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Chapter 5: Radar Technology, AMIRUL HAKIMI BIN JAMIL A17SC0284 - Coggle…
Chapter 5: Radar Technology
Radar
detect & study far off targets transmitting radio pulses in direction of target then observe reflection of the wave (radio echo concept)
create EM pulse that focuses by antenna and then transmits through atmosphere
objects in path of transmitted EM pulse (target/echo) will scattered most of it but some reflected back to radar
receiving antenna gathers back scattered radiation and feeds it to receiver
beams can be attenuated, reflected and bent by environment
Radar observes what?
target size (cross-section)
target speed (doppler)
target angle (azimuth&elevation) [altitude=slant rangexsin theta]
target features (imaging)
target range, d=c x t/2
Pulse transmission
pulse width (PW): length/duration of given pulse can determine
-radar's min. detection range
-radar's max. detection range
-radar's min. range resolution
pulse repetition time (PRT): 1/PRFrequency (PRF can find max. det. range)
PRT: time from beginning of first pulse to beginning of next pulse.
PRF: freq. at which consecutive pulses are transmitted
Continuous wave radar
employs continual radar transmission
separate transmit & receive antennas
relies on Doppler shift
factors affected radar performance
signal reception
receiver bandwidth
pulse shape
carrier frequency
signal-to-noise ratio
pulse compression
receiver sensitivity
radar receiver performance factors
signal reception
receiver sensitivity
receiver bandwidth
signal-to-noise ratio
pulse effects on radar's performance
pulse shape
pulse compression
pulse power
pulse width
antenna
radiate RF energy & provides beam forming & focus
1/2 of wavelength for max. wavelength employed
wide beam pattern for search analysis to narrow tracking
Reflector shape
orange peel para: used cont. wave, used for fire control
parab. cylinder: for long range app., pulse wave
paraboloid: fire control where can be continuous/pulse wave
working principle
transmitter emits radio waves (radar signal) in predetermined directions
signals reflect to many directions as they contact with any objects
slightly equivalent change in freq.
receiver receives reflected signals which be strengthened by electronic amplifier & signal processing methods
military
target detection/tracking, weapon control
tracks target, direct weapon to intercept & assess effectiveness of engagement
area, ground, air surveillance
air traffic control
ground vehicular traffic & aircraft tracking
mapping of regions & rain in vicinity of airports/weather
safety control for air traffic in vicinity of airports/enroute
advantage
stationary/moving mode
flexible (used in no. of ways)
waves does not require a medium, used in space/air
beam spread can incorporate in many targets
can often select fastest target/best reflection
limitations
radar has wide beam spread (50 ft diameter over 200ft range)
time radar take up to 2 sec to lock target
more interference sources
AMIRUL HAKIMI BIN JAMIL A17SC0284