bistatic and multistatic radar - semantic scholar › 3f61 › fe08e00103aa...willis, n.j.,...

Hugh Griffiths

THALES / Royal Academy of Engineering Chair of RF Sensors

University College London

President, IEEE Aerospace and Electronic Systems Society

Bistatic and Multistatic Radar

IEEE AESS Distinguished Lecture, ETH Zurich, 7 November 2013.

• A bit of history

• Bistatic radar fundamentals

• A bit more history

• Bistatic radar clutter

• Passive Bistatic Radar …

2

Outline

The first radar – Hülsmeyer, 1904

3

The first radar – Hülsmeyer, 1904

4

Painting by Roy Huxley

The Daventry Experiment: 26 February 1935

5

Neale, B.T., ‘CH – the First Operational Radar’, GEC Journal of Research, Vol. 3 No.2

pp73-83, 1985.

CHAIN HOME

6

• The Chain Home radar has been described as a ‘dead-end design’, but as a

system to deliver an air defence capability it was certainly very effective.

• There were four (later reduced to three) metal transmitter towers in a line,

and four wooden receiver towers arranged in a rhomboid pattern. The

transmitter produced floodlight illumination of approximately 100°

beamwidth from a ‘curtain’ of eight horizontally-polarised half-wave dipoles,

each with a tuned reflector element 0.18λ behind. The curtain included a

main array above a secondary ‘gapfiller’ array of four dipoles. The stations

could be tuned to four different bands in the range 20 MHz to 30 MHz. The

operator could switch between the two arrays as needed. The output stage

of the transmitters used special water-cooled tetrode valves built by

Metropolitan Vickers.

• The wooden towers for the receiving arrays were shorter, about 76 m tall.

Each wooden receiving tower initially featured three receiving antennas, in

the form of two dipoles arranged in a cross configuration, spaced up the

tower. Additional crossed dipoles would be fitted later in the War to deal with

German jamming.

Greg Goebel, The Wizard War: WW2 and the Origins of Radar, http://www.vectorsite.net/ttwiz.html

CHAIN HOME

7

In the autumn of 1922, A.H. Taylor and L.C. Young of the Naval Research

Laboratory in the USA demonstrated detection of a wooden ship using a CW

wave-interference radar, at a wavelength of 5 m.

In December 1924, Appleton and Barnett in the UK used an FM radar technique to

measure the height of the ionosphere, and the following year Breit and Tuve in the

USA used a pulsed radar for the same purpose.

The first detection of aircraft using the wave-interference effect was made in 1930

by L.A. Hyland of the Naval Research Laboratory in the USA.

More history …

8

Appleton, E.V. and Barnett, M.A.F., ‘On some direct evidence for downward atmospheric reflection of

electric rays’, Proc. Roy. Soc., Vol.109, pp261-641, December 1925. (experiments at end of 1924)

ionosphere

transmitter

(Bournemouth)

receiver

(Oxford)

h

d

r

2

r dt

c

2 2 2

2

c t ctdh

The first FMCW radar

9

Freya,

Wassermann,

Mammut,

Jagdschloss –

early warning

Würzburg – fighter

control

Lichtenstein

SN2 – AI

German air defence radars

Bistatic radar - taxonomy

11

Bistatic radar

• bistatic radar has potential advantages in detection of targets which

are shaped to scatter energy in directions away from the

monostatic;

• the receiver is covert and therefore safer in many situations;

• countermeasures are difficult to deploy against bistatic radar;

• increasing use of systems based on autonomous air vehicles

(UAVs) makes bistatic systems attractive, since bistatic operation

may remove the need for a relatively small UAV to carry the heavy,

complex and power-hungry transmitter;

• many of the synchronisation and geolocation problems that were

previously very difficult are now readily soluble using GPS, and

• the extra degrees of freedom may make it easier to extract

information from bistatic clutter for remote sensing applications. 12

F-117A

13

TR

RR

transmitter receiver

Jackson, M.C., ‘The geometry of bistatic radar systems’; IEE Proc., Vol.133, Pt.F, No.7, pp604-612,

December 1986.

T

target

L

2 2

2 sin

T R

R

T R R

R R LR

R R L

2

baseline

extended

baseline

R

N

isorange contour

(ellipse)

T R

14

Bistatic radar geometry

Contours of constant bistatic range are ellipses, with the transmitter

and receiver as the two focal points

TR RR

+ = constT RR R

L = bistatic baseline


target

Targets lying on the transmitter-receiver baseline have zero bistatic range. 15

Bistatic radar geometry

This is derived in the same way as the monostatic radar equation :

The dynamic range of signals to be handled is reduced, because of the

defined minimum range.

