Download EW 104_ Electronic Warfare Agai - David L. Adamy PDF

TitleEW 104_ Electronic Warfare Agai - David L. Adamy
File Size18.1 MB
Total Pages491
Table of Contents
                            Title Page
Copyright Page
Dedication
Contents
Preface
1 Introduction
2 Spectrum Warfare
	2.1 Changes in Warfare
	2.2 Some Specific Propagation Related Issues
	2.3 Connectivity
		2.3.1 The Most Basic Connectivity
		2.3.2 Connectivity Requirements
		2.3.3 Long-Range Information Transmission
		2.3.4 Information Fidelity
	2.4 Interference Rejection
		2.4.1 Spreading the Transmitted Spectrum
		2.4.2 Commercial FM Broadcast
		2.4.3 Military Spread Spectrum Signals
	2.5 Bandwidth Requirements for Information Transfer
		2.5.1 Data Transfer Without a Link
		2.5.2 Linked Data Transmission
		2.5.3 Software Location
	2.6 Distributed Military Capability
		2.6.1 Net-Centric Warfare
	2.7 Transmission Security Versus Message Security
		2.7.1 Transmission Security Versus Transmission Bandwidth
		2.7.2 Bandwidth Limitations
	2.8 Cyber Warfare Versus EW
		2.8.1 Cyber Warfare
		2.8.2 Cyber Attacks
		2.8.3 Parallels Between Cyber Warfare and EW
		2.8.4 Difference Between Cyber Warfare and EW
	2.9 Bandwidth Trade-Offs
		2.9.1 Bit-Error Critical Cases
	2.10 Error Correction Approaches
		2.10.1 Error Detection and Correction Codes
		2.10.2 Example of a Block Code
		2.10.3 Error Correction Versus Bandwidth
	2.11 EMS Warfare Practicalities
		2.11.1 Warfare Domains
	2.12 Steganography
		2.12.1 Steganography Versus Encryption
		2.12.2 Early Stenographic Techniques
		2.12.3 Digital Techniques
		2.12.4 How Does Steganography Relate to Spectrum Warfare?
		2.12.5 How Is Steganography Detected?
	2.13 Link Jamming
		2.13.1 Communication Jamming
		2.13.2 Required J/S for Jamming Digital Signals
		2.13.3 Protections Against Link Jamming
		2.13.4 The Net Impact on Link Jamming
3 Legacy Radars
	3.1 Threat Parameters
		3.1.1 Typical Legacy Surface-to-Air Missile
		3.1.2 Typical Legacy Acquisition Radar
		3.1.3 Typical Anti-Aircraft Gun
	3.2 EW Techniques
	3.3 Radar Jamming
		3.3.1 Jamming-to-Signal Ratio
		3.3.2 Self-Protection Jamming
		3.3.3 Remote Jamming
		3.3.4 Burn-Through Range
	3.4 Radar-Jamming Techniques
		3.4.1 Cover Jamming
		3.4.2 Barrage Jamming
		3.4.3 Spot Jamming
		3.4.4 Swept Spot Jamming
		3.4.5 Deceptive Jamming
		3.4.6 Range Deception Techniques
		3.4.7 Angle Deceptive Jamming
		3.4.8 Frequency Gate Pull Off
		3.4.9 Jamming Monopulse Radars
		3.4.10 Formation Jamming
		3.4.11 Formation Jamming with Range Denial
		3.4.12 Blinking
		3.4.13 Terrain Bounce
		3.4.14 Cross-Polarization Jamming
		3.4.15 Cross-Eye Jamming
			Reference
4 Next Generation Threat Radars
	4.1 Threat Radar Improvements
	4.2 Radar Electronic Protection Techniques
		4.2.1 Useful Resources
		4.2.2 Ultralow Side Lobes
		4.2.3 EW Impact of Reduced Side-Lobe Level
		4.2.4 Side-Lobe Cancellation
		4.2.5 Side-Lobe Blanking
		4.2.6 Monopulse Radar
		4.2.7 Cross-Polarization Jamming
		4.2.8 Anti-Cross-Polarization
		4.2.9 Chirped Radar
		4.2.10 Barker Code
		4.2.11 Range Gate Pull-Off
		4.2.12 AGC Jamming
		4.2.13 Noise-Jamming Quality
		4.2.14 Electronic Protection Features of Pulse Doppler Radars
