronic_circuithttp://en.wikipedia.org/wiki/Electronic_oscillatorhttp://en.wikipedia.org/wiki/Phase_detectorhttp://en.wikipedia.org/wiki/Phase_detectorhttp://en.wikipedia.org/wiki/Feedback_loophttp://en.wikipedia.org/wiki/Demodulationhttp://en.wikipedia.org/wiki/Frequency_synthesishttp://en.wikipedia.org/wiki/Radiohttp://en.wikipedia.org/wiki/Telecommunicationshttp://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/Frequency_synthesishttp://en.wikipedia.org/wiki/Integrated_circuit


5/41

P0(6e&o-e oo* 'o- ,(+()

A phase detector compares two input signals and produces an error signal which

proportional to their phase difference. The error signal is then low"pass filtered and used to drive a #4+ which creates

output phase.

The output is fed through an optional divider bac to the input of the system,

producing a negative feedbac loop.

If the outputs phase drifts, the error signal will increase, driving the #4+ phase i

the opposite direction so as to reduce the error.

Thus the output phase is loced to the phase at the other input. This input is calle

the reference.


6/41

Antenn( T4n,n Un,t

An (ntenn( t4ne+, t+(n6&)(t-0or (ntenn( t4n,n 4n,t(ATU) is a device

connected between a radio transmitter or receiver and its antenna to improve the

efficiency of the power transfer between them by matching the impedance of thee-uipment to the antenna.

An antenna tuner matches a transceiver with fi'ed impedance to load impedance

which is unnown, comple' or otherwise does not match.

An AT5 allows the use of one antenna for a broad range of fre-uencies.

The AT5 essentially redirects the reflected energy bac along the feed line and

antenna path. The additional losses come from the inherent losses within the feed

line and antenna itself. $%R causes feed line losses to be multiplied. 1ow loss fee

line would have minimal loss when tuned with an AT5 whereas a 2lossy2 feedlineantenna combination of the same $%R could have significant loss.

%ithout the AT5, $%R from a mismatched antenna could cause reflections of

power bac into the transmitter, which will cause heating in the transmitter and

significant power loss

An AT5 is actually an antenna matching unit, as it is unable to change the resonan

fre-uency of the aerial.

Types of AT50

6. 5ltimate transmatch

7. Pi"8etwor

9. $P4 transmatch

A**,-(t,on

5sed in high power shortwave broadcasting transmitters (:; %


7/41

D4*exe+

A 4*exe+is a device that allows bi"directional communication (both receiving andtransmitting) over a single path.

In case of radar and radio communications systems, it isolates the receiver from the

transmitter while permitting them to share a common antenna. ost radio repeater systems

include a duple'er.

A duple'er must be designed for operation in the fre-uencybandused by the receive

and transmitter, and must be capable of handling the outputpowerof the transmitter.

A duple'er must provide ade-uate re3ection of transmitter noiseoccurring at the rece

fre-uency, and must be designed to operate at, or less than, the fre-uency separationbetween the transmitter and receiver.

A duple'er must provide sufficient isolation to prevent receiver desensitiation.

There are several different ways to build a duple'er. The hybrid ring, cavity notch an

band pass =and re3ect design

;HY ARE DUPLE#ERS USED

Radio receivers can be damaged if high level R signals, lie those directly from a

transmitter output, are applied to the receiver antenna.

Additionally, receivers may become >desensitied? (or >de"sensed?) and not receive

wea signals when high noise levels or another signal near the receive fre-uency is

present at the receivers antenna input.

+bviously, radio receivers and transmitters cannot be directly connected to the same

antenna without some device being used to0


8/41

push"to"tal? manner used in non"duple' (or >simple'?) operating modes.

The radio system must use two fre-uencies per >channel? to use the inds of duple'ers we

discussing. *uple'ers are the devices that allow a mobile telephone to operate lie a wir

telephone, with either or both people speaing at any time without using a microphone swi

to enable the radio transmitters.


9/41

%&'e() *+,n-,*e o/ 0e,0t /,n,n ,n +((+:

#"=eam is a radar scan pattern modus in which separate radar transmitters feed two antenna

which produce vertical fan beams.

+ne antenna is tilted from the horiontal by appro'imately 9; degrees. This has the effect

displacing the resulting fan"shaped elevation beam by the same amount from the vertical.

