ESTIMATING TIME PARAMETERS FOR RADAR PULSE DESCRIPTOR

WORDS USING FPGA

HATEM NABIH JABAS

UNIVERSITI TEKNOLOGI MALAYSIA

ESTIMATING TIME PARAMETERS FOR RADAR PULSE DESCRIPTOR

WORDS USING FPGA

HATEM NABIH JABAS

A project report submitted in partial fulfilment of the

requirements for the award of degree of

Master of Engineering (Electronics and Telecommunication)

Faculty of Electrical Engineering

Universiti Teknologi Malaysia

JUNE 2018

iii

DEDICATION

To my lovely mother, who gave me endless love, trust, constant

encouragement over the years, and for her prayers.

To my family, for their patience, support, love, and for enduring the ups and

downs during the completion of this thesis.

To my cousin, for his special support, trust, engorgement to accomplish this

work and standing beside me in every step.

This work is dedicated to them.

iv

ACKNOWLEDGEMENT

I wish to express my deepest appreciation to all those who helped me, in one

way or another, to complete this project. First and foremost, I thank Allah almighty

who provided me with strength, direction and purpose throughout the project. Special

thanks to my project supervisor Associate Professor Dr. Ahmad Zuri bin Sha’ameri

for his patience, guidance and support during the execution of this project and Dr.

Zulfakar Aspar for his great support and engorgement as well. Through their expert

guidance, I was able to overcome all the obstacles that I encountered in these enduring

ten months of my project. In fact, they always gave me immense hope every time I

consulted with him over problems relating to my project. May Allah reward them

abundantly.

Lastly, I would like to communicate my appreciation to my fellow graduate

students and contemporaries, who have supported me in various traditions may Allah

reward them.

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ABSTRACT

Electronic warfare (EW) system is an important capability that can advance

desired military or, conversely, impede undesired ones. In a military application, EW

provides the means to counter, in all battle phases, hostile actions that involve the

electromagnetic (EM) spectrum. An electronic support (ES) system is used by the

military for intelligence gathering, threat detection, and as a support to electronic

attack system. Its main feature is to determine the Pulse Descriptor Words (PDWs)

which consists of: 1. Frequency. 2. Time of Arrival (TOA). 3. Pulse Width (PW). 4.

Direction of Arrival (DOA). Then, PDW signal will be applied on deinterleaver to

determine Pulse Repetition Interval (PRI) and it could be a simple pulse, staggered or

jittered pulse. The estimated signal parameters are then used as input to a classifier

network to determine the identity of the received signal. This project investigates on

the hardware implementation on FPGA (Field Programmable Gate Array) of the time

parameters of radar signals after the signal is demodulated. A set of test signals

representing different types of radar is first generated which is then used to estimate

pulse word descriptors from the time parameters. Using histogram analysis, the

estimated pulse word descriptors is then classified with a set of known data base. The

performance is evaluated at various signal-to-noise ratio conditions. In this work, 128

clock cycles are used to complete the signal analysing with various values of latency

depending on the PRP type. The design is more efficient in term of FPGA resources

utilization comparing with previous work. The proposed design can be used for the

purpose of auto-measure of time parameters in many EW applications which have

physical limitations in size, weight and power consumption (SWaP) such as in an

aircraft.

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ABSTRAK

Sistem Peperangan Elektronik (EW) adalah sebuah sistem keupayaan penting

yang boleh memajukan tentera yang dikehendaki atau sebaliknya menghalang orang

yang tidak diingini. Dalam aplikasi ketenteraan, peperangan elektronik menyediakan

cara untuk menghalang semua fasa pertempuran, aksi permusuhan yang melibatkan

spektrum elektromagnetik (EM). Sistem sokongan elektronik (ES) digunakan oleh

tentera untuk mengumpul maklumat perisikan, mengesan ancaman dan sebagai

sokongan kepada sistem serangan elektronik. Ciri utamanya adalah untuk menentukan

Pulse Descriptor Words (PDWs) yang terdiri daripada: 1. Kekerapan. 2. Masa ketibaan

(TOA). 3. Lebar denyutan (PW). 4. Arah kedatangan (DOA). Kemudian, signal PDW

akan diaplikasikan ke atas deinterleaver untuk menentukan Pulse Repetition Interval

