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moving target indicator it is a must raed to understand
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MOVING TARGET INDICATOR
( MTI )
MTI - INTRODUCTION
• REQUIREMENT TO ELIMINATE CLUTTER.
• PULSE RADAR (RANGE LIMITATIONS DUE TO PW AND PRF ).
• CONTINUOUS RADAR (LACK OF TIMING MARKS IMPLIES NO RANGE INFORMATION ).
• PULSE DOPPLER RADARS .
PULSE DOPPLER RADARRETURN SIGNAL CHARACTERISTICS
• FIXED OBJECT RETURNS.• MOVING TARGET RETURNS.
( DOPPLER SHIFT BY COMPARISON OF RETURNED SIGNAL WITH TRANSMITTED SIGNAL )
• REQUIREMENT OF COHO. (COHORENT OSCILLATOR)
• COMPARISON OF DOPPLER FREQUENCY GIVES AMPLITUDE VARIATION DUE DIFFERING VALUES OF INCIDENT PHASE OF SIGNALS.
PULSE DOPPLER RADARRETURN SIGNAL CHARACTERISTICS
MTISUCCESSIVE PULSE COMPARISON
• DELAY LINE TECHNIQUE• ANALOGUE MTI
QUARTZ CRYSTALSACOUSTIC DELAY LINES
• DIGITAL MTI COMPUTER TYPE MEMORY SYSTEMSeg. ?
MTI – BLIND SPEEDS
MTI – BLIND SPEEDS
• λ/2 IN PRP=1/ PRF
• SOLUTION – CHANGING PRF
THIS WILL ENSURE DIFFERENCE OF AMPLITUDE IS RE-ESTABLISHED PULSE TO PULSE.
• RESULTS IN AMBIGUITY IN RANGE.
MTI – BLIND SPEEDS
• SOLUTION – CHANGING PRF
THIS WILL ENSURE DIFFERENCE OF AMPLITUDE IS RE-ESTABLISHED PULSE TO PULSE.
• RESULTS IN AMBIGUITY IN RANGE.
AIRBORNE MTI
• USED IN EARLY WARNING RADARS, RECONNAISSANCE RADARS AND AIs.
• SIMILAR PRINCIPLES.• VELOCITY OF TARGETS wrt. EARTH.
( COMPENSATED BY FALSE DOPPLERSHIFT IN REFERENCE SIGNAL TO COMPONENT OF A/C VELOCITY ALONGTHE RADAR BEAM. IN CASE OF SCANNING BEAM COMPENSATION HAS TO BE CONTINUOUSLY CHANGING. )