This beam, in combination with the vertical beam produced by the companion antenna, thu

provides the means for height"finding by the #"beam techni-ue.

Figure: The pattern of the upper antenna is distorted from the horizontal one.

Target elevation is deduced by comparing the time differences in echo response e'perienced

by the two antennas.


10/41

Ce4(+ Tee*0one S56te)

4ellular telephone, sometimes called mobile telephone, is a type of short wave analog or

digital telecommunication in which a subscriber has a wireless connection from a mobile

telephone to a relatively nearby transmitter. The transmitter&s span of coverage is called a

-e.

E#TRA

The first cellular telephone for commercial use was approved by the ederal 4ommunicatio4ommission (44) in 6@9.

%ith cellular radio we use a simple he'agon to represent a comple' ob3ect0 the geographica

area covered by cellular radio antennas. These areas are called cells.

5sing this shape let us picture the cellular idea, because on a map it only appro'imates the

covered area. %hy a he'agon and not a circle to represent cellsB

%hen showing a cellular system we want to depict an area totally covered by radio, withou

any gaps. Any cellular system will have gaps in coverage, but the he'agonal shape lets us

more neatly visualie, in theory, how the system is laid out. 8otice how the circles below

would leave gaps in our layout.


11/41

8ATTERIES:

C(*(-,t5:

The electrical charge effectively stored in a primary or secondary battery and available for

transfer during discharge. 5sually e'pressed in ampere"hours (Ah) orilli"ampere"hours (mAh).

Ene+5 en6,t5:

A measure of the energy storage efficiency of a battery, usually e'pressed in watt"hours per

ilogram (%hg). In simple, ene+5 en6,t5 )e(n6 0oB )4-0 ene+5 ,6 6to+e '5 one

,o+() o/ '(tte+5.

Type of =attery !nergy density (%"hrCg)

Le( A-, 77

N,-e C(),4) DD

S,@e+ Z,n- 66;

Ex()*e /o+ %OR:

=efore we loo in detail at how the system wors the following e'ample illustrates theprinciple and should mae it easier to understand.

Thin of a lighthouse at sea and imagine the white light rotating at a speed of one revolutio

per minute (E; seconds). !very time this white narrow beam passes through agnetic 8ort

a green omnidirectional light flashes. +mnidirectional means that it can be seen from any

position around the lighthouse. If we are situated somewhere in the vicinity of the light

sources and are able to see them, we can measure the time interval from the green light flas

until we see the white light. The elapsed time is directly proportional to our position line in

relation to the lighthouse.


12/41

Do**e+ %OR


13/41

!+o4n P+ox,),t5 ;(+n,n S56te)

ig0 !nhanced round Pro'imity %arning $ystem

The *4+*o6e of a ground pro'imity warning system is to provide aural and

visual signals to the pilot when the aircraft is in danger of impacting with the

ground, unless corrective action is taen.

Joint aviation re-uirements are that all turbine"powered aircraft having a

ma'imum certificated tae"off weight greater than :K;; g and seating for

more than nine passengers must be e-uipped with a P%$.

There are three types of P%$ currently in use0 '(6,- (@(n-e (n

en0(n-e.


14/41

8(6,- !P;S

The basic P%$ has /,@e )oe6 o/ o*e+(t,onwhich re-uire the /ooB,n

6o4+-e ,n*4t6:

1. R(,o (t,)ete+0 Accurate measurement of height above ground level

is provided by the radio altimeter.

2. Cent+( (,+ (t( -o)*4te+0 =arometric pressure is integrated by the

P%$ to compute descent rates.

3. ILS ,e*(t0 +e-e,@e+0 The P%$ is re-uired to give warning of

descent below the glidepath during a landing approach.

4. A**+o(-0 -on/,4+(t,on0 The landing gear and flaps positions are

necessary inputs to the system during the approach to land.

The P%$ must be active between 2" /t. (n " /t.above ground level.

O*e+(t,n )oe6:

Moe one ex-e66,@e e6-ent +(te:

5sing radar altitude and rate of decent information the P%$ monitors the

flight profile when an ac is within 2" /t. terrain.

If e'cessive rate of descent develops at the current altitude agl


15/41

Moe t0+ee (t,t4e o66 (/te+ t(e&o// o+ o&(+o4n:

5sing ac speed, radar altitude, barometric altitude and ac configuration

changes, P%$ recognies tae"off or missed approach.

