Introduction to Radar Warning Receiver
Short Description
Download Introduction to Radar Warning Receiver...
Description
2/23/2009
Introduction to Radar Warning Receivers Robins AFB February 24, 2009 Presenter: Kim Cole
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-1
What is a Radar Warning Receiver? • A Radar Warning Receiver (RWR) is a passive EW
system that does the following: • Detects RF signals transmitted by radar systems • Identifies the signal by radar type • Manages detected signals • Generates visual and audio cues to pilot • Manages interfaces to other systems
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-2
What the Pilot Sees
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-3
1
2/23/2009
ALR-69 System Block Diagram CVR SUBSYSTEM
CVR 135 AM-423 45
CVR 45
J1
J1
E, G, I (135)
AM-423 135
J3
J2 J3
CVR 225
CVR 315
J1
AM-423 225
AS-3305 (45) (135) (Omni) (315) (225)
CM-479
E, G, I (45)
J2
E, G, I (225)
E, G, I (315)
ALQ-213 CMSP IP1310 F1
2X 2Y J1
J3
J1 F2
J4
J2
Diamond Audio
J2
J2
J3
J3
E, G, I Band Video (45, 135, 225, 315) C/D Band Video (45, 135, 225, 315) Omni Video
AM-423 315 AM-6971
J1 J2 J5 J4 J3
J6
J3
J1
J5
HSDB J4
J2 N1
J7
ANT7
C/D, E, G, I Band Static Video (TTL)
FSRS Subsystem AM-423 135 (FSRS)
J2
AM-423 45 (FSRS)
J1
AM-423 225 (FSRS)
AM-423 315 (FSRS)
F1 F2
J3
J1 J5
J2
J3
J3 J4
F3
R-2094 J1
J6
C-10373
Antenna Control (0-3)
SA-2263
J5
J2
J4
RI/D, Control (0-3), CW Strobe, PRF Window Rec. Int., Discrimn. Video, Bandpass Video
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-4
ALR-69 System
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-5
What the Pilot Sees
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-6
2
2/23/2009
(Very) Brief History of RWR
• RWRs have been around for about 40 years. • First-generation RWRs were used by the US Air Force
during the Vietnam War in response to Russian radarguided SAMs deployed in North Vietnam. • The Israelis suffered heavy losses to radar-directed
AAA and SAMs during the 1973 Yom Kippur War.
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-7
Example USAF RWR Installations
RWR Type
Aircraft
ALR-56C
F-15
ALR-56M
F-16, C-130, B-1
ALR-69
B-52, A-10, C-130, F-16, C-130
ALR-94
F-22
APR-39
C-130, V-22
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-8
How Does an RWR Work? • Hardware handles detection • Hardware detects radar pulses and converts pulse parameters to
digital format • Major hardware components: antennas, RF cables, receiver,
signal processor, user I/O devices
• Software handles identification and aircrew interface • Software processes digital data to determine what type of radar
system is illuminating the aircraft and then provides aircrew cues • Major software components: operational flight program and
mission data file
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-9
3
2/23/2009
Why Do You Need an RWR? • The enemy is out there! • The enemy has air defense systems that are very
dependent on radar and RF-guided weapons. • They have surface-to-air-missiles (SAMs), anti-aircraft
artillery (AAA), and air-to-air missiles that are cued/targeted/guided by RF signals. • When an enemy radar points at a USAF aircraft, we
can detect that signal and warn the aircrew of the presence of that weapon system. GTRI_B-10
Copyright by Georgia Tech Research Corporation, 2009
Typical Air Defense System Encounter
MISSILE LAUNCHER
COMMAND STATION
MISSILE TRACKER COMPUTER VAN TARGET TRACKER
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-11
SA-2 Surface to Air Missile
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-12
4
2/23/2009
RWR Operational Concept 0
7 8
7
0
8 Processor
GTRI_B-13
Copyright by Georgia Tech Research Corporation, 2009
How Do We Measure RWR Performance? • Typical RWR measures of performance (MOPs) are: • Detection range • Response time • Correct ID • DF accuracy • Age out
• Performance is usually measured by conducting a
flight test on an open-air range. GTRI_B-14
Copyright by Georgia Tech Research Corporation, 2009
Simplified RWR Processing Flow
Input Buffer
RF
Signal Detection Hardware
Signal Processing
Emitter Track File
Manage Interfaces
Software
Copyright by Georgia Tech Research Corporation, 2009
Software
GTRI_B-15
5
2/23/2009
Origin of RWR Input
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-16
RWR Frequency Coverage • A typical RWR detects pulsed radar signals in the
0.5-18 GHz frequency range. • Frequency is measured in “Hertz” • Hertz is a unit of frequency of one cycle per second. 6 Hertz 3 Hertz
One second
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-17
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-18
6
2/23/2009
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-19
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-20
Types of Radar Signals • Continuous Wave
• Pulsed
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-21
7
2/23/2009
Quick Word About Notation for Pulsed Signals
All meant to illustrate the same concept.
