krzysztof kulpa, passive radar warsaw university of technology institute of electronic systems...

Krzysztof Kulpa, Passive radar

Warsaw University of Technology

Institute of Electronic Systems

POLAND Radar Symposium 2014 , KACST, Riyadh Saudi Arabia, 9-10 December 2014

Passive Radar

Krzysztof Kulpa

Professor Scientific Director

Defense and Security Research Center

Institute of Electronic SystemsWarsaw University of Technology

Nowoiejska 15/1900-665 Warsaw, Poland

e-mail: [email protected]





1. Introduction to Passive Multistatic Radars

2. Array antenna

3. Direct signal and clutter cancelation

4. Detection

5. Tracking

6. Applications

Introduction Coverage Design Antennas Clutter CLEAN Tracking WUT PaRaDe Conclusions

Outline Tx

Rx






WUT is the largest of 18

Polish technical

universities

Public state school







19 facultiesOver 30 thousand students

~2500 academic staff






WUT Radar Technology LabRadar Modeling, Signal Processing, Applications

• Passive radar• Noise radar• FMCW radars• Maritime radars• ATC• micro-Doppler• NCTR• THZ active imaging• Active radars (inc. MIMO)• Electronically Scanned Antenna• T/R modules control and calibration• SAR radars (X, W bands 15 m -> 5 cm res.)• ISAR (ships, planes, ground targets)• Radar signal simulations• ECM/ECCM inc. DRFM

Cooperation with:• radar industry

PITRADWAR• Polish Army• EDA• NATO STO• International labs





Active radar detection

Mono-staticsite

Bi-static site

Moving target

Emission(illumination)

Echo return

Bi-static Echo

return

Advantage:• Mature technology • Reliable• Independent

Disadvantage:• Target warning • High power consumption• Limited accuracy • Low Pd for low RCS targets






Angle/time estimation sites

Moving target

On board Man-made EmissionAdvantage:

• Mature technology • High Accuracy• Covertness

Processing Site

Data Link

DOA or TDOA

Disadvantage:• Requires target man-made

emissions • High bandwidth data links

needed








Passive Coherent Localization

Advantage:• No dedicated transmitters • Covert • High Accuracy• No warning of target

Different illuminators

Mono- or multi-static receivers

NOT PASSIVE !!!

Disadvantage:• Not mature technology• High computational power• High complexity of algorithms• Not fully reliable• Required illuminators of

opportunity Data LinkProcessing Site






Signal processing and Visualisation using oscilloscope Detection range: 8 miles !

Illuminator of opportunity: BBC - Empire Radio Station, 10 kW, wavelength 49m

26 February 1935 Arnold Wilkins (operator), A. P. Rowe & Robert Watson Watt.

Daventry Experiment

Introduction Coverage Sognals Antennas Clutter CLEAN Tracking WUT PaRaDe Conclusions





First operational passive radarGermany (1943)

C

C CC CC

C

Illuminator:Chain Home radar (GB)

ReceiverantennaFrance

Target

Klein Heidelberg






PCL Radar principles

o

iAOTTRT kTND

tSSGPrr

2)4( Bi-static detection range

TransmitterReceiver

Target

i

o

RT

AOTT

t

kTND

rr

SSGP

222)4( Bi-static detection equation

rTrR

i Tt

tc

vFj

bTR dte

c

rtXtXvry

0

4* )2()(),(

Detection: Cross-ambiguity function (matched filtering)

tc

vFj

TR

t

ec

rtAXttX

4)2()()(

Received signalIntroduction Coverage Sognals Antennas Clutter CLEAN Tracking WUT PaRaDe Conclusions

rB

rB= rR + rT - rB





42)4( o

iAOTT

kTND

tSSGPr

PCL Detection range

FM

TV

DAB/DVB-T

GSM/GPRS

WIMAX/LAN

Wi-Fi

Air surveillance (long range)

Urban operations






FM Signal spectrum






FM Signal ambiguity






DVB-T Signal spectrum






DVB-T Signal ambiguity






GSM Signal spectrum






GSM Signal ambiguity






PCL Scenario

Target echo

Reference antenna

Main antenna

Transmitting antenna

Reference signal

Ideal case






receiver

transmitter

[km]

