Introduction to Electronic Warfare Analyses

Joseph HennawyPrincipal Computer Engineer

Agenda• Introduction

– EW Definitions– ELINT Collection Cycle

• Tools of the trade– RF Receiver Characteristics– EW Antenna Design

• Areas of analyses– Direction Finding Analysis (DF)– Scan Patterns Analysis– PRI Analysis (Inter-pulse Analyses)– PDW Analysis (Intra-pulse Analyses)

• Putting things together– ESM Generic CONOPS– Sample of Future ELINT Threats

EW Definitions

DEFINITION OF ELINT• ELINT (ELECTRONIC INTELLIGENCE)

IS INFORMATION DERIVED FROM INTERCEPT AND ANALYSIS OF RADAR (NON-COMMUNICATIONS) SIGNALS.

ELINT COVERAGE

TECHNICAL vs. TACTICAL ELINT

SOME USES OF ELINT• Radar Warning Receivers (RWR) and ESM Equipment• Electronic Countermeasures (ECM) Equipment• Anti-radiation Missiles (ARM)• Anti-ship Missile Defense Systems• Simulators

RWR Uses These Parameters

• Radio Frequency (RF)• Pulse Repetition Interval (PRI) or Pulse Group Repetition Interval (PGRI)• Pulse Duration• Scan Pattern Information• Effective Radiated Power (ERP)• Beam Characteristics• Associated Emitter

ELECTRONIC WARFARE AREAS

HOW TO SPEAK EW• OLD EW

TERMINOLOGY– ECM (Electronic

Counter-measurements).– ECCM ( Electronic

Counter-Counter-Measurements).

– ESM (Electronic Support-measurements).

• NEW EW TERMINOLOGY– EP (Electronic

Protection).– EA (Electronic Attack).– ES (Electronic Support).

RF Electromagnetic Spectrum

• ELF Extremely Low Frequency 3 - 30 Hz 100,000 - 10,000 km• SLF Super Low Frequency 30 - 300 Hz 10,000 - 1,000 km• ULF Ultra Low Frequency 300 - 3000 Hz 1,000 - 100 km• VLF Very Low Frequency 3 - 30 kHz 100 - 10 km• LF Low Frequency 30 - 300 kHz 10 - 1 km• MF Medium Frequency 300 - 3000 kHz 1 km - 100 m• HF High Frequency 3 - 30 MHz 100 - 10 m• VHF Very High Frequency 30 - 300 MHz 10 - 1 m• UHF Ultra High Frequency 300 - 3000 MHz 1 m - 10 cm• SHF Super High Frequency 3 - 30 GHz 10 - 1 cm• EHF Extremely High Frequency 30 - 300 GHz 1 cm - 1 mm

Radar Frequency Band Designations

EW Frequency Band DesignationsA 30 - 250 MHzB 250 - 500 MHzC 500 - 1,000 MHzD 1 - 2 GHzE 2 - 3 GHzF 3 - 4 GHzG 4 - 6 GHzH 6 - 8 GHzI 8 - 10 GHzJ 10 - 20 GHzK 20 - 40 GHzL 40 - 60 GHzM 60 - 100 GHz

EQUIPMENT DESIGNATIONS

ELINT Collection Cycle

TECH ELINT DATA REQUIRE MENTSAND NEEDS CYCLE

TECHNICAL ELINT COLLECTION• HIGH PRIORITY:

– Threat signal.– New signals.

• METHOD: – Position collector to make intercept.– Insure that collector has measurement capability.– Record target and calibration-test signals.

• COLLECTORS: – Antenna, – receiver, – recorders, – analyzers; – special configurations vs. generic; – platform choice; – environment.

RF Receiver Characteristics

RECEIVER CHARACTERISTICS

• Gain• Dynamic Range• Distortion• Bandwidth

• Selectivity• Noise Figure• Tunability• Sensitivity • Data

Processing

Receiver GAIN

• Gain

– Ratio of Signal Out to Signal In– Power or Voltage

BAND WIDTHS• Frequency Coverage Bandwidth

– Total RF Bandwidth• Instantaneous Bandwidths

– RF Bandwidth– Noise Floor RF Bandwidth– IF Bandwidth– Video (Post Detection) Bandwidth– Noise Bandwidth

CHOOSING RECEIVERS• Application is Important

– What information do you need?– What are you going to do with the information?

• Radar warning receiver/ESM• Technical ELINT• Operational ELINT• Specific identification (SEI)

• Density– Where will you operate?– What sensitivity is required?