P%$ compares any loss of barometric altitude to pea altitude gain. %hen

this is roughly 6;L,the red P%$ warning lamp will illuminate and voicealert DONT SINKGwill be heard.

%hen positive rate of climb is establish, the warning lamp will e'tinguish

and the voice alert will cease.

+*!"9 is disabled when ac reaches6;;; ft. above ground.

Moe /o4+ 4n6(/e te++(,n -e(+(n-e:

5sing air speed, altitude, rate of descent and aircraft configuration P%$

will alert the pilot to insufficient terrain clearance. +*!"D develops a floor below the ac during climb out, which continues

until ;; ft. above the ground.

If the ac penetrates this floor the red P%$ warning lamp will illuminate

and voice alert TOO LO; TERRAINGwill be heard.

+nce the ac is safely bac above the floor the warning lamp will e'tinguish

and the voice alert will cease.

Moe /,@e (,+-+(/t 'eoB t0e ILS ,e6o*e:

P%$ monitors the flight path in relation the glideslope center line while onthe I1$ final approach course.

+*!": is enabled when an ac starts receiving signal from the glideslope.

If the ac goes some precise value below the glideslope center"line, ()'e+

!P;S !S lamp will illuminate and voice alert !LIDE SLOPEG is heard.

+nce the ac comes bac to the correct position on the center line of the

glide slope signal, the warning lamp will e'tinguish and the voice alert will

cease.

Moe 6,x 6,t4(t,on( (B(+ene66:

A disadvantage of the basic P%$ is that it does not differentiate between

modes 6 to D, because it gives the same warning in each case. It is, of course,


16/41

useful for the pilot to now the cause of the warning when responding to it.

FLI!HT CONTROL SYSTEM

An ac must have a control system that allows the pilot to manoeuver the ac

in three ma3or a'is (1ateral, 1ongitudinal and #ertical). In addition, thespeed of the ac must also be controlled.

The standard method of achieving this control is to provide a set of control

surfaces for pitch, roll and yaw, allowing control of the direction of travel.

our primary controls of an ac are0

a. !levators for control in pitch.

b. Rudder for control in yaw.

c. Ailerons for control in speed.

d. Throttle for control in speed.

!ach control surface are located near the e'tremities of the ac, so utiliing

the largest moment arm about the center of gravity / thus allowing surfaces

to be small in sie.

In fighter ac, computer control can be used to control an unstable ac which

would otherwise be impossible to fly.

In large or fast ac, the forces re-uired to move the control surfaces are too

high for the pilot to operate them, and a system of power operation or power

assistance is re-uired, using power actuators.

The control system must be designed in such a way that there is e'tremely

small possibility of total failure.

TYPES

6. echanical 4ontrol

7. Hydro echanical 4ontrol9. ly"by"%ire 4ontrol

D. 4omputer 4ontrol


17/41

COMPUTER SYSTEM APPLICATION

A computer is a programmable machine designed to se-uentially and

automatically carry out a se-uence of arithmetic or logic operations.

The particular se-uence of operations can be changed readily, allowing the

computer to solve more than one ind of problem.

4onventionally a computer consists of some form of memory for data

storage, at least one element that carries out arithmetic / logic operations /

a se-uencing / control element that can change the order of operations

based on the information that is stored.

A peripheral device allows information to be entered from e'ternal source /

allows the result of operation to be sent out.

A computer processing unit e'ecutes series of instruction that mae it read,

manipulate / then store data. 4onditional instructions change the se-uence

of instructions as a function of the current state of the mc or, tis

environment.

odern computers based on integrated cts.are millions of billions of times

more capable than the early machines, and occupy a fraction of the space.

$imple computers are small enough to fit into mobile devices and can be

powered by a small battery.

The embedded computers found in many devices from P9 players to

fighter ac and from toys to industrial robots are the most numerous.


18/41

SYSTEM FREQUENCY

#H communication 66"69E H, with K7; channels with 7:

CH spacing.

H communication 7"7: HA*8*= 6@;"6K:; CH, with spacing ;.: CH,

channeling time less than Dsec.

#+R 6;"66 H, with 6E; channels, :; CH

spacing, channeling time less than E;ms.

+!A ultiple'ed signals of 6;.7, 66.99 and 69.E

CH transmitted omnidirectional from eight

stations located strategically around the

world.