(PRI) dan ia juga boleh menjadi nadi mudah atau nadi denyutan. Isyarat parameter

yang dianggarkan kemudiannya digunakan sebagai input kepada rangkaian pengelas

untuk menentukan identiti isyarat yang diterima. Projek ini menyiasat pelaksanaan

perkakasan ke atas isyarat radar iaitu masa parameter FPGA (Field Programmable

Gate Array) selepas isyarat demodulasi. Satu set ujian isyarat yang mewakili pelbagai

jenis radar dijana untuk pertama kali yang kemudiannya digunakan untuk

menganggarkan deskriptor kata denyut daripada parameter masa. Dengan

menggunakan analisis histogram, anggaran deskriptor kata denyut kemudiannya

diklasifikasikan dengan satu set pangkalan data yang diketahui. Prestasi ini dinilai

dengan pelbagai keadaan nisbah bunyi-ke-bunyi. Dalam projek ini, 128 kitaran jam

digunakan untuk melengkapkan analisis isyarat dengan pelbagai nilai latensi

bergantung kepada jenis PRP. Reka bentuk ini lebih cekap dari segi penggunaan

sumber FPGA berbanding kerja sebelumnya. Reka bentuk yang dicadangkan boleh

digunakan untuk tujuan pengukuran auto parameter masa dalam kebanyakan aplikasi

EW yang mempunyai batasan fizikal dari segi saiz, berat dan penggunaan kuasa

(SWAP) seperti dalam pesawat.

vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF ABBREVIATIONS xiii

1 INTRODUCTION 1

1.1 Background 1

1.1.1 Definition of Electronic Warfare (EW) 1

1.1.2 ES Receiving System 2

1.2 Problem Statement 3

1.3 Objective 4

1.4 Scope of Work 4

1.5 Research Flow 5

1.6 Summary 6

2 LITERATURE REVIEW 7

2.1 Basic Radar Principle 7

2.2 Radar Warning Receiver 8

2.3 Radar Signal Parameters 11

2.3.1 Frequency Parameters of Radar 11

2.3.2 Timing Parameters of Radar 12

viii

2.3.3 Types of PRI 13

2.4 PRI Estimation Techniques 14

2.5 Real-Time Implementation 15

2.6 Real-Time Processing Technologies 17

2.6.1 Microprocessors 17

2.6.2 General-Purpose Graphical Processing Units (GPUs) 17

2.6.3 Field Programmable Gate Arrays (FPGA) 18

2.7 Summary 18

3 THEORY 19

3.1 Introduction 19

3.2 Algorithm Flow Chart 19

3.2.1 Receive Noisy Signal and Denoising the Signal 21

3.2.1.1 Thresholding 21

3.2.1.2 Neyman-Pearson Theorem 22

3.2.2 PRP Extracting 23

3.2.3 PRP Analysing 24

3.2.4 Emitter Recognition 26

3.3 Data Flow Graph 27

3.3.1 Denoising and PRP Extracting 27

3.3.2 PRP Analysing 28

3.3.3 Extracting PRP Values from the RAM 30

3.3.4 PRP Type Recognition 32

3.4 Summary 32

4 RESULTS AND DISCUSSIONS 33

4.1 Overview 33

4.2 Matlab Simulation 33

4.2.1 Simple PRP 33

4.2.2 2-level Staggered PRP 34

4.2.3 Jitter PRP 35

4.3 Implementation on FPGA Results 36

4.3.1 Top-level Hardware Module 36

ix

4.3.1.1 Thresholding and PRP Extract module 37

4.3.1.2 PRP Analyse Module 37

4.3.1.3 Emitter Recognition Module 38

4.3.2 Compilation Report 38

4.3.3 Hardware Simulation Results 39

4.3.3.1 Simple PRP 39

4.3.3.2 2-level staggered PRP 40

4.3.3.3 Jitter PRP 41

4.4 System Efficiency 42

4.5 Summary 43

5 CONCLUSION AND RECOMMENDATIONS 44

5.1 Conclusion 44

5.2 Recommendations 44

REFERENCES 45

x

LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Specifications of BOW radar warning developed by Saab

