Radio Principles & Radar (PSR,SSR,AWR) Flashcards
Electric and Magnetic field components of the electromagnetic wave are at what angle to each other?
Right Angles
With regard to Attenuation, the smoother the surface the wave travels over the (higher, less) the attenuation.
What is the correct answer?
Less
Define Cycle
One complete rotation through all of the values of magnitude and direction of the oscillation (one complete wave)
The most suitable frequency range for Sky Waves is?
**MF and HF
(when higher than HF the radio waves pass through the ionosphere and continue into space)**
The transponder reply light on the the control panel will remain solid (stay on) under what conditions?
When TST (test) function is on or when using the IDENT button
Describe the function of the tilt control on a typical airborne weather radar
Tilt control determines the angle between the beam and the horizon, it is manually tilited in flight up or down (adjust the beam in its vertical plane)
Polarisation is the plane in which the ____ component of the radio wave oscillates
**Electrical **component
State the optimum HF frequencies to use by day and night
At night; lower end of the HF around 3MHz (below 10MHz)
At Day; higher end of the HF band around 30MHz
The transponder code for Radio Failure is?
7600
Wavelength and Frequency are **(inversely, directly) **proportional.
What is the correct answer?
**Inversely **Proportional
PSR radar operates in which frequency bands?
UHF and/or SHF
When the transponder is in SBY mode, it (will, will not) respond to interrogation
What is the correct answer?
Will Not
typical airborne weather radar does not detect… (list three)
Clouds
Fog
Wind-shear
Wind
Clear Air Turbulence
Lightning
Mode A only information will be available when (ON, SBY, ALT, TST) is selected on the transponder control panel
What is the correct answer?
ON
Electromagnetic waves/radiation consist of ____ and ____ fields
consist of **Electric **and **Magnetic **fields
A limit of Mode C information is that it provides pressure altitude to the nearest (10ft,100ft,150ft,50ft)
What is the correct answer?
**100ft
(note: it supplies 1013hPa pressure altitude, which is converted to AMSL by ATC displays/equipment if required)**
Typical airborne weather radar operates on what frequency and what band on the electromagnetic spectrum?
Around 9.4GHz and in the X band microwave spectrum
List two disadvantages of AM over FM
**Requires higher power
Vulnerable to interference causing static**
Sky Wave reception is (improved, degraded) at night
What is the correct answer?
**Improved **at night
When ALT mode is selected on the transponder control panel, the transponder is supplying (Mode C, Mode A) information.
What is the correct answer?
Mode C (Mode A + Altitude)
7500 transponder code is used in what event?
Hijack/Unlawful Interference
Where are Radio Waves positioned on the electromagnetic spectrum?
Lowest end of the spectrum (from Radio up to Gamma)
The frequency of the carrier wave and modulated wave are kept constant but the amplitude of the the carrier wave is varied.
This is describing (AM, FM), What is the correct answer?
AM
One limitation of Mode A or C transponders is that only ____ transponder codes are available for use
4096
Describe Direct Waves
Associated with VHF and higher frequencies, they travel in straight lines and do not bend around obstacles or bend in the ionosphere
State the three emergency transponder codes
7500, 7600, 7700
With regard to airborne weather radar, the ANT STAB switch provides what function?
It enables or disables the automatic antenna stabilisation
The (higher, lower) the frequency the greater the abiliity for the waves to follow the surface
What is the correct answer?
Lower
With regard to airborne weather radar, GAIN control is usually set to what mode?
CAL/AUTO
Define Wavelength
The physical distance between one part of a cycle and the identical part of the following cycle
Atmospheric static is stronger in (summer, winter) and also stronger during (day, night)
What combination gives the correct answer?
stronger in Summer and also stronger during Night
If instructed by ATC to sqwak IDENT, you should (press the IDENT button once, hold the button in until advised by ATC)
What is the correct answer?
Press the IDENT button once
SSB Single Side Band can be used with what modulation type?
Amplitude Modulation (AM)
Define Frequency
The number of cycles per second
List two advantages of AM over FM
**Do not require extra frequencies
Receiver is less complex**
Calculate the wavelength in meters of 150MHz
2.0M
What is the advantage of narrow beam use in PSR/Airborne Weather Radar?
**It provides better resolution resulting in greater ability to distinguish objects that are closer together at a far distance
e.g. two clouds close together could be seen as one cloud without the use of narrow beam**
Frequency Modulation is where the ____ remains constant but the ___ is altered
where the Amplitude remains constant but the **Frequency **is altered
Describe Attenuation
Reduction in strength of a signal as the distance from the transmitter is increased
List two advatages of FM over AM
**Less power is required
Static is virtually eliminated by the use of VHF and constant Amplitude**
State the calculation to find Wavelength given Frequency
**Wavelength = 1/Frequency in Hz
(1= 300,000,000 speed of light in m/s)**
Lower frequency waves can follow the curvature of the earth surface, these waves are called?
