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RNAV > BASIC RADIO DAY 1 > Flashcards

BASIC RADIO DAY 1 Flashcards

1
Q
A

C= LAMBDA/FREQUENCY

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2
Q

DOPPLER PRINCIPLE

A

CONVERGING: received frequency increses
DRIVING : received frequency decreases

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3
Q

In phase angle

A

Difference is 0 and the amplitutde adds up

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4
Q
A

VLF 3-300 KHZ
LF 30-300
MF 300-3000

HF 3-30MHZ

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5
Q

MODULATION

A

Process of impressing and transporting information by radio

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6
Q

Pulse modul

A
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7
Q

Amplitude

A

You keep the freequency same,amplitutde changes

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8
Q

Frequency

A

Keep same amplitutde changes the frequency

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9
Q

Phase modulation

A

Phase is flipped ,but the frequency and amplitude changes

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10
Q

Pulse modulation

A

Power contianed within a single pulse

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11
Q

Ampkitude modulation

A

The info is impresses onto the carried wave by altering the amplitude pf the carrier

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12
Q

Frequncy modulation

A

Altering the freqeuncy of the carrier

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13
Q

Am modulation

A

Is susceptible to noise ,because it cant filter the noise

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14
Q

Frequency modulation

A

Amplitude says the same.
Less susceptible to noise
More effiecient ,less power

Noise in genral changes the amplitude and the frequency,thats why fm can detect noise,bc if ampitude changes it ignores bc amlitude should say the say in FM

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15
Q

Phase modulation

A

Used in GPS
Requires comples demmodulator
Reverse phase of carrier

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16
Q

Sidebands

A

When wave is modulated ,the result consists of the carrier frequency plus upper and lower sidebands
All modulations produce sidebands

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17
Q

~signals with two sidebands plus the carrier ,occupy a large bandwith
~removing one sideband increses efficiency
~HF and volmet use single sideband transmission

A

You can remove the carrier o r one of the side bands to make the signal more efficint

18
Q

SCW (suppressed carrier wave)

A

We can suppreses the carrier wave as well making it even more effiecnt.

If ypu take awa ythe carrier the ssignal is not good,so we need to add the carrier at the reciever,this requires a beat requncy oscillator (BFO) at the reciever to re insert the removed carrier wave frequcny

19
Q

Signal classification

A

~first letter: type of modulation of the carrier wave
~second: nature of thrsignal carrier
~third: type of info being transmitted

N0N: carrier wihtout modualtion ,used by NDBs
A1A:carrier with key modulation

20
Q

Antenna

A

Is an elcetric device which converts electric pwer into radio waves and vicevers
Ac current

21
Q

Electromagnetic waves

A

~oscillating electric field (E)
~oscillating magentic (H) field
~perpendicular to each other
~in phase with each other
~

22
Q

Polar diagrapms

A
23
Q

Polarisation

A

~describes the plane of oscillation of the electric component of wave with Regard to its direction of propagation
~determined by the orientation of the antenna

~linear ,vertical or horiznatal

~circular &raquo_space;>requires helical antenna
~elliptical&raquo_space;> requires helical antenna

~receivers antenna must be aligned same way as the transmitter to properly receive the transmitted signal

24
Q

Dipole antenna

A

~simples type of antenna
~wire of length equal to 1/2 wavelentgh
~omnidirectional
~prodices a cone of confusion overhead

25
Q

Loop antenna

A

~good at direction finsding (directional )
~used in ADF equip
~looks for the null postions
~required a second sense antenna to elimiate one of the nulls

Looks for differential voltage untill is 0

26
Q

Paqrabolic antenna

A

~good at amplifying weak signals
‘~used in older weather radar
~highly direcrtional

27
Q

Sloteed planar array antenna

A

~used in moder weather radr
~highle directrional
~sereis of slots which are scanned electronically
~more eff. Than a parabolic antenna.drastically reduces side lobes concentrtating energy into the main beam

28
Q

Helical antenna

A

Two types
~omnidirectional ,normal mode ,VHF adn COMMS
~directional ,axial mode ,GPS

Produces a circular /elliptical plane of polarsation

29
Q

Antenna shadowiin

A

Is always refeared to a/c parts
Ex. While in a turn it could shadow the antenna

30
Q

Reflection

A

An abrupt change in direciton of wave when it hits a surface.
Caused by terrain ,builidng ,other a/c ,water droptlets

31
Q

Refraction

A

A change in direction of wave caused by change in progagation speed when moving from one medium to another

32
Q

Diffraction

A

Bending of waves around objects or through apertures.
Describes the tendency of some waves to follow eartg curvature

33
Q

Factors affecting propagation

A

~absorption: the transfer of waves energy to the matter it has encoutered
~attenuation:gradual loss of energy a wave propartagtion through a medium
~multi path propagattion: wehn one signal with a single point and the time of transmission is refelcetd from surfaces between the transmittter and receiver

34
Q

Superpositon

A

Combination of two or more similar waves

35
Q

Interfernce

A

The result of superpostion of two waves

36
Q

Fading

A

Interference of singal rsulting in changes in signal strength and polarisation .caused by multi path ,weather

37
Q

Static interfence

A

Lectricl discharge,thunderstoms
Man made vhf

38
Q

Wave propagation

A

~space wave,anything is higher than VHF

HF
~ground waves ,trvels along the surface of the earth
~sky waves, refrected by the layers of theionoesphere( VLF,LF,MF,HF)

MF ,possibile sky wave at night

39
Q

Ionosphere

A

Radio waves passing through inosphere layers are attenuated
~lower frequencies expereinces less attenuation

40
Q

Critacl angle

A

Is the first sky waves that returns back

41
Q

Dead space

A

Distance betweeen the limit of the sufaec wa

RNAV (8 decks)

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