		4.2.15 Configuration of Pulse Doppler Radar
		4.2.16 Separating Targets
		4.2.17 Coherent Jamming
		4.2.18 Ambiguities in PD Radars
		4.2.19 Low, High, and Medium PRF PD Radar
		4.2.20 Detection of Jamming
		4.2.21 Frequency Diversity
		4.2.22 PRF Jitter
		4.2.23 Home on Jam
	4.3 Surface-to-Air Missile Upgrades
		4.3.1 S-300 Series
		4.3.2 SA-10 and Upgrades
		4.3.3 SA-12 and Upgrades
		4.3.4 SA-6 Upgrades
		4.3.5 SA-8 Upgrades
		4.3.6 MANPADS Upgrades
	4.4 SAM Acquisition Radar Upgrade
	4.5 AAA Upgrades
	4.6 EW Implications of Capabilities Described
		4.6.1 Increased Lethal Range
		4.6.2 Ultralow Side Lobes
		4.6.3 Coherent Side-Lobe Cancelling
		4.6.4 Side-Lobe Blanking
		4.6.5 Anti-Cross-Polarization
		4.6.6 Pulse Compression
		4.6.7 Monopulse Radar
		4.6.8 Pulse-Doppler Radar
		4.6.9 Leading-Edge Tracking
		4.6.10 Dicke-Fix
		4.6.11 Burn-Through Modes
		4.6.12 Frequency Agility
		4.6.13 PRF Jitter
		4.6.14 Home-on-Jam Capability
		4.6.15 Improved MANPADS
		4.6.16 Improved AAA
			Reference
5 Digital Communication
	5.1 Introduction
	5.2 The Transmitted Bit Stream
		5.2.1 Transmitted Bit Rate Versus Information Bit Rate
		5.2.2 Synchronization
		5.2.3 Required Bandwidth
		5.2.4 Parity and EDC
	5.3 Protecting Content Fidelity
		5.3.1 Basic Fidelity Techniques
		5.3.2 Parity Bits
		5.3.3 EDC
		5.3.4 Interleaving
		5.3.5 Protecting Content Fidelity
	5.4 Digital Signal Modulations
		5.4.1 Single Bit per Baud Moduatlions
		5.4.2 Bit Error Rates
		5.4.3 m-ary PSK
		5.4.4 I&Q Modulations
		5.4.5 BER Versus Eb/N0 for Various Modulations
		5.4.6 Efficient Bit Transition Modulation
	5.5 Digital Link Specifications
		5.5.1 Link Specifications
		5.5.2 Link Margin
		5.5.3 Sensitivity
		5.5.4 Eb/N0 Versus RFSNR
		5.5.5 Maximum Range
		5.5.6 Minimum Link Range
		5.5.7 Data Rate
		5.5.8 Bit Error Rate
		5.5.9 Angular Tracking Rate
		5.5.10 Tracking Rate Versus Link Bandwidth and Antenna Types
		5.5.11 Weather Considerations
		5.5.12 Antispoof Protection
	5.6 Antijam Margin
	5.7 Link Margin Specifics
	5.8 Antenna Alignment Loss
	5.9 Digitizing Imagery
		5.9.1 Video Compression
		5.9.2 Forward Error Correction
	5.10 Codes
		Reference
6 Legacy Communication Threats
	6.1 Introduction
	6.2 Communications Electronic Warfare
	6.3 One-Way Link
	6.4 Propagation Loss Models
		6.4.1 Line-of-Sight Propagation
		6.4.2 Two-Ray Propagation
		6.4.3 Minimum Antenna Height for Two-Ray Propagation
		6.4.4 A Note About Very Low Antennas
		6.4.5 Fresnel Zone
		6.4.6 Complex Reflection Environment
		6.4.7 Knife-Edge Diffraction
		6.4.8 Calculation of KED
	6.5 Intercept of Enemy Communication Signals
		6.5.1 Intercept of a Directional Transmission
		6.5.2 Intercept of a Nondirectional Transmission
		6.5.3 Airborne Intercept System
		6.5.4 Non-LOS Intercept
		6.5.5 Intercept of Weak Signal in Strong Signal Environment
		6.5.6 Search for Communications Emitters
		6.5.7 About the Battlefield Communications Environment
		6.5.8 A Useful Search Tool
		6.5.9 Technology Issues
		6.5.10 Digitally Tuned Receiver
		6.5.11 Practical Considerations Effecting Search
		6.5.12 A Narrowband Search Example
		6.5.13 Increase the Receiver Bandwidth
		6.5.14 Add a Direction Finder
