Radar- Factors Affecting Coverage Flashcards
Radar systems need to be able to….
Identify the range and azimuth of each aircraft within its range coverage.
The accuracy in which a radar system is able to identify range and azimuth of each target within its range is known as…
Resolution of radar
List the 7 factors that determine Radar coverage
1) Aerial Size/Shape/height above ground
2) size of target (PSR)
3) Atmospheric conditions
4) Transmitter Power
5) Receiver Efficiency
6) Pulse Recurrence Frequency (PRF; PSR only)
7) Pulse Length (PSR only)
What is the usual requirement for aerials in ATC?
A narrow azimuth beam combined with a wide beam in eleveation
What is the usual beam width?
2-3 degrees
Note at 60nm would give coverage of 2-3m
If a narrow beam is required then the aerial dimensions must be?
Large
The height of the aerial above the ground must be considered with reference to?
The wavelength
For a given aerial height the shorter the wave length the…
More gaps in high coverage but better will be the low coverage
For a given aerial height, the longer the wave length the….
Fewer gaps in high coverage but low coverage will be poor.
Radars use the “cosecant squared” radiation pattern to avoid wasting energy.
True or False?
True
What information will a vertical coverage diagram display?
The theoretical coverage of display?
What 3 things does the vertical coverage diagram take into account?
1) General Design Factors
2) Environment Conditions
3) Atmospheric Conditions
What does the Unit Coverage Diagram (UCD) show?
Shows actual coverage of radar system after it has been installed at a specific location
What does a unit coverage diagram (UCD) take into account?
Local terrain
The shorter the wavelength the greater the atmospheric effects. True or False?
True.
Short range radar uses which wave length?
3-10cm
Long range area radar uses what wave length?
23-50cm
What does Anoprop (Super-refraction) do?
Produces radar echoes below normal coverage and from ranges in excess of this allowed in the design of the radar.
Transmitting power for PSR must be…
Sufficient allowing for attenuation for the radar to detect an echo from an aircraft at maximum range
Transmitting power for SSR must be….
Sufficient allowing for attenuation for interrogation signal to reach an aircraft at maximum range.
What does PRF stand for?
Pulse Recurrence Frequency
The higher the PRF (together with beam width and scanning rate) the more “hits” on a target and the stronger and more recognisable will be the return.
True or False?
True.
PRF must be
Low enough to accommodate the required maximum range.
Pulse length will affect minimum range of a primary radar system. And cannot receive return if Transmitting.
True or False?
True.
A narrow beam equals a large aenal dimensions
True