phase1 seminar
TRANSCRIPT
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Evaluation of Polyphase Filter
architecture for Pulse detection andmeasurement
JEEVITHA T
1DS12LEC06
EXTERNAL GUIDE: INTERNAL GUIDE:
HEMANT V PARANJAPE KIRAN GUPTA
SCIENTIST D ASSOCIATE PROF
DARE,DRDO ECE DEPT,DSCE
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Introduction
Previousmethods
used
Problem
definition
Pros andcons
conclusion
AGENDA
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1905Russo Japanese war
1914World War 1
1939World War 2
1965-1971Vietnam war
1973The Middle East War
1982Falkland War , Lebanon War
HISTORICAL DEVELOPMENTS IN EW
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One
Electronic Support Measure(ESM)
Two
Electronic Counter Measure(ECM)
Three
Electronic Countercountermeasures(ECCM)
ELECTRONIC WARFARE
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ESM
ACOUSTICDETECTION
SYSTEM
COMMINTERCEPTRECEIVERS
RADARINTERCEPTRECEIVERS
INFRAREDINTERCEPTRECEIVERS
LASERINTERCEPTRECEIVERS
TYPES OF
ESM..
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Wideband EW Rx Narrowband Comm
Rx
1. Wideband pulsed radars
2. Wide input bandwidth
3. Information of the input
signal is unknown.
4. Outputs the Pulse
Descriptor Words(PDW)
1. Communication signals
2. Narrow input bandwidth
3. Information of the input
signal is known.
4. Outputs recover
information.
DIFF B/W COMMUNICATION RX AND
ELECTRONIC WARFARE RX
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EVOLUTION OF EW RX
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Time tag for the leading edge of the
radar pulse in the received signal
To calculate PRI
Used to deinterleave the radar pulse
train
TOA IMPORTANCE
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Deinterleaving
PRIgeneration
Radaridentification
tracking
revisiting
FUNCTIONS OF EW PROCESSOR
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SIGNAL PROCESSING REQ..
1. DFT
Mathematical procedureharmonic/frequency contentdiscrete
signal.
One to one mapping
For N input time domain samplesspectral content at N equally
spaced frequency points
DFT outputsum of point to point product b/w i/p sequence and
complex sinusoid.
Analysis frequencymfs/N
Frequency resolutionfs/N
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FIR filters are linear phase filters, so phasedistortion is avoided1
stable due to their absence of poles in thetransfer function2
feed forward filters, and do not utilize
feedback3
design is primarily performed using thewindowing method4
2. FILTERING
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change in the sampling rate
two basic components of a
multirate system are the
down sampler (or decimator)
and the up sampler (or
expander)
y(n) = x(Mn)
MULTIRATE SYSTEMS
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POLYPHASE FILTERING
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FFT based architecture
Non overlapped FFT architecture
Overlapped FFT architecture
FIR filter based architecture
Cascaded FIR filter basedarchitecture
Mixed architecture
FFT+FIR filter architecture
Polyphase FFT architecture
DIGITAL RECEIVER SIGNAL PROCESSING
ARCHITECTURE
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NON-OVERLAPPED FFT
Input dataframes of N samplesFFT
Poor time resolution
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OVERLAPPED FFT
Input dataoverlappedFFT
Data overlap128/192 (256)
Advantages: increasesoutput rate, time resolution without degrading
frequency resolution.
Disadvantages: implementation complexity
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CASCADED FIR FILTER BASED
ARCHITECTURE
Input bandM wide filters.
Each M filterN narrow filters
Threshold is applied for each filter output.
Good time resolution
Narrow filters usedfilter order increasenumber of
multipliers.
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FFT+FIR FILTER ARCHITECTURE
Detection of FFTfour FIR filters
Parameter measurement4I and 4Q decimated filters.
Better time resolutionsimple FFT.
Requires extra storage.
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PROPOSED METHOD: POLYPHASE FFT
Decimationfrequency domain
Decimation in frequencyreduces complexity of FFT
Determines spectral output of N point FFTN/D point FFT
Trade offfrequency resolution
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Continued..
Channelizationpolyphase filtering
N/D no., of filters with D no., of taps
Produces same output as N point FFT
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One
Incoming N data samplesMbranches
Two
M point FFT is performed
Three
Decimationgaps in frequencytime domain window
DESIGN PROCEDURE
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ADVANTAGES
Good time resolution
Excellent filter shapes
DISADVANTAGES
Poor frequency resolution
ADVANTAGES AND DISADVANTAGES OF
THE PROPOSED METHOD
REFERENCES
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REFERENCES
Approaches towards implementation of multi-bit digital receiver using FFT,
Abhijit S Kulkarni, Vijesh P, Hemant V Paranjape, K Maheswara Reddy. DefenceScience Journal, Vol 63, No.2 , March 2013,pp.198-203, DESIDOC.
Paramaterizable channelized wideband digital receiver for high update rate,
Buxa Peter, Wright state university, 2003(MS Thesis).
DARE Digital Receiver Design Document VER 1.0, DARE 2010.
Electronic Warfare, Mohinder Singh, Institute of Armament technology,
Pune,DESIDOC.
Digital techniques for Wideband digital receivers Ed 2, Tsui James B Y,Norwood, MA: Artech house, 2001.
Lyons, Richard. Understanding digital signal processing. Pearson Education,
2004.
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