*! Airborne interrogator0 6;7:"66:; H

Transponder0 @E7"6769 HAT4 Transponder 4enter fre-. of 6;9; H

"9d= points at


19/41

INTERFERENCE

The electromagnetic environment of an ac radio system is such that it may

suffer from interfering signals andor noise, man"made or natural, and causeinterference itself to other systems.

Interference may be either radiated or conducted.

As the ac flies through the atmosphere, it pics up electrical charge due to

frictional contact with the atmospheric particles / also while flying through

cloud formations, within which a very strong electric fields e'ist


20/41

Methods of reducing interference:

1. Isolation:

This is the easiest and most practical method of radio noise suppression.

This involves separating the source of radio noise from the ip circuit of the

affected e-uipment.

2. 8on,n:

*uring flight the electric charge develops on the surface of the aircraft in

two ways0

P+e-,*,t(t,on6 6t(t,- ,6-0(+e:

This is developed, as the ac moves through the air / due to

friction with other particles such as snow, rain, ice, dust etc. As

the flow moves over the surface the negative charges are left

behind and positive charges are discharged into the atmosphere.

C0(+e 4e to ee-t+o6t(t,- ,n4-t,on:

This occurs when the ac moves through the electric field,

generally created due to the cloud formation. Thus develops

high voltage on the certain parts of ac.

The static or electrostatic discharge may cause haardous effect due to difference

in potential between the parts of ac. thus the communication lin consisting of low

resistance lin between the parts of ac must be established which will,

1imit the potential difference between various parts of ac.

!liminate the static discharge / reduces any fire riss.

Removes the e'ceptionally high voltage and current from the body of ac

into the atmosphere from the e'tremities of ac.

Reduces interference between the radio and navigational aids.


21/41

T0,6 656te) ,6 -(e (6 8on,n S56te).

The continuous lin is formed by metal strip conductors 3oining fi'ed metal

parts e.g. pipelines 3oined together to either side of non"metallic coupling /

by short lengths fle'ible conductors for 3oining various moving parts e.g.flight control surfaces / components mounted on fle'ible mountings etc.

8on,n ,6 o/ tBo t5*e6:

P+,)(+5 8on,n:

Primary electrical bonding is used between ma3or components, engines,

e'haust surfaces e.g. light control surfaces and the main structure of earth.

Se-on(+5 8on,n:

N$econdary electrical bonding is used between components and earth for

which primary conductors are not specifically re-uired e.g. pipelines

carrying flammable fluids, metal conduits, 3unction bo'es, door plates etc.

3. S-+een,n:

$creening performs similar function to bonding in that it provides a low

resistance path for voltages producing unwanted radio fre-uency

interference. The voltage to be conducted by a screening system are those

stray ones due to the coupling of e'ternal fields originating from certain

items of electrical e-uipment, / circuits when in operation.

!.g. *4 generators, engine ignition system, *4 motors, time"switches, and

similar apparatus designed for maing and breaing circuits at a controlled

rate.


22/41

In e-uipment such as generator, motors and time switches several

capacitors, which provide a low resistance path are interconnected

across the interference sources i.e. brushes, commutators, / contacts

to form a self"contained unit nown as $5PPR!$$+R.

or cables of ignition systems, the cables are enclosed in a metal

braided sheath.

The suppressor and the metal screens are connected to the main earth or ground

system of an aircraft.

4. S0,e,n:

$hielding is one of the most effective methods of suppressing the radio

noise. T0e *+,)(+5 o'e-t,@e o/ 60,e,n ,6 to ee-t+,-(5 -ont(,n t0e

+(,o /+e>4en-5 no,6e ene+5.

In practical applications, the noise energy is ept flowing along the inner

surface of the shield to ground instead of radiating into space.

The use of shielding is particularly effective in situations where filters can?t

be used.Ignition using spar plugs are usually shielded to minimie radio

interference.

5. P+o*e+ !+o4n,n:

It is essential whenever dealing with very low signal levels.

There should be separate ground wire runs for signal returns, signal shieldreturns, power system returns and case or chassis ground.

These ground wire runs must be tied together at a single reference point to

point ground loops.


23/41

6. C,+-4,t De6,n:

$ome of the suggested circuit design to reduce interference is0

5se of differential amplifiers for common mode

cancellation.

5se of instead of A wherever possible.

5se of !T instead of bipolar devices.

$ignal cables should be routed as deeply as possible in

cable channels.


