Upload
jc-garcia
View
245
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Wireless Communication
Citation preview
OPERATION OF RADAR“RADIO DETECTION AND
RANGING”
BASIC DESIGN OF A RADAR SYSTEM
PULSE DOPPLER RADAR
DOPPLER EFFECT
BASIC DESIGN OF A RADAR SYSTEM
FIGURES TRANSMITTER
DUPLEXER
RECEIVER RADAR ANTENNA
INDICATOR
TRANSMITTER PRODUCES THE SHORT DURATION HIGH POWER RF PULSES OF ENERGY THAT ARE INTO SPACE BY THE ANTENNA.
DUPLEXER ALTERNATELY SWITCHES THE ANTENNA BET. THE TRANSMITTER AND RECEIVER SO THAT ONLY ONE ANTENNA IS TO BE USED.
IT PRESENT TO THE OBSERVER A CONTINUOUS , EASILY UNDERSTAND, GRAPHIC PICTURE OF THE RELATIVE POSITION OF RADAR TARGETS.
IT AMPLIFY AND DEMODULATE THE RECEIVED RF-SIGNALS.
IT TRANSFERS THE ENERGY TO SIGNALS IN SPACE WITH THE REQUIRED DISTRIBUTION AND EFFICIENCY.
PULSE DOPPLER RADAR
-PULSE DOPPLER IS BASED ON DOPPLER PHENOMENON.
WHAT IS A PULSE DOPPLER?
“DOPPLER EFFECT”-DOPPLER EFFECT IS THE CHANGE IN
FREQUENCY OF A WAVE CAUSED BY RELATIVE MOTION BETWEEN THE SOURCE OF THE WAVE AND THE OBSERVER.
DOPPLER RADAR MAKES USE OF DOPPLER EFFECT TO PRODUCE VELOCITY DATA ABOUT THE OBJECT AT A DISTANT.
IT DOES THIS BY BEAMING A MICROWAVE SYSTEM SIGNAL TOWARDS A DESIRED TARGET AND LISTENING ITS REFLECTION AND THEN ANALYZING HOW THE FREQUENCY OF THE RETURNED SIGNAL HAS BEEN ALTERED BY THE OBJECTS MOTION.
“OPERATION OF A DOPPLER RADAR”PULSE DOPPLER SIGNAL PROCESSINGFIRST. ENVIRONMENTFirstly the antenna transmit the dozens of pulses. Energy from each transmit pulse propagates in space until some of them bounce back by the reflector.
THREE TYPES OF TRANSMITTERS USED COMMONLY IN WEATHER RADARS:
APPLICATIONS OF A DOPPLER EFFECT
CONTINUOUS WAVE RADAR
• A T Y P E O F R A D A R S Y S T E M W H E R E A K N O W N S TA B L E F R E Q U E N C Y C O N T I N O U S W AV E R A D I O E N E R G Y I S T R A N S M I T T E D A N D T H E N R E C E I V E D F R O M A N Y R E F L E C T I N G O B J E C T S .
• C O N T I N U O U S - W A V E ( C W ) R A D A R U S E S D O P P L E R , W H I C H R E N D E R S T H E R A D A R I M M U N E T O I N T E R F E R E N C E F R O M L A R G E S TAT I O N A R Y O B J E C T S A N D S L O W M O V I N G C L U T T E R .
DOPPLER FREQUENCY SHIFTS
CONTINUOUS WAVE RADAR COMPONENTS
Discriminator AMP Mixer
CW RFOscillator
Indicator
OUT
IN
Transmitter Antenna
Antenna
BLOCK
DIAGRAM
RADAR WAVE MODULATIONAM P L I T UDE M O DUL AT I O N
–Vary the amplitude of the carrier sine waveF RE Q UE NCY M O DU L AT IO N
–Vary the frequency of the carrier sine waveP UL SE - AM P L I T UD E M O DUL AT I O N
–Vary the amplitude of the pulsesP UL SE - F RE Q UE NCY M O DU L AT I O N
–Vary the Frequency at which the pulses occur