Time
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-22
What Measurements Does an RWR Make? • For each CW signal the RWR will measure: • Frequency, angle of arrival, and power
• For each pulse in a pulsed signal the RWR will
measure: • Frequency or frequency band, time of arrival (TOA),
angle of arrival (AOA or DF), pulse width, and power • For CW or pulsed signals outside the RF coverage
of the RWR, no measurement is made.
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-23
First Step: Detect Signal with Antenna E/J Band antenna Four per aircraft
C/D Band antenna One per aircraft
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-24
8
2/23/2009
First Step: Detect Signal with Antenna
315°
45°
Four E/J band antennas are installed at quadrant locations around aircraft. 225°
Copyright by Georgia Tech Research Corporation, 2009
135°
GTRI_B-25
F-16 Forward Antenna Installation
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-26
F-16 Aft Antenna Installation
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-27
9
2/23/2009
Converting RF Pulse to Digital Data Quadrant antennas
Pulse Measurement Data
Receiver
To software For Signal processing
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-28
Basic Analog Receivers1 (1/2) Receiver
Advantage
Disadvantage
Wideband Crystal Video
Simple; Inexpensive Instantaneous High POI in frequency range
No frequency resolution Poor sensitivity Poor simultaneous signal
Tuned RF Crystal Video
Simple Frequency measurement Higher sensitivity than wideband
Slow response time Poor POI
IFM
Relatively simple Frequency resolution Instantaneous; High POI
Simultaneous signal problem Relatively poor sensitivity
Narrow Band Scanning Superhet
High sensitivity Good frequency resolution No simultaneous signals problem
Slow Response Poor POI Poor against freq agility
Wideband Superhet
Better response time Better POI
Spurious signals generated Poorer sensitivity
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-29
Basic Analog Receivers1 (2/2) Receiver
Advantage
Disadvantage
Channelized
Wide bandwidth Near instantaneous Moderate frequency resolution
High complexity, cost Lower reliability Limited sensitivity
Microscan
Near instantaneous Good frequency resolution Good dynamic range Good simultaneous signal capability
High complexity Limited bandwidth No pulse modulation information Critical alignment
Acousto-optic
Near instantaneous Good frequency resolution Good simultaneous signal capability Good POI
High complexity New technology
1 Electronic Warfare And
Radar Systems Engineering Handbook, NAWCWPNS TP 8347, April 1, 1999
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-30
10
2/23/2009
Most Common RWR Receiver Architectures
Crystal Video Receiver RF Amplifier
Compressive Video Amplifier Band 1 Video
Multiplexer
Band 2 Video
Tuned Narrowband Superhet IF Amp RF Filter Tuning
Band 3 Video
IF Filter
Log Video Amp
Video
Local Oscillator
Copyright by Georgia Tech Research Corporation, 2009
Filename - 31
GTRI_B-31
Narrow-Band Superheterodyne Receiver • Narrow bandwidth • -90 dBm sensitivity • Low probability of intercept (POI) • Good signal separation • Measures frequency, PW, power, and AOA • Excellent CW Capability • Medium cost • Medium volume Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-32
