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Ppt fundamentalsof radar (1)
- 1. See discussions, stats,and author profiles for this publication at: https://www.researchgate.net/publication/309771431 PPT Fundamentals of Radar Data · November 2016 CITATIONS 0 READS 1,024 1 author: Some of the authors of this publication are also working on these related projects: VLSI Testing View project Opto Deportation View project Naveenbalaji Gowthaman University of KwaZulu-Natal 103 PUBLICATIONS 177 CITATIONS SEE PROFILE All content following this page was uploaded by Naveenbalaji Gowthaman on 09 November 2016. The user has requested enhancement of the downloaded file.
- 2. Fundamentals of Radar SNSCollege of technology (Autonomous) Coimbatore
- 3. RADAR • RADAR –RAdio Detection and RAnging • First successfully demonstrated in 1936 • Electromagnetic Waves are used • Wide range of applications Aircrafts Ship Satellite Communication Communication Systems 2
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- 5. 4 Types of Radar MTI– Moving Target Indicator
- 6. Radar System ofShip
- 7. Terms in RadarSystem Know the following terms: Pulse width Pulse repetition frequency Carrier frequency Peak power Average power Duty cycle 6
- 8. Basic Radar Types •Pulse Transmission • Continuous Wave 7
- 9. Pulse Transmission • PulseWidth (PW) – Length or duration of a given pulse • Pulse Repetition Frequency (PRF) – Frequency at which consecutive pulse are transmitted • Pulse Repetition Time (PRT=1/PRF) – Time from beginning of one pulse to the next – Inverse of PRF • PW determines radar’s – Minimum detection range – Maximum detection range • PRF determines radar’s – Maximum detection range 8
- 10. Pulse Radar Components SynchronizerTransmitter Display Unit Receiver Power Supply ANT. Duplexer Antenna Control 10
- 11. Continuous Wave Radar 11 Continual energy transmission Separate transmit/receive antennas Relies on “DOPPLER SHIFT”
- 12. Doppler Frequency Shifts MotionAway: Echo Frequency Decreases Motion Towards: Echo Frequency Increases RADAR 12
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- 14. Continuous Wave Radar Components DiscriminatorAMP Mixer CW RF Oscillator Indicator OUT IN Transmitter Antenna Antenna 14
- 15. Pulse Vs. ContinuousWave Pulse Echo • Single antenna • Gives range, usually altitude as well • Susceptible to jamming • Range determined by PW and PRF Continuous Wave • Requires 2 antennae • Range or Altitude info • High SNR • More difficult to jam but easily deceived • Can be tuned to look for frequencies 15
- 16. RADAR Wave Modulation Amplitude Modulation – Vary the amplitude of the carrier sine wave Frequency Modulation – Vary the frequency of the carrier sine wave Pulse-Amplitude Modulation – Vary the amplitude of the pulses Pulse-Frequency Modulation – Vary the Frequency at which the pulses occur 16
- 17. Antenna • Two basicpurposes: – Radiates RF energy – Provides beam forming and energy focusing • Must be 1/2 the wave length for maximum wave length employed • Wide beam pattern for search • Narrow beam pattern for tracking 17
- 18. Beam width Vs.Accuracy B ea m w id th v s A ccu ra cy S h ip A S h ip B 18
- 19. Determining Azimuth Angular Measurement Azim u th A n g u la r M ea su rem en t R elativ e B earin g = A n g le fro m sh ip ’s h ead in g . T ru e B earin g = S h ip ’s H ead in g + R elativ e B earin g N S h ip ’s H ead in g A n g le T a rg e t A n g le 19
- 20. Determining Altitude D etermin in g A ltitu d e S lant R ange A ltitu d e A n g le o f E le v atio n A ltitu d e = slan t ran g e x sin 0 elev atio n 20
- 21. 21 Normal radar functions: 1.Range (from pulse delay) 2. Velocity (from Doppler frequency shift) 3. Angular direction (from antenna pointing) Signature analysis and inverse scattering: 4. Target size (from magnitude of return) 5. Target shape and components (return as a function of direction) 6. Moving parts (modulation of the return) 7. Material composition Applications
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