24/41

SOLDERIN! TECHNIQUE

$oldering is a process in which two or more metal items are 3oined together

by melting / flowing a filler metal into the 3oint, the filler metal has

relatively low melting point.

In a soldering process, heat is applied to the parts to be 3oined, causing the

solder to melt and be drawn into the 3oint by -(*,(+5 (-t,onand to bond to

the materials to be 3oined by Bett,n (-t,on.

After the metal cools, the resulting 3oints are not as strong as the base metal,

but have ade-uately strength, electrical conductivity, / water tightness for

many uses.

Applications are assembling electronic components to printed ct.board, in

plumbing system.

T5*e6:

1. So/t Soe+,n: at D;; degree 4O generally0 silver, aluminum,

copper etc.

2. H(+ Soe+,n: at e'cess of D@; 4O silver is used.

3. In4-t,on Soe+,n: high fre-. A4 currentO copper coils are used.

Te-0n,>4e6:

1. Re/oB o+ ;(@e Soe+e:

Reflow soldering is a process in which a solder paste is used to stic the

components to either attachment pads, after which the assembly is heated

by an infrared lamp, or by passing it through a carefully"controlled oven,

or soldering with a hot air pencil.

2. H(n Soe+e:

or hand soldering of electronic components, the heat source tool should

be selected to provide ade-uate heat for the sie of 3oint to be completed.


25/41

MICRO;A%E DE%ICES

icrowave devices are those devices which deal with the transmission of

signal of fre-uency higher than H.

At higher fre-uency, the noise level / power handled increases.

Thus these devices helps to limit the noise level and power handled while

dealing with the higher fre-uencies.

There are different types of icrowave devices, they are listed and

e'plained in short, below0

6. ;(@e4,e6:

2. D,+e-t,on( Co4*e+6:

3. I6o(to+6:

. C,+-4(to+6:

". Po,nt&-ont(-t D,oe:

$. 8((n-e D4*exe+:

. 8((n-e M,xe+:

. T+(@e,n ;(@e t4'e


26/41

SATELLITE COMMUNICATION


27/41

A**,-(t,on6 ,n (,+-+(/t:

1. $atellite radio0 It offers audio services.

2. lobal Positioning $ystem (P$).

3. round Pro'imity %arning $ervice (P%$).

. %eather orecasting.

". 5sed for civil and military communication applications.

$. Telephone.


28/41

COCKPIT %OICE RECORDER

All multi"engine turbine"powered aircraft with a ma'imum tae"off weight

in e'cess of :K;; g and with seating for more than nine passengers shall bee-uipped with a cocpit voice recorder.

The voice recorder must be capable of retaining recorded information over

the period of the last 7 hours of operation and the parameters recorded must

be as follows0

All radio voice communications received or transmitted from the flight dec.

All sounds within the flight dec environment, including audio signals

received by each boom and mas microphone in use.

#oice communications between flight crew members on the interphone

systems. All voice or audio signals identifying navigation or approach aids, as

received on crew headphones or speaers.

All announcements made by the flight crew on the public address system.

or aircraft with a ma'imum tae"off weight of less than :K;; g the

recording time may be limited to 9; minutes.

The cocpit voice recorder must automatically begin recording before the

aircraft first moves under its own power and continue until it is no longercapable of moving under its own power. In practical terms, this is usually

from first engine start to last engine shut"down.

The voice recorder container must be easy to locate in a crash situation by

painting it a distinctive orange or yellow color with reflective material

attached.

It must also include an automatically activated underwater detection device

and it must be resistant to shoc, heat and fire.

The recorder must be installed in a location where its recordings are least

liely to suffer damage.

The site chosen is usually as far aft as practicable, typically close to the rear

pressure bulhead.


29/41

It must receive its electrical power from a bus bar that can be relied upon to

continue providing power under all circumstances and that is separate from

the aircraft&s essential and emergency services.

There must be a means of preflight checing the cocpit voice recorder forserviceability. An aircraft may only be dispatched with an unserviceable

recorder provided that the means of repairing it are not available and that the

aircraft does not complete more than eight subse-uent consecutive flights

with the device unserviceable.


30/41

T+(n6),tte+ Co)',ne+ J Re-e,@e+ M4t,&-o4*e+6

T+(n6),tte+ -o)',ne+plays a ey role in present wireless communication

systems as they combine signals from various radios / feed the combined

signal to one single antenna.