[km

]

Detection RCS (theoretical) [dBsm]

-200 -150 -100 -50 0 50 100 150 200-200

-150

-100

-50

0

50

100

150

200

-20

-15

-10

-5

0

5

10

i

o

RT

AOTT

t

kTND

rr

SSGP

222)4( Bi-static detection rangeP = 10 kW

Coverage prediction

Introduction Coverage Signals Antennas Clutter CLEAN Tracking WUT PaRaDe Conclusions

Fighter

Airliner

Missile





Array Antenna 8 element FM circular array antenna

3 directional TV antennas






Digital beamforming

dB

degLin - polar

8 element FM circular array antenna8 x λ/2 dipoles

Rectangular window12 dB gain, -7dB sidelobes






Digital beamforming

dB

Lin - polar

8 element FM circular array antenna8 x λ/2 dipolesC windows set

11 dB gain, -28 sidelobes

deg






Digital beamforming 8 element FM circular array antenna

8 x λ/2 dipolesMulti-beam beamforming 8 beams, -3dB crossing






Digital beamforming 8 element FM circular array antenna

8 x λ/2 dipolesMulti-beam beamforming 16 beams, -1dB crossing






PCL Scenario

Target echo

Reference antenna

Main antenna


Reference signal

Direct signal

Direct signalIntroduction Coverage Design Antennas Clutter CLEAN Tracking WUT PaRaDe Conclusions





PCL Scenario

Target echo

Direct signal

Reference antenna

Ground Clutter

Reference signal

Main antenna


Direct signal +clutter






PCL Scenario

Target echo

Direct signal

Reference antenna

Ground Clutter

Reference signal

IndirectReference signal(multipath)

Main antenna


Direct signal +Clutter + multipatch and targets inReference signal






Bistatic Measurements

Targets

Range-Doppler correlation results Dynamic 120 dB

• Long observation time (~1s)• Low/medium range resolution• No angle resolution• High Doppler resolution• Measurement of R, V [,a]• different illuminators

of opportunity: FM, DAB,DBVT, GSM, WiMax and others






TransmitterReceiver

Target1

Short range target signal masking effects – multiple targets

Strong echo return can be assumed as a noise signal while detecting long-range targets

rTrR

Target2

Correlation based detection is optimal only for single target case

M

i

tc

vFj

iTiR

it

ec

rtXAttX

1

4)2()()(

Masking effect






Direct power24 T

OTT

r

SGPp

Pt=10kW

Pt=1MW

Direct power

P = 100 kWR = 10 kmp = -11 dBmkTB = -121 dBmpt = -146 dBm

Required dynamicRangeto noise = 110 dBto target = 135 dB

Correlation gain 40-60 dB (only)

70-100 dB direct signal and clutter cancelation is required






Final coverage

[km]

[km

]

Detection RCS - near target suppresed [dBsm]

receiver

transmitter

-200 -150 -100 -50 0 50 100 150 200-200

-150

-100

-50

0

50

100

150

200

-20

-15

-10

-5

0

5

10






Strong signal masking effectNear range strong signal can be treated as an additional noise during long-range target detection

To decrease long-range target detection loses strong target echo removal procedures must be apply

10-3 10-2 10 -1 1000

10

20

30

40

50

60

near/far range ratio

dete

ctio

n lo

ses

[dB

]Introduction Coverage Design Antennas Clutter CLEAN Tracking WUT PaRaDe Conclusions





Short distance target masking effect

Short distance strong echo masking effect

Solution:

Adaptive clutter/targets removal

Requirements:

Good channels match

reference and main, low multi-path effects

[km]

[km

]

Detection RCS - near target blinding effect [dBsm]

receiver

transmitter

target

-200 -150 -100 -50 0 50 100 150 200-200

-150

-100

-50

0

50

100

150

200

-20

-15

-10

-5

0

5

10

dBsm






Strong echo removal procedureCLEAN

STEP I - Strong echo estimation using maximum of range-Doppler correlation function

i Tt

tc

vFj

bTR dte

c

rtXtXvry

0

4* )2()(),(

STEP II - Strong echo removal t

c

vFj

TRR

t

ec

rtXAtXtX

1̂41

1)1( )

