Phase1 Seminar

8/10/2019 Phase1 Seminar

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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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Documents

Phase1 Seminar