Avitronics 9

2.2 Typical pulse width τ 13

2.3 Typical PRI type 14

2.4 Synthesis report 16

4.1 Resources utilization of the design 39

4.2 Efficiency of the designed system 43

xi

LIST OF FIGURES

FIGURE NO. TITLE PAGE

1.1 EW subsystems 2

1.2 Block diagram of an ES receiving system 3

1.3 Project Flow Chart 5

2.1 Basic radar principle 7

2.2 Block diagram of typical RWR 9

2.3 Radar Warning Equipment 10

2.4 Waves and frequency ranges used by radar 11

2.5 A typical radar time line 13

2.6 (a)Simple, (b)Jitter, (c)2_level staggered, (d)3_level

staggered 14

3.1 PRP Estimation Algorithm 20

3.2 ES receiver block diagram. 21

3.3 Probability density functions of AWGN and the signal 22

3.4 PRP extracting block diagram 24

3.5 PRP analysing block diagram 25

3.6 Pattern recognition of the emitter 26

3.7 Thresholding and PRP extracting 28

3.8 PRP analyse 29

3.9 Extracting PRP values from the RAM 31

3.10 PRP type classifier 32

4.1 Simple PRP 34

4.2 2-level staggered PRP 35

4.3 Jitter PRP 36

4.4 Top-level module 36

xii

4.5 Functional block diagram(fbd) of thresholding and PRP

extract module 37

4.6 Functional block diagram (fbd) of PRP analyse module 38

4.7 System output of simple PRP 40

4.8 System output of 2-level staggered PRP 41

4.9 System output of jitter PRP 42

xiii

LIST OF ABBREVIATIONS

ARM - Antiradiation Missile

ART - Adaptive Resonance Theory

AWGN - Additive White Gaussian Noise

COMSEC - Conflict Removal and Communications security

DEW - Direct Energy Weapon

DOA - Direction of Arrival

EA - Electronic Attack

ECM - Electronic Countermeasure

ECCM - Electronic Counter-Countermeasure

ELINT - Electronic Intelligence

EMP - Electromagnetic Pulse

EMCON - Electromagnetic Emissions Control

EMS - Electromagnetic Spectrum

EP - Electronic Protection

ES - Electronic Support

EW - Electronic Warfare

FBD - Functional Block Diagram

FPGA - Field Programmable Gate Arrays

HDL - Hardware Description Language

IP - Instantaneous Power

NEMP - Nuclear Pulse

PRI - Pulse Repetition Interval

PRT - Pulse Repetition Time

PRF - Pulse Repetition Frequency

PRP - Pulse Repetition Period

PDW - Pulse Descriptor Word

RTL - Register Transfer Level

CHAPTER 1

INTRODUCTION

1.1 Background

Electronic warfare system uses focused energy, usually radio waves or laser

light, to confuse or disable an enemy's electronics. It can also involve listening

collecting an enemy's radio signals or sensing the emitters.

1.1.1 Definition of Electronic Warfare (EW)

The official military terminology describes electronic warfare (EW) shown in

Figure 1.1 as a military action aims to control the electromagnetic spectrum (EMS).

This purpose is accomplished through offensive electronic attack (EA), defensive

electronic protection (EP), intelligence gathering and threat recognition electronic

warfare support (ES) actions. These current definitions give each function a broader

scope with respect to terminology used previously, which was, respectively, electronic

countermeasures (ECM), electronic counter-countermeasures (ECCM), and electronic

warfare support measures (ESM). Another definition for EA function, in addition to

the last ECM function, the use of direct energy weapons (DEWs), antiradiation

missiles (ARM), and electromagnetic and nuclear pulses (EMP and NEMP) to destroy

enemy electronic equipment. The new EP function definition includes, in addition to

the previous ECCM function, the use of electromagnetic emissions control (EMCON),

the electromagnetic hardening of electronic equipment, EW frequency conflict

removal, and communications security (COMSEC) actions. The new ES function

definition is not very different from the previous ESM definition as both include near-

2

real-time threat recognition in support of immediate decisions relevant to EA, EP,

weapon avoidance, and targeting actions [1].

Figure 1.1: EW subsystems [2]

1.1.2 ES Receiving System

Modern radars can usually extract much more information from the target than

just the range. They can extract angle, radial velocity, pointwise or distributed

extension, aspect changes, jet engine vs. propeller modulation, and so forth. However,

the measurement of range (i.e., the distance to a target) is still the most important radar

function. The basic radar principle is shown in Figure 1.2.

3

Figure 1.2: Block diagram of an ES receiving system [3]

1.2 Problem Statement

• Estimating an accurate pulse repetition interval (PRI) in noisy

environment leads to missing pulses.

• The slower PRI analyzing leads to slower ES system response.

• Many of electronic support (ES) system applications have physical

limitations in size, weight and power consumption (SWaP) such as in

an aircraft.

4

1.3 Objective

• The PRI Estimation Algorithm is used to determine the PRIs of the

received pulse train.

• To increase the system response speed, the received signal is analysed

using FPGA.

• To increase the respond speed, the PRI estimation system is

implemented on the FPGA.

1.4 Scope of Work

• MATLAB mathematical software is used to carry out all the simulation

of algorithms.

• The noise in signal is assumed to be additive white Gaussian noise

(AWGN).

• Threshold is chosen using Neyman-Pearson theorem.

• Radar PRI types used in this work are simple, 2-level staggered, 3-

level staggered and jitter pulses.

• The received signal data is down sampled by 150, thus makes the PRI

shorter to be used in the design and simulation.

• Quartus II software is used to design and implement algorithm on

FPGA.

5

• ModelSim is used to simulate the Verilog code.