ˆ2(ˆ)()(

STEP III – long-range echo estimation using maximum of range-Doppler correlation function

i Tt

tc

vFj

bTR dte

c

rtXtXvry

0

4* )2()(),(

STEP IV – test: if strongest echo > limits -> continuation of strong echo removal

( go to STEP II )






Strong echo removal effectDirect signal masking effects and short distance strong echo masking effect taken into consideration

Direct signal antenna base suppression

[km]

[km

]

Detection RCS - near target suppresed [dBsm]

receiver

transmitter

target

-200 -150 -100 -50 0 50 100 150 200-200

-150

-100

-50

0

50

100

150

200

-20

-15

-10

-5

0

5

10






Reference channel problems

Main antenna

Reference antenna

Reference receiver

Main receiver

DSPPCL processor

Reference signal


Refrence and Main Receiver response characteristic difference Multipath in reference channel


f

|A|





Why good reference channel is required

Low target side-lobes Good attenuation of direct signal Good attenuation of ground clutter Adaptive removal of strong targets






Reference channel equalization methods

Knowledge based equalization methods Constant amplitude method Methods based on signal structure Digital signal reconstruction Indirect path knowledge base

Environment-based method Ground clutter based equalization

DSP-based method Maximum contrast methods Reference point equalization






Reference channel signal restoration

A/CDigital

decoderDigital coder

Restored signal

For digital modulation (GSM, WiFi, DAB, DVBT) it is possible to restore original signal by:

• decoding the bit-stream• apply the bit-error correction• encode






Single-antenna system

A/CDigital

decoderDigital coder

Restored signal

Clutter cancelation

Range-Doppler

Correlation

Plot extraction






PCL localization

xmeas1(t)

xmeas2(t)

Single Transmitter/Receiver pairRange/Angle estimation

Poor cross-range resolution

Multi Transmitter/Receiver pairRange/Angle estimation +

Ellipsoid cross-section estimationGood range & cross-range resolution

For good performance several transmitters are needed

Increase of sensitivity due to multistatic operation

Bistatic

MultistaticIntroduction Coverage Design Antennas Clutter CLEAN Tracking WUT PaRaDe Conclusions





PCL localization Multistatic


Single receiver

• blind zone possible• zones of low Doppler or range resolution• zones with reduced visibility towards the transmitters• possibility of ghost targets Ghost

targets

Blind zones





PCL localization MultistaticMulti receiver


• Reduced blind zones• High probability of detection/tracking• Data exchange required





Tracking

Combining bistatic measurements from different TxRx pairs

Calculating Cartesian coordinates of plots

TrackingPlot-track association

Kalman filtering

Bistatic trackingPlot-track association

Kalman filtering

Cartesian TrackingExtended Kalman filtering

Trackverification

Single-stage tracker Two-stage tracker






Cartesian Tracking

Combining bistatic tracks from different TxRx pairs

Time aligment

Calculating Cartesian coordinates of tracks

Track fusion (for NTxRx>3)

Cartesian TrackingExtended Kalman filtering

Trackverification

Bistatic TracksBistatic Plots

Bistatic Trackers






Parallel updating

k

k

k

k

b

b

b

3

2

1

z

z

z

z

k

k

k

k3

2

1

H

H

H

H

• Extended Kalman filtering• High dimension of measurement matrices• Bistatic tracking –

for primary plot selection• If missing plot in single TxRx pair –

Kalman prediction used instead of plot • For asynchronous measurements - interpolation • Filter equations dependant on the number

of TxRx pairs


All ellipsoids





Serial updating

• Extended Kalman filtering• Constant dimensionality (low)• Bistatic tracking –

for primary plot selection• If missing plot in single TxRx pair –

no action is taken • ready for asynchronous measurements• comparable computational power

switch


one ellipsoid a time





ResultsScenario:Rx - 1Tx - 3Targets - 3






WUT PaRaDe PCL demonstrator Correlator display

Track display

Plot displayFM radio as illuminator of opportunity






PARADE






PARADEReal time processing

Plot displayTrack displayIntroduction

Coverage Design Antennas Clutter CLEAN Tracking WUT PaRaDe Conclusions






PARADELong range tracking: 600-80 km bistatic

Bistatic display XY display





Mobile PaRaDe (2007)