Wideband Crystal Video Receiver • Wide instantaneous bandwidth • - 45 dBm sensitivity • High probability of intercept • Poor signal separation • Measures frequency band, PW, power, and AOA • Poor CW Capability • Low cost • Small volume Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-33
11
2/23/2009
Input Scheduling • Another important RWR term is input scheduling. • Both superhet and CVR architectures require
sophisticated input schedulers. • The input schedule is usually defined in the mission
data file. • We have said that a typical RWR covers the 0.5-18
GHz frequency range, but they typically do not collect inputs from the entire range at one time. GTRI_B-34
Copyright by Georgia Tech Research Corporation, 2009
CVR Input Scheduling • A typical CVR RF signal is fed to an
amplifier/detector that splits the covered RF range into multiple frequency bands. • A typical CVR looks (collects input) from a single RF
band at a time. • Example band breaks are shown below. Band 0
Band 1 2 GHz
0.5 GHz
Band 2 8 GHz
Band 3 12 GHz
18 GHz
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-35
Example CVR Input Schedules More realistic schedule Really simple schedule Band Look Time
Band
Look Time
0
10 ms
0
25 ms
1
12 ms
1
25 ms
2
15 ms
2
25 ms
3
15 ms
3
25 ms
0
50 ms (conditional)
2
1 ms
3
1 ms
1
20 ms
3
25 ms
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-36
12
2/23/2009
Simple Probability of Intercept Example Scanning threat radar
RWR input scheduler Band 0
Band 1
Band 2
Band 3
Band 0
Filename - 37
GTRI_B-37
Copyright by Georgia Tech Research Corporation, 2009
Emitter Transmitted Frequency Range Threat ID A B C D E F G H I J K L M N O P Q R 2
4
6
8
10 RF (GHz)
12
14
16
18
GTRI_B-38
Copyright by Georgia Tech Research Corporation, 2009
Superhet Input Scheduler • The input schedule for a superhet receiver is much
more complex than the input schedule for a CVR. • This is because the superhet is a narrow-band
receiver, i.e. the total frequency range is broken into many smaller segments that must be covered. • Superhet input schedulers contain more numerous,
shorter looks.
0.5 GHz
2 GHz
8 GHz
12 GHz
Copyright by Georgia Tech Research Corporation, 2009
18 GHz
GTRI_B-39
13
2/23/2009
Pulse Measurements
• If the RWR detects a pulse, it collects a set of data
for that pulse. • The formats differ among various RWRs, but this
pulse data is generally called a pulse descriptor word (PDW). • The PDW contains all data collected for a single RF
pulse.
GTRI_B-40
Copyright by Georgia Tech Research Corporation, 2009
Pulse Descriptor Word • A typical PDW contains time of arrival (TOA), angle,
pulse width, power, and frequency (superhet) or frequency band (CVR). • The ALR-69 PDW format is shown below: 0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
TIME OF ARRIVAL (16 LSBs) PULSE WIDTH
TIME OF ARRIVAL (8 MSBs)
POWER IP
PP FO1 FO2 PRI
ANGLE DT RB1 RB2 DCB COR CDM B0
B1
B2
B3
B4
GTRI_B-41
Copyright by Georgia Tech Research Corporation, 2009
Key Pulse Parameters Frequency
Pulsewidth
Power
PRI “PRI” is Pulse Repetition Interval. Time
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-42
14
2/23/2009
Input Buffer
• The final output of the Signal Detection component
of the RWR is an Input Buffer. • An Input Buffer is a series of PDWs that were
collected during a single look. • The Input Buffer is processed by the RWR software
to determine what type radar (or radars) transmitted the pulses.