Surface Waves
State at least two disadvantages of PSR when compared to SSR
**Clutter cause by reflections from precipitation, ground obstacles, building etc
Variation in size and intensity of returns depending on reflectivity of different targets
Heavy rain degrades performance and reflected signals are weak, the satellite may not be sensitive enough
Does not provide aircraft information
Shorter rated range compared to SSR
Larger power requirement and larger size**
Frequency is measured using what unit?
Hertz (Hz)
What is the disadvantage of single side band units?
The units are more complex and therefore more expensive
‘Phase’ can be defined as the particular stage reached in a cycle expressed as ____
What unit is it expressed as?
° Degrees
What is the advantage of SSB
Bandwidth is reduced offering greater range of channels, noise is reduced and clearer signals are produced
Define critical angle in relation to Sky Waves
The smallest angle from vertical that produces a return wave
Surface Waves can follow the curvature of the earth surface by ____, scattering and ____ tilting
by **diffraction, **scattering and wave tilting
The ground distance between transmitter and the first returning Sky Wave is called ____ ____
Skip Distance
The below image shows a typical radio wave, Label B is showing (wavelength, amplitude, frequency) while Label A is showing (wavelength, amplitude, frequency).
Which combination gives the correct answer?
**Label B = Wavelength
Label A = Amplitude**
SSR operates on the principle of?
Interrigating radar causing a transponder equipped aircraft to respond
Frequency will be halved if wavelength is ____
if wavelength is doubled
Describe wave Diffraction and Scattering
Objects on the earth surface large and small diffract and scatter radio waves re-directing a large portion downward following the earth surface
With regard to airborne weather radar, The (wetter, drier) the precipitation the greater the reflectivity
What is the correct answer?
The Wetter the precipitation the greater the reflectivity
Electromagnetic waves/radiation travel through space at the speed of (light, sound)?
What is the correct answer?
Speed of Light (approx 300,000km/sec)
Phase Difference relates to waves having the same (frequency, amplitude) and not necessarily the same (frequency, amplitude)
What combination gives the correct answer?
the same Frequency and not necessarily the same Amplitude
___ cycle(s) per second is 1 Hertz (Hz)
(How many cycle(s) per second is 1 Hertz)
1 cycle per second is 1 Hertz (Hz)
SSR Radar interrogates on ____MHz and the transponder replies on ____MHz which is a difference of 60MHz
SSR Radar interrogates on 1030MHz and the transponder replies on 1090MHz which is a difference of 60MHz
UHF Primary radar uses a wavelength in the range of ____ to ____cm and SHF in the range of ____ to ____cm
**10 to 100cm **and SHF in the range of 1 to 10cm
What is the rule-of-thumb formula for calculating max range of reception of Direct Waves? (assuming transmitter is at sea level)
**Multiply the square root of the aircraft height in feet by 1.25, Giving an answer in nautical miles.
e.g. an aircraft at 32,000ft would give a range of 223.6nm**
The below diagram shows a typical Sky Wave. Label A is showing (skip distance, dead spaces, direct waves) while Label B is showing (skip distance, dead spaces, direct waves)
Which combination gives the correct answer?
**Label A= Skip Distances
Label B= Dead Spaces**
Sky Wave reception improves when the ionosphere layer (increases, decreases) in density at night
What is the correct asnwer?
Decreases
If frequency is doubled, the wavelength will be ____
wavelength will be halved
Regarding radio waves, the max displacement of the oscillation away from the mean value line during a cycle is called?
Amplitude
With regard to airborne weather radar. When switched ON, ANT STAB tilts the antenna in (pitch,roll,yaw) to keep it in the (vertical, horizontal) plane.
Which combination gives the correct answer?
When switched ON, ANT STAB tilts the antenna in roll to keep it in the vertical plane.
The frequency used by airborne weather radar is selected because?
Allows return of significant precipitation and avoid returns from cloud and light precipitation such as drizzle
The main disadvantage of secondary surveillance radar is?
It requires the aircraft to be transponder equipped otherwise it cannot be seen by the radar
What is the main advantage of modern Doppler weather radar over traditional weather radar systems?
Doppler provides speed and direction (velocity) of winds as opposed to reflectivity. e.g. provide potential windshear information
State the rated range of SSR radar in NZ
256nm
What transponder mode should be selected when changing transponder codes as a precautionary measure?
Mode changed to SBY (standby)
Airborne Weather Radar operates on the same principle as (PSR, SSR)
What is the correct answer?
PSR, Using the echo/reflection principle
A transponder operating on Mode Alpha provides ____ and ____
provides position and identity (transponder code)
State the range of PSR Primary radar in NZ
80nm
PSR operates on the principle of ____
Echo
(or Pulse, Reflection)