		6.5.15 Search with a Digital Receiver
	6.6 Location of Communications Emitters
		6.6.1 Triangulation
		6.6.2 Single Site Location
		6.6.3 Other Location Approaches
		6.6.4 RMS Error
		6.6.5 Calibration
		6.6.6 CEP
		6.6.7 EEP
		6.6.8 Site Location and North Reference
		6.6.9 Moderate Accuracy Techniques
		6.6.10 Watson-Watt Direction Finding Technique
		6.6.11 Doppler Direction Finding Technique
		6.6.12 Location Accuracy
		6.6.13 High-Accuracy Techniques
		6.6.14 Single Baseline Interferometer
		6.6.15 Multiple Baseline Precision Interferometer
		6.6.16 Correlative Interferometer
		6.6.17 Precision Emitter Location Techniques
		6.6.18 TDOA
		6.6.19 Isochrones
		6.6.20 FDOA
		6.6.21 Frequency Difference Measurement
		6.6.22 TDOA and FDOA
		6.6.23 Calculation of CEP for TDOA and FDOA Emitter Location Systems
		6.6.24 References That Give Closed Form Formulas for TDOA and FDOA Accuracy
		6.6.25 Scatter Plots
		6.6.26 Precision Location of LPI Emitters
	6.7 Communication Jamming
		6.7.1 Jam the Receiver
		6.7.2 Jamming a Net
		6.7.3 Jamming-to-Signal Ratio
		6.7.4 Propagation Models
		6.7.5 Ground-Based Communication Jamming
		6.7.6 Formula Simplification
		6.7.7 Airborne Communications Jamming
		6.7.8 High Altitude Communication Jammer
		6.7.9 Stand-In Jamming
		6.7.10 Jam Microwave UAV Link
			Reference
7 Modern Communications Threats
	7.1 Introduction
	7.2 LPI Communication Signals
		7.2.1 Processing Gain
		7.2.2 Antijam Advantage
		7.2.3 LPI Signals Must Be Digital
	7.3 Frequency-Hopping Signals
		7.3.1 Slow and Fast Hoppers
		7.3.2 Slow Hopper
		7.3.3 Fast Hopper
		7.3.4 Antijam Advantage
		7.3.5 Barrage Jamming
		7.3.6 Partial-Band Jamming
		7.3.7 Swept Spot Jamming
		7.3.8 Follower Jammer
		7.3.9 FFT Timing
		7.3.10 Propagation Delays in Follower Jamming
		7.3.11 Jamming Time Available
		7.3.12 Slow Hop Versus Fast Hop
	7.4 Chirp Signals
		7.4.1 Wide Linear Sweep
		7.4.2 Chirp on Each Bit
		7.4.3 Parallel Binary Channels
		7.4.4 Single Channel with Pulse Position Diversity
	7.5 Direct Sequence Spread Spectrum Signals
		7.5.1 Jamming DSSS Receivers
		7.5.2 Barrage Jamming
		7.5.3 Pulse Jamming
		7.5.4 Stand-In Jamming
	7.6 DSSS and Frequency Hop
	7.7 Fratricide
		7.7.1 Fratricide Links
		7.7.2 Minimizing Fratricide
	7.8 Precision Emitter Location of LPI Transmitters
	7.9 Jamming Cell Phones
		7.9.1 Cell Phone Systems
		7.9.2 Analog Systems
		7.9.3 GSM Systems
		7.9.4 CDMA Systems
		7.9.5 Cell Phone Jamming
		7.9.6 Uplink Jamming from the Ground
		7.9.7 Uplink Jamming from the Air
		7.9.8 Downlink Jamming from the Ground
		7.9.9 Downlink Jamming from the Air
			Reference
8 Digital RF Memories
	8.1 DRFM Block Diagram
	8.2 Wideband DRFM
	8.3 Narrowband DRFM
	8.4 DRFM Functions
	8.5 Coherent Jamming
		8.5.1 Increased Effective J/S
		8.5.2 Chaff
		8.5.3 RGPO and RGPI Jamming
		8.5.4 Radar Integration Time
		8.5.5 Continuous-Wave Signals
	8.6 Analysis of Threat Signals
		8.6.1 Frequency Diversity
		8.6.2 Pulse-to-Pulse Frequency Hopping
	8.7 Noncoherent Jamming Approaches
	8.8 Follower Jamming
	8.9 Radar Resolution Cell
		8.9.1 Pulse Compression Radar
		8.9.2 Chirp Modulation
		8.9.3 Role of DRFM
		8.9.4 Barker Code Modulation