GTRI_B-43
Copyright by Georgia Tech Research Corporation, 2009
Simplified RWR Processing Flow
Input Buffer
RF
Signal Detection
Signal Processing
Hardware
Emitter Track File
Manage Interfaces
Software
Software
GTRI_B-44
Copyright by Georgia Tech Research Corporation, 2009
OFP and MDF Operational Flight Program (OFP)
• Executable code • Input scheduler • PRI deinterleaver • Track file management • Missile guidance
Mission Data File (MDF)
• Data (no executable
code) • Input schedule • Threat identification • Threat information • Ambiguity resolve tables
algorithms • Interface management
• Missile guidance data
Copyright by Georgia Tech Research Corporation, 2009
Filename - 45
GTRI_B-45
15
2/23/2009
Major Signal Processing Components
Emitter Track File
Input Buffer PRI Deinterleave
Ambiguity Resolve
Threat ID
Track File Management
Filename - 46
GTRI_B-46
Copyright by Georgia Tech Research Corporation, 2009
PRI Deinterleaving Algorithm • Many years of research have been done regarding
PRI deinterleaving algorithms. • The PRI deinterleaving algorithm is the most
complex algorithm, and uses the most processor time, of any function in an RWR OFP. Input Buffer
Pulse train statistics: Frequency/band PRI Power Angle Pulse width PRI agility info Quality statistics
PRI Deinterleave
GTRI_B-47
Copyright by Georgia Tech Research Corporation, 2009
PRI Agility Stable • For a “stable PRI” emitter the interpulse period is
the same for every pulse. 175
175
175
175
175
175
175
175
175
175
175
175
175
175
175
175
175
Copyright by Georgia Tech Research Corporation, 2009
175
175
175
175
175
GTRI_B-48
16
2/23/2009
PRI Agility Stagger • For a “staggered PRI” emitter, a set of interpulse
periods are repeated continuously. • 2-level stagger 150
175
150
175
150
175
150
175
150
175
150
175
150
175
150
175
150
175
150
175
150
175
175
225
150
175
225
150
175
225
150
175
225
150
175
225
150
200
150
175
125
200
150
175
125
200
150
175
125
200
150
175
• 3-level stagger 150
175
225
150
175
225
150
• 4-level stagger 150
175
125
200
150
175
125
GTRI_B-49
Copyright by Georgia Tech Research Corporation, 2009
PRI Agility Cycler • For a “cyclic PRI” emitter a stable PRI is generated
for N pulses followed by another stable PRI for N pulses, etc. • For example, this cycler generates a PRI of 175 for
seven pulses and then a PRI of 150 for four pulses. 175
175
175
175
175
175
175
150
150
150
150
175
175
175
175
175
175
175
150
150
150
150
GTRI_B-50
Copyright by Georgia Tech Research Corporation, 2009
PRI Agility Jitter • For a “jitter PRI” emitter, the interpulse period
varies between every pulse usually within a known percentage range. • For example, the pulse train below is a 200 +/- 10%
jitter pulse train, i.e. the interpulse periods vary randomly between 180 and 220.
200
183
182
201
199
185
217
216
209
188
181
199
207
207
187
183
184
Copyright by Georgia Tech Research Corporation, 2009
218
203
204
200
181
GTRI_B-51
17
2/23/2009
PRI Deinterleaving Radar Signal A
Radar Signal B
Radar Signal C
Interleaved Signal
Copyright by Georgia Tech Research Corporation, 2009
Filename - 52
GTRI_B-52
PRI Deinterleaving - Sorting
Hardware Measurement
Useful for Sorting?
Frequency or Frequency Band
Yes
Time of Arrival
Yes
Angle of Arrival
Yes
Power
No
Pulse Width
Not so much
GTRI_B-53
Copyright by Georgia Tech Research Corporation, 2009
Major Signal Processing Components
Emitter Track File
Input Buffer PRI Deinterleave
Threat ID
Ambiguity Resolve
Track File Management
Copyright by Georgia Tech Research Corporation, 2009
Filename - 54
GTRI_B-54
18
2/23/2009
Threat Identification • Initial threat identification is usually a very simple
process. • The MDF assigns an initial threat ID based on
frequency/band and PRI. • So, “threat ID” is simply finding the corresponding
entry in a table in the Mission Data File. • Most initial threat IDs are ambiguous and require
ambiguity resolution. GTRI_B-55
Copyright by Georgia Tech Research Corporation, 2009
Emitter PRI Range Threat ID A B C D E F G H I J K L M N O P Q R 0
500
1000
1500 2000 2500 PRI (microseconds)
3000
3500
4000
GTRI_B-56
Copyright by Georgia Tech Research Corporation, 2009
Major Signal Processing Components
Emitter Track File
Input Buffer PRI Deinterleave
Threat ID
Ambiguity Resolve
Track File Management
Copyright by Georgia Tech Research Corporation, 2009
Filename - 57
GTRI_B-57
19
2/23/2009
Ambiguity Resolution • Initial threat ID is done based on frequency/band and
PRI. • This usually results in an ID that says “this could be either Threat
A, Threat C, Threat D, or Threat H”.
• Additional measurements are used/required to resolve
ambiguities and determine which a unique ID. • PRI agility (jitter, stagger, cycler) • Multiband • Scan type/rate • Missile guidance GTRI_B-58
Copyright by Georgia Tech Research Corporation, 2009
Major Signal Processing Components
Emitter Track File
Input Buffer PRI Deinterleave
Threat ID
Ambiguity Resolve
Track File Management
Copyright by Georgia Tech Research Corporation, 2009
Filename - 59
GTRI_B-59
Track File Management
• All RWRs have some concept of a Track File. It may
be called different names in different RWRs, but the concept is the same. • The Track File is where the OFP stores all threat
information that is has measured/computed.