R T(t)

L(t)

Direct signal and clutter

Transmitter of

opportunity

PCL system on moving platform

RS (t)

R S(t)

RT (t)

Target

Clutter

PCL platform






Airborne PaRaDe (2008)

[km]

[km

]

Detection RCS - [dBsm]

-200 -100 0 100 200 300 400 500

-250

-200

-150

-100

-50

0

50

100

150

200

-30

-25

-20

-15

-10

-5

0

5

10

Detected target

First trials

Multistatic coverage

AntennasHardware Data fusion

STAP processing






PET-PCL


PIT-RADWAR POLAND

GUNICA PCL

PCL-PET 4 mobile radar setArea: 40x40 km





Passive detection based on active radar illumination






Passive radar features (1)• High update rate

• FM 1s• DVB-T 0.1 s• GSM 0.3 s• SAT-TV 0.1-0.3 s

• High detection range • FM 800 km bistatic • DVB-T 400 km bistatic• GSM 40 km bistatic

• No own emission (ARM missile - not a danger)

• Possible of exploitation pulse (radar) emitters

• Possible of exploitation of over-horizon far transmitters

(up to 400 km range)






Passive radar features (2)• Continues illumination on target

• no range/Doppler ambiguity

• no blind speeds/ranges

• NCTR capabilities

• ISAR imaging

• micro-Doppler analysis

• detection of rotor flashes

• engine modulation detection






Passive radar features (3)• Detection coverage increase by:

• netted PCL radars

• data fusion on track level (classical)

• data fusion on bistatic track level

• data fusion on plot level

• data fusion on raw data level

• Data link requirements

• high data throughput – especially for raw data level fusion

• Time synchronization requirements

• track/plot level - 1 ms

• data level – 10 ns + frequency and phase coherency






Passive radar features (4)• Detection of low RCS targets:

• stealth targets

• drones /UAV

• missiles

• Detection of target behavior

• acceleration measurement

• target split

• shape changes






Passive radar features (5)• Multiband operation:

• FM radio (88-108 MHz)

• DAB (~200 MHz)

• DVB-T (450-850 MHz)

• GSM, LTE ..: 850, 950, 1800, 2100 and others

• DVB-S (C, X Ku band)

• Satellite radio (C band)

• Active radar exploitation

• VHF/UHF radar

• L band radars (including SSR)

• C band radars (including weather radars)

• S band radars






Passive radar features (6)• ECM resistant:

• wide bandwidth

• lack on knowledge where is (are) receivers

• high power jammer may be used as illuminator

• Jammer tracking

• DOA

• TDOA (high accuracy)

• No transmitter case

• Add own FM/DVB-T transmitter

• Add high power jammers (NOISE RADAR !)

• Relay on neighbors transmitters (up to 400 km range)






Mobile systems

Airborne sensors

Future of PCL

Personal sensors

Fixed systems

Maritime sensors






Future conferences in POLAND


SPS-2015

Signal Processing Symposium

10-12 June 2015

Poland, Warsaw/Debe

Important DatesPapers for reviewing (3 - 4 pages): February 10, 2015 Notification for Authors: March 10, 2015Early participants R registration: April 01, 2015 Full paper submission: April 21, 2015 SPS 2015: June 10-12, 2015

Radar, remote sensingBiomedical signal processingImage processingSecurity http://sps2015.ise.pw.edu.pl





Future conferences in POLAND


IRS 2016 17th International Radar Symposium

May 10-12, 2016Krakow, PolandChaired by: Krzysztof Kulpa Hermann Rohling

http://mrw2016.org/en/irs2016/about-irs

mrw2016.org





Thank you


krzysztof kulpa, passive radar warsaw university of technology institute of electronic systems...

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