		8.9.5 Jamming Barker Coded Radars
		8.9.6 Impact on Jamming Effectiveness
	8.10 Complex False Targets
		8.10.1 The Radar Cross Section
		8.10.2 Generating RCS Data
		8.10.3 Computed RCS Data
	8.11 DRFM-Enabling Technology
		8.11.1 Capturing Complex Targets
		8.11.2 DRFM Configuration
	8.12 Jamming and Radar Testing
	8.13 DRFM Latency Issues
		8.13.1 Identical Pulses
		8.13.2 For Identical Chirped Pulses
		8.13.3 For Identical Barker Coded Pulses
		8.13.4 For Unique Pulses
		8.14 A Summary of Radar Techniques That Call for DRFM-Based Countermeasures
		8.14.1 Coherent Radars
		8.14.2 Leading-Edge Tracking
		8.14.3 Frequency Hopping
		8.14.4 Pulse Compression
		8.14.5 Range Rate/Doppler Shift Correlation
		8.14.6 Detailed Analysis of Radar Cross Section
		8.14.7 High Duty-Cycle Pulse Radars
			Reference
9 Infrared Threats and Countermeasures
	9.1 The Electromagnetic Spectrum
	9.2 IR Propagation
		9.2.1 Propagation Loss
		9.2.2 Atmospheric Attenuation
	9.3 Black-Body Theory
	9.4 Infrared-Guided Missiles
		9.4.1 IR Missile Components
		9.4.2 IR Seeker
		9.4.3 Reticles
		9.4.4 IR Sensors
	9.5 Additional Tracking Reticles
		9.5.1 Wagon Wheel Reticle
		9.5.2 Multiple Frequency Reticle
		9.5.3 Curved Spoke Reticle
		9.5.4 Rosette Tracker
		9.5.5 Crossed Linear Array Tracker
		9.5.6 Imaging Tracker
	9.6 IR Sensors
		9.6.1 Aircraft Temperature Characteristics
	9.7 Atmospheric Windows
	9.8 Sensor Materials
	9.9 One-Color Versus Two-Color Sensors
	9.10 Flares
		9.10.1 Seduction
		9.10.2 Distraction
		9.10.3 Dilution
		9.10.4 Timing Issues
		9.10.5 Spectrum and Temperature Issues
		9.10.6 Temperature-Sensing Trackers
		9.10.7 Rise Time-Related Defense
		9.10.8 Geometric Defenses
		9.10.9 Operational Safety Issues for Flares
		9.10.10 Flare Cocktails
	9.11 Imaging Trackers
		9.11.1 Imaging Tracker Engagement
		9.11.2 Acquisition
		9.11.3 Mid-Course
		9.11.4 End Game
	9.12 IR Jammers
		9.12.1 Hot-Brick Jammers
		9.12.2 Effect of Jammer on Tracker
		9.12.3 Laser Jammers
		9.12.4 Laser Jammer Operational Issues
		9.12.5 Jamming Waveforms
10 Radar Decoys
	10.1 Introduction
		10.1.1 Missions of Decoys
		10.1.2 Passive and Active Radar Decoys
		10.1.3 Deployment of Radar Decoys
	10.2 Saturation Decoys
		10.2.1 Saturation Decoy Fidelity
		10.2.2 Airborne Saturation Decoys
		10.2.3 The Radar Resolution Cell
		10.2.4 Shipboard Saturation Decoys
		10.2.5 Detection Decoys
	10.3 Seduction Decoys
	10.4 Expendable Decoys
		10.4.1 Aircraft Decoys
		10.4.2 Antenna Isolation
		10.4.3 Aircraft Distraction Decoys
		10.4.4 Aircraft Seduction Decoys
	10.5 Ship-Protection Seduction Decoys
		10.5.1 Ship Seduction Decoy RCS
		10.5.2 Decoy Deployment
		10.5.3 Dump Mode
	10.6 Towed Decoys
		10.6.1 The Resolution Cell
		10.6.2 An Example
11 Electromagnetic Support Versus Signal Intelligence
	11.1 Introduction
	11.2 SIGINT
		11.2.1 COMINT and Communications ES
		11.2.2 ELINT and Radar ES
	11.3 Antenna and Range Considerations
	11.4 Antenna Issues
	11.5 Intercept Range Considerations
	11.6 Receiver Considerations
	11.7 Frequency Search Issues
	11.8 Processing Issues
	11.9 Just Add a Recorder
		Reference
About the Author
Index
                        