• Types of Signals

TYPES OF SIGNALS

THREAT SCENARIO EVOLUTION

THREAT SCENARIO EVOLUTION

Crystal Video Receiver

Narrow Band Crystal Video Receiver

Crystal Video Receiver - Parameters

Superhet IF Receiver

IFM Receiver

Multi-Stage IFM Receiver

IFM Receiver - Parameters

Channelized Receiver

Channelized Receiver - Parameters

EW Receivers

EW Receivers Vs Threat Type

MODERN MEASUREMENTSYSTEM OBJECTIVES

EW Antenna Design

What is RF gain directivity

Antenna Size/Shape vs. RF Directivity

Antenna Size/Shape & Side lobes

Antenna Patterns

Direction Finding Analysis(DF)

DF – Amplitude Comparison

DF – Phase Comparison

DF Antenna

DF Antenna

Antenna Packaging

DF-SBI

DF- SBI & LBI - Advantages

DF - Geolocation

DF – Geolocation with TDOA/FDOA techniques

T WO PLATFOR M HYBRIDDOA/TDOA/FDOA SYSTEM

TDOA vs. FDOA

Scan Patterns Analysis

ELECTRONIC RADIATION

POLARIZATION TYPES

BEAMANALYSIS

Circular Scan/PRI

Sector Scan/PRI

Raster Scan/PRI

Conical Scan/PRI

Spiral Scan

Helix Scan

V-Beam Scan (Altitude Resolution)

TWS Scan Pattern

Modern Scanning ESA passive and active

Some Applications of ESA

Other Radar Scan Patterns

Emitter Characteristics

Emitter Characteristics

Emitter Characteristics

Emitter Characteristics

PRI Analysis (Inter-pulse Analyses)

PRI Analyses

Uses of PRI

RPI vs. Range and Velocity

Performance can be improved using FMOP and/or PMOP

PRI Staggers

Jittered PRI

Dwell-Switched PRI

Sliding PRI

Periodic and Pulse-Interval Displacement PRI

Interrupted And Burst PRI

New Radars – Scheduled PRI

Pulse Grouping PRI

PRI Analyses - Summary

PDW Analysis (Intra-pulse Analyses)

PDW Analyses

CALCULATION OFAMPLITUDE,TOA,PW

ESM Generic CONOPS

ELINT Processing - I

• Today’s systems rely on processing each received radar pulse (PDW). Measurements typically include Pulse width, RF, Time of Arrival (TOA), and Angle of Arrival (AOA).

• Pulses are sorted into “clusters” believed to have come from the same transmitter by matching PW, RF, AOA– note RF is not constant for Frequency Agile signals.

These require added processing.

ELINT Processing – II

• Based on the clustering results, pulses are placed into pulse trains if they have “sensible” TOA sequences

• Then PRI parameters are determined– PRI value– PRI Jitter values– Stagger sequence and period or “stable sum”

ELINT Processing – III

• If threats operate with other related transmissions, the narrow band receiver may look for the associated signals

• If pulses have the same PW and AOA but differing RFs, one may conclude that it is a frequency agile threat

• AOA is normally a fixed value over many pulses even for moving threats. DF and Geo processing can be performed on the threat.

ELINT Processing – IV

• The ID tables used in ESM systems are built using the results of Electronic Intelligence (ELINT) efforts over long periods of time

• The ESM user customizes the world wide threat data to his region of operations Non-threatening signals must be handled, too (Own-ship blanking)

ELINT Processing – V

• Threat Identification is done by measuring signal parameters and using table look up

• ID Table data (initially) comes from Intelligence holdings

• Parameter variations and mimicking other signals are ways to degrade ID

• Generic Threat ID is a possibility

Sample of Future ELINT Threats

Future ELINT Threats – I LPI Emitters

• New types of emitters that spreads their power over time, instead of sending instantaneous high power.

• Difficult to detect by traditional EW assets.• Needs need EW assets, and CONOPS

that will dwell on a receiver and integrate its power over time.

• Frequency agiles are not LPI in terms of this power definition.

Future ELINT Threats – II Frequency Hopping Emitters

• Frequency Hoppers are emitters that switches their carrier frequency over a wide band of frequencies to avoid exploitation and/or detection.

• Hoppers are a feature of modern communications hardware, and soon to be a common feature of radar assets, with the advanced is digital processing and DSP techniques.

Future ELINT Threats – III Spread Spectrum Emitters

• Other Future hopper-like radar systems could be called “Spread Spectrum” if they coherently combine the echoes in several range cells prior to making target detection decisions

• Coherently combining the echoes means adjusting the phase of the echoes in adjacent range cells prior to adding them together.

• This requires more signal processing and cost, but could happen