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-60
20
2/23/2009
Track File Management (cont.)
• The Track File management software is almost as
complex as the PRI Deinterleaving software. • The OFP updates the track file as new information
becomes available. • There are many sources of new information:
correlation, missile guidance, angle, power, PRI agility, etc.
GTRI_B-61
Copyright by Georgia Tech Research Corporation, 2009
Track File Management (cont.) • The Emitter Track File is the most important data
maintained by the RWR OFP. • The ETF content affects operation of almost all
other OFP functions • Pilot cues (audio and display) • Initiates additional measurements for ambiguity
resolution • Alters input scheduling
• The ETF is output to other systems in an integrated
EW suite and may drive their operation as well. GTRI_B-62
Copyright by Georgia Tech Research Corporation, 2009
Simplified RWR Processing Flow
Input Buffer
RF
Signal Detection Hardware
Signal Processing
Emitter Track File
Manage Interfaces
Software
Copyright by Georgia Tech Research Corporation, 2009
Software
GTRI_B-63
21
2/23/2009
User Interface • Buttons/Lamps • CRT Display • Audio • Missile launch • New guy • Diamond
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-64
Interface Management
• Besides the user interface the OFP also manages
other intrasystem and intersystem input/output. • Intrasystem: Setting up pulse collection hardware,
messaging on intrasystem hardware interfaces, messaging between OFPs within the RWR, etc. • Intersystem: MIL-STD-1553B data bus (EW Bus and
Avionics Bus), blanking interface, etc.
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-65
RWR “Challenges” • There are many challenges to accurately and
effectively operating an RWR in a real-world environment: • High pulse densities • Interference from other onboard systems • Aircraft maneuvers • Urban noise • Antenna patterns Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-66
22
2/23/2009
ALR-69 System Block Diagram CVR SUBSYSTEM
CVR 135 AM-423 45
CVR 45
J1
J1
E, G, I (135)
AM-423 135
J3
J2 J3
CVR 225
CVR 315
J1
AM-423 225
AS-3305 (45) (135) (Omni) (315) (225)
CM-479
E, G, I (45)
J2
E, G, I (225)
E, G, I (315)
ALQ-213 CMSP IP1310 F1
2X 2Y J1
J3
J1 F2
J4
J2
Diamond Audio
J2
J2
J3
J3
E, G, I Band Video (45, 135, 225, 315) C/D Band Video (45, 135, 225, 315) Omni Video
AM-423 315 AM-6971
J1 J2 J5 J4 J3
J6
J3
J1
J5
HSDB J4
J2 N1
J7
ANT7
C/D, E, G, I Band Static Video (TTL)
FSRS Subsystem AM-423 135 (FSRS)
J2
AM-423 45 (FSRS)
J1
F1 F2
J3
J3 J4
J1 J5
J2
J3
AM-423 315 (FSRS)
F3
R-2094 J1
J6
AM-423 225 (FSRS)
C-10373
Antenna Control (0-3)
SA-2263
J5
J2
J4
RI/D, Control (0-3), CW Strobe, PRF Window Rec. Int., Discrimn. Video, Bandpass Video GTRI_B-67
Copyright by Georgia Tech Research Corporation, 2009
The Travels of “Joe Pulse” RF
RF cable
Input Buffer
Process Buffer Pre-Process (PRE_PROC)
A6 RAM
ETF Record ETF
A6 RAM
A6 OFP Display Update
Display File A4 RAM
Pre-amp
Antenna Air
Pulse packet
Video pulse
RF
Input Buffer
AM-6639
J1
J2
PRI Deinterleave (PRIDE)
A4 OFP Display Update
Quadrant video signals
PRIDE Outputs A6OFP variables
Refresh Buffer A4 RAM
Video Processor (A5 CCA)
Emitter ID (EIDR)
Display Refresh
DMA FIFO
Threat ID A6OFP variables CRT Drive H/W
A6 RAM
ETF Mgt (ETE)
ETF Record ETF
IP-1310
I/O
Copyright by Georgia Tech Research Corporation, 2009
GTRI_B-68
23
View more...
Comments