Document Text Contents
Page 245

AOA of the signal. Emitter location is determined from one of the techniques (such as
triangulation) discussed earlier.

We will begin by discussing single baseline interferometers and then will cover
correlative and multiple baseline interferometers.

6.6.14 Single Baseline Interferometer
Although virtually all interferometer systems employ multiple baselines, the single
baseline interferometer uses one baseline at a time. The presence of multiple baselines
allows for the resolution of ambiguities. It also allows multiple, independent
measurements to be averaged to reduce the impact of multipath and other equipment-
based sources of error.

Figure 6.58 is a basic block diagram of an interferometric DF system. Signals from
two antennas are compared in phase, and the DOA of the signal is determined from the
measured phase difference. Remember that we characterize the transmitted signal as a sine
wave traveling at the speed of light. One cycle (360 phase degrees) of the traveling sine
wave is called the wavelength. The relation between the frequency of the transmitted
signal and its wavelength is defined by the formula:

c = λf

where c is the speed of light (3 × 108 m/s), λ is the wavelength (in meters), and f is the
frequency in cycles per second (units are 1/sec).

The interferometric principle is best explained by consideration of the interferometric
triangle as shown in Figure 6.59. The two antennas from Figure 6.58 form a baseline. It is
assumed that the distance between the two antennas and their precise location are known
precisely. The wavefront is a line perpendicular to the direction from which the signal is
arriving at the direction finding station. This is a line of constant phase for the arriving
signal. The signal expands spherically from the transmitting antenna, so the wavefront is
actually a circular segment. However, since the baseline can be assumed to be much
shorter than the distance from the transmitter, it is very reasonable to show the wavefront
as a straight line in this drawing. The precise location of the station is taken to be the
center of the baseline. Because the signal has the same phase along the wavefront, the
phases at point A and point B are equal. Hence, the phase difference between the signals at
the two antennas (i.e., points A and C) is equal to the phase difference between the signal
at points B and C.

Page 246

Figure 6.58 The interferometer compares the phase of a signal at two antennas and uses the phase difference to
calculate the angle of arrival.

Figure 6.59 The operation of an interferometer is best understood through consideration of the interferometric
triangle.

The length of line BC is known from the formula:

BC = ΔΦ(λ/360°)

where ΔΦ is the phase difference and λ is the signal wavelength.

The angle at point B in the diagram is 90° by definition, so the angle at point A (call it
angle A) is defined by:

A = arcsin(BC/AC)

where AC is the length of the baseline.

The AOA of the signal is reported out relative to the perpendicular to the baseline at its
center point, because the interferometer provides maximum accuracy at that angle. Note
that the ratio of phase degrees to angular degrees is maximum here. By construction, you
can see that angle D is equal to angle A.

Page 490

resolution cell, 405

See also Decoys

Trackers

crossed linear array, 350

effect of jammer on, 372–73

imaging, 350–51, 366–70

rosette, 349–50

temperature-sensing, 359–60

Tracking rate

angular, 155–56

link bandwidth versus, 156

Tracking reticles, 346–51

Track-while scan (TWS) radar, 73

Transmission security

on links from higher value assets, 27

message security versus, 25–30

requirement, 16

spread spectrum (SS), 43

transmission bandwidth versus, 29

Transmitted bit stream

parity and EDC, 137

required bandwidth, 136–37

signals, 133–34

synchronization, 134–35

transmitted bit rate versus information bit rate and, 134

Transmitter power, 55

Triangulation

illustrated, 206

in location of communications transmitters, 205–8

moving DF system, 207

sites, 207

Trojan horses, 31

Page 491

Two-color sensors, 354–55

Two-ray propagation

decibel formula, 179–80

defined, 178

dominant loss effect, 179

minimum antenna height for, 180–81

Ultralow side lobes

ES system detection and, 127

EW impact, 89–91

gain pattern, 88, 89

J/S, 90

Uplink jamming, cell phone

from air, 295–96

from ground, 293–95

Velocity gate pull-off (VGPO), 109

Video compression, 165–66

Viruses, 31

Voice communication, 10

Wagon wheel reticle, 346–47

Watson-Watt direction finding technique, 219–20

Wavelet compression, 165

Weak signal intercept, in strong signal

environment, 193–94

Weather, 156–58

Wideband DRFM

defined, 300

frequency conversion, 301

jammer system, 300–301

sampling generation approaches, 301–2

See also Digital RF memory (DRFM)

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