• Algorithm verified based on data captured at DSP Lab UTM.

1.5 Research Flow

Figure 1.3 shows the flow of tasks will be performed in this project. Existing

algorithm for PRI estimation will be adjusted and tested for different PRI types in

Matlab. Then algorithm will be converted to RTL and adjusted. Later, Verilog code

will be written using Verilog HDL. Finally, algorithm will implement on FPGA in

order to test it.

Figure 1.3: Project Flow Chart

Start

Literature review

Troubleshooting

Simulation using

ModelSim

Writing Verilog

code

RTL algorithm

adjustment

Converting

algorithm into RTL

Analyse algorithm

in MATLAB

End

Is the result

verified?

No

Yes

6

1.6 Summary

This chapter discussed the introduction of this project, shadowed by brief

explanation on electronic warfare and electronic support system. Problems were

stated, objectives and scope of this project were presented.

45

REFERENCES

[1] S.-K. Lin, "Introduction to Modern EW Systems. Edited by Andrea De

Martino, Artech House, 2012; 417 pages. ISBN 978-1-60807-207-1," Sensors

(Basel, Switzerland), vol. 13, no. 1, pp. 1146-1150.

[2] A. E. Spezio, "Electronic warfare systems," IEEE Transactions on Microwave

Theory and Techniques, vol. 50, no. 3, pp. 633-644, 2002.

[3] A. W. Ata'a and S. N. Abdullah, "Deinterleaving of radar signals and PRF

identification algorithms," IET Radar, Sonar and Navigation, vol. 1, no. 5, pp.

340-347, 2007.

[4] S.-K. Lin, “Evolution of Signal Emitters and Sensors,” in introduction to

Modern EW Systems, vol. 13, no. 1, Basel, Switzerland: Sensors, 2013, ch. 2,

sec. 2.3, pp. 1146-1150.

[5] D. Adamy, Introduction to electronic warfare modeling and simulation. Artech

House, 2003.

[6] https://saab.com/globalassets/commercial/air/electronic-warfare/radar-

warning-receivers/bow/bow-product-sheet.pdf

[7] http://www.radartutorial.eu

[8] C. Wolff, Radar Tutorial (Book1): Radar Basics. Western Pommerania:

Achatweg3, 2009.

[9] D. Adamy, EW 101: A first course in electronic warfare. Artech house, 2001.

[10] K. A. Ghani, K. Dimyati, and A. Z. Sha'ameri, “Review of Pulse Repetition

Interval Analysis based on Time of Arrival,”International Defense & Security

Technology Conference, pp. 24-27, 2014.

[11] K. A. Ghani, A. Z. Sha'ameri, K. Dimyati, and N. G. N. Daud, "Pulse repetition

interval analysis using decimated Walsh-Hadamard transform," in Radar

Conference (RadarConf), 2017 IEEE, 2017, pp. 0058-0063: IEEE.

[12] C. Wolff, Radar Tutorial (Book1): Radar Basics. Western Pommerania:

Achatweg3, 2009.

[13] A. A. Ahmad, J. B. Ayeni, and S. M. Kamal, "Determination of the pulse

repetition interval (PRI) agility of an incoming radar emitter signal using

instantaneous power analysis," pp. 1-4: IEEE.

[14] V. Iglesias, J. Grajal, O. Yeste-Ojeda, M. Garrido, M. A. Sanchez, and M.

Lopez-Vallejo, "Real-time radar pulse parameter extractor," pp. 0371-0375:

IEEE.

[15] V. Iglesias, J. Grajal, P. Royer, M. A. Sanchez, M. Lopez-Vallejo, and O. A.

Yeste-ojeda, "Real-time low-complexity automatic modulation classifier for

pulsed radar signals," IEEE Transactions on Aerospace and Electronic

Systems, vol. 51, no. 1, pp. 108-126, 2015.

[16] R .Murali Prasd and J .Pandu, "FPGA Implementation of High Speed Radar

Signal Processing," in Global Journals Inc. (USA) (Global Journal of

Researches in Engineering), 2016, Volume 16 Issue 7 Version 1.0

[17] G. Stitt, "Are Field-Programmable Gate Arrays Ready for the Mainstream?,"

IEEE Micro, vol. 31, no. 6, pp. 58-63, 2011.

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[18] Altera. (2011, May). Using Floating-Point FPGAs for DSP in Radar. Altera

Corporation. U.S.A. [Online]. Retrieved on November 15, 2017, from

https://www.altera.com/en_US/pdfs/literature/wp/wp-01156-dsp-radar.pdf.

[19] J. Ender "Introduction to Radar Part 1" Scriptum of a lecture at the Ruhr-

Universtität Bochum 2011.