It also provides necessary isolation between transmitters which decreases

any modulation interference.

There are three types of transmitter combiners that are widely used, based on

end applications0

1. Re)oteA4to t4ne -(@,t5:

This type of combiners is very attractive because of their low insertionloss.

2. C(@,t5 Fe++,te:

This type of combiner is similar to the auto tuned type, e'cept that

they lac the microprocessor.

3. H5'+, Fe++,te:

This type of combiners is preferred in system that re-uires channel

spacing in the order of 9; CH.

The main function of Re-e,@e+ M4t,-o4*e+6 is to connect the severalreceivers to a single antenna while maintaining signal integrity.

These are essentially of two types0

1. A-t,@e M4t,-o4*e+6:

Active multicouplers have built in low noise amplifiers to overcome

signal loss due to divider circuit and pre"selector filters.

These are more popular in UHF%HFbase station applications.

2. P(66,@e M4t,-o4*e+6:

Passive multicouplers do not have such amplifiers and therefore the

signal loss is comparatively higher than active ones. This increases thetotal 8oise igure of the system and maes them unstable in certain

base station applications.

These are preferred in HFbroadcasting stations, so that their inherent

loss provides re-uired attenuation to prevent receivers from going into

saturation.


31/41

8OOST J TRICKLE CHAR!IN! OF 8ATTERIES

8oo6t -0(+,ninvolves short periodic overcharging, which releases

gas and mi'es the electrolyte, thus preventing stratification of the

electrolyte in the battery. In addition it also assists in eeping all batteries at the same capacity.

*uring boost charging, the prescribed time limit of charging should

not be e'ceeded otherwise '4+n o4t+5 o4t of battery may occur.

=oost charging should be done using a regulated constant voltage

charger by setting the charger voltage to 7.3&2. %Ce.

%hile in storage the ac batteries should be boost charged every @;

days or when the open circuit voltage drops below 2.7 %Ce.

T+,-e -0(+,n o+ /o(t -0(+,n means charging a battery at a

similar rate as its self"discharging rate, thus maintaining full capacity

of battery.

*uring tricle charging the charging rate should not be greater than

the level of self"discharging or overcharging.

Tricle charging will wor to eep the battery charged if used once a

month or so for a day.

NOTE:

The difference between tricle and float charging is that float charger

has a circuitry to prevent overcharging whereas tricle charger will

eep on charging no matter whether the battery is fully charged or not.

$o it needs to be connected and disconnected continuously.

SPECTRUM ANALYSER


32/41

The modern spectrum analyer basically consists of narrow band

super"heterodyne receiver / a 4R+.

The circuit incorporates a saw"tooth generator, above which supplies a

ramp vtg. to the fre-uency control element of the vtg. tuned local

oscillator.

The local oscillator then swept through its fre-uency band.at a linear

rate.

The saw"tooth vtg. is simultaneously applied to the horiontal plates

of the 4R+.

The R.. signal to be tested is applied to the ip of mi'er stage.

The saw"tooth generator maes the local oscillator sweep through its

fre-uency band to beat with the ip signal to produce the desired

intermediate fre-uency.

An I.. component is produced only when the corresponding

component is present in the R.. ip signal.

The resulting I.. signals are amplified and then detected.

After that they are applied to the vertical deflection plates of the 4R+,

thereby producing a display of amplitudes vs. fre-uency on the screen.

S,n( to No,6e R(t,o


33/41

It is defined as the ratio of signal power to the noise power corrupting

the signal.

A ratio higher than F6G indicates more signal than noise.

$8R P (signal)P (noise)

%here P is average power.

SINAD:

$I8A* stands for signal"to"noise and distortion.

It is a measure of the -uality of an audio signal from a common

device.

$I8A* P (signal) < P (noise) < P (distortion)

P (noise) < P (distortion)

SN SNR SINAD

6. It is the ratio of signal to noise

power.

It is the ratio of signal to noise plus

distortion power.

7. ay be Q 6. 8ever Q6

9. 5sed to measure howmuch

signal is corupted due to noise.

5sed to measure -uality of audio

signal.

MAKIN! SINAD MEASUREMENT

To mae the $I8A* measurement a signal modulated with an audio tone is

entered into the radio receiver. A fre-uency of 6 CH is taen as the

standard.

A measurement of the whole signal (i.e. signal


34/41

As the fre-uency of the tone is nown, the regenerated audio passed through

a notch filter to remove the tone.

The remaining noise and distortion is then measured in audio level meter.

After obtaining the figures for the signal< noise


35/41

$8 !CA ILS

1. It uses high precision radar

system.

It uses high precision instrument

system.

2. Radar system is used to bring

the ac into the approach one

and guide it along the correct

path of descent to a point very

#arious instrument systems are

used to guide the ac.


36/41

near to the runway.

3. It comprises two radar0

a) $urveillance Radar

!lement ($R!).

b) Precision Approach

Radar (PAR).

It uses three instruments0

a) 1ocalier

b) lide $lope

c) arer =eacons

. $imple and cheap. 4omplicated and costly.

". Accuracy depends on human

guidance.

Accuracy depends on Instrument.

$. Human error can be there. 8o chance of human error.. 1ow range. %ide range.

SN ATC T+(n6*one+ DME

1. Transponder replies to the

valid interrogation only.

Transponder replies to all

interrogation.

2 Reply have pulse of R..

6;@;H with spacing 7;.9

sec.

Reply have pulse of R.. @E7"

6769 H with spacing 67sec.

3. 67 coded pulses are spaced. 9;;; pulsesec.


37/41

. 8oise effect is more. 8oise effect is less.

". 1ow gain. High gain.

HoB R.F. -('e o66 -(n 'e )e(64+e '5 46,n %S;R )ete+ to (66e66 ,t6

6e+@,-e(',,t5 J 6(t,6/(-to+5 o*e+(t,on.

It is important to now that for accurate #$%R measurement of devices, the

#$%R should be measured at the input of the device in -uestion.

Any cable loss or attenuation will mae the #$%R at the ip of the cable

appear much better than at the load or termination.

The reason is that the cable loss or attenuation increases the return loss.


38/41

or e.g. let?s say that there is 9d= of attenuation along the length of a cable. If

we send 6;;% forward power into the cable, only :;% maes it to termination.

1et?s say that the termination reflects 9;% bac. %hen the reflected signal

maes it bac to the amp., the same 9d= of cable loss will reduce the reflected

power to 6:%. The amp.would see a #$%R of 7.7E.

However, using :;% forward power and 9;% reverse power to calculated

#$%R, we end up with a #$%R of K.@. The amp. sees a return loss of .7 d=

but at the termination the return loss is 7.7 d=, or e'actly Ed= difference.

4able with 9d=

loss

HoB %S;R ,6 )e(64+e ,n ( t5*,-( +o4n ,n6t((t,on. I6 t0e %S;R 6()e ,/

)e(64+e (t t0e t+(n6),tte+ en o+ (t t0e (ntenn( en (n ,/ not ex*(,n.

%hile using meters that use voltage or current as their measurement

parameters, then they give correct readings only when the load is not tooreactive i.e. the $%R being measured is low.

The meters must also be connected to tae reading at the load feed point or

at half wavelength distances along the transmission line, bac from the load.


39/41

This usually means that the transmission line needs to have a length which is

an integral value of its electrical length.

The electrical length for half wavelength and -uarter wavelength

transmission line is respectively given by

! 6:; (f) ! K: (f)

%here,

#elocity factor

f fre-uency of antenna.

$%R meters based on power measurements gives results which are

independent of length.

A true R.. wattmeter is used fitted with a directional coupler so as to

measure the forward and reflected power separately.

#$%R

A simple #$%R meter is shown below.

RESISTOR COLOR CODES

The resistance value of each resistor can be measured by using ohmmeter,

but this is seldom used, as most of the wire wound resistors have their

resistance values in ohms )(+e on t0e 'o5 o/ t0e +e6,6to+.


40/41

any carbon wound resistance are similarly mared but due to heat, these

marings decolories, maing it difficult to read and moreover the carbon

wound resistances are too small to visualie these marings.

Thus, the color codes system is used to indicate the resistance value where

each color corresponds to particular value. There is only one color code system, but these color codes can be

represented in two ways.

1. 8o5 en ot 656te)

2. En to -ente+ 656te)

In each color code system only three colors are used to indicate resistance

value and fourth color indicate the tolerance limit. =y reading the color

codes properly the resistance value can be determined.

There may be


41/41

!REAT & green

8RITAIN &blue

HAS

%ERY & voilet

!OOD & gray

;IFE & white

;EARIN!

!OLDEN & gold

SIL%ER & silver

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