TR RR

b

TG RG

2

2 2

0

2

3 2 2

0

1 1 . . . . .

4 4 4

4

R T T Rb p

N T R

T T R b p

T R

P P G GL

P R R kT BF

P G G L

R R kT BF

Bistatic radar equation

16

TP


Jackson, M.C., ‘The geometry of bistatic radar systems’; IEE Proc., Vol.133, Pt.F, No.7, pp604-612,

December 1986.

target

2

L

Rv

Tv

v

T

R

T

T R

Bistatic radar Doppler

17

2cos cos 2D

Vf For VT = VR = 0 ; V ≠ 0

special cases :

0

0

180

0

90

2

0,180

90 2

2 cos

Df

v

condition

monostatic

monostatic

forward scatter

v to bisector

v tx or rx

v bisector

v to tx or rx LOS

2v

0

0

22 cos 2v

2 cos 2v

sinv

Willis, N.J., ‘Bistatic radars and their third resurgence: passive coherent location’, IEEE Radar

Conference, Long Beach, USA, April 2002.

Bistatic radar Doppler

18

COMPLEX

TARGETS:

Assembly of discrete

scattering centers

Flat plates

Corner reflectors

Dihedrals

Resonant cavities

Ewell, G.W. and Zehner, S.P., ‘Bistatic radar cross section of ship targets’, IEEE J. Oceanic Engineering,

Vol.OE-5, No.4, pp211-215, October 1980.

Bistatic/Monostatic RCS ratios

for 4 small freighters

X-band, grazing incidence

19

Babinet’s principle tells us that we get exactly the same scattering from a

perfectly-absorbing target as we would from a target-shaped hole in an

infinite perfectly-conducting sheet !

0

20

Forward scatter

2

2

4b

A

(radians)B

d 2( )b

dBmB

10log f

30 MHz 100 MHz 300 MHz 1 GHz 3 GHz 10 GHz

20º

10º

0º

+60

+50

+40

+30

21

Forward scatter

Klein Heidelberg

22 Griffiths, H.D. and Willis, N.J., ‘Klein Heidelberg – the first modern bistatic radar system’, IEEE Trans.

Aerospace and Electronic Systems, Vol.46, No.4, pp1571–1588, October 2010.

Stellung BIBER

(Netherlands)

Stellung TAUSENDFÜSSLER

(Cherbourg)

Klein Heidelberg

23

picture © Jeroen Rijpsma

Klein Heidelberg

24

Klein Heidelberg

x

x

x

x

x x

Klein Heidelberg

BIBER

BIBER (Oostvoorne)

(Stellung BIBER, Oostvoorne) 30

Klein Heidelberg

L480 Bunker (Stellung BIBER, Oostvoorne)

Klein Heidelberg

31

Willis, N.J., ‘Bistatic Radar’, chapter 25 in Radar Handbook, second edition, (M.I. Skolnik ed.),

McGraw-Hill., 1990.

• All of the parameters

associated with

monostatic clutter –

plus geometry

• Little data exists

• Maximum at specular

reflection (‘specular

ridge’) and at forward

scatter

Bistatic radar clutter

32

Adapted from Willis, N.J., ‘Clutter’, chapter 9 in Bistatic Radar, Artech House, 1991

organization authors surface frequency polarization i s f

Ohio State

University

(1965)

Cost,

Peakes

smooth sand, loam,

soybeans; rough sand,

loam with stubble, grass

10 GHz VV, HH

HV

5 – 30˚

10 – 70˚

5 – 70˚

5 – 30˚

5 – 90˚

5 – 90˚

0 – 145˚

0, 180˚

0, 180˚

Johns Hopkins

University

(1966-67)

Pidgeon sea (sea states 1, 2, 3)

sea (Beaufort wind 5)

C-band,

X-band

VV, VH

HH

0.2 – 3˚

1 – 8˚

10 – 90˚

12 – 45˚

180˚

180˚

GEC Stanmore

(1967)

Domville rural land, urban land,

sea (20 kt wind)

X-band VV, HH 6 – 90˚

≈ 0 – 90˚

6 – 180˚

≈ 0 – 180˚

180, 165˚

180, 165˚

University of

Michigan

(ERIM) (1978)

Larson,

Heimiller

semidesert, grass with

cement taxiway, weeds

and scrub trees

1.3 and

9.4 GHz

HH, HV ≈ 0

10, 40˚

10, 15, 20 ˚

?

5, 10, 20˚

180, 165˚

0 – 180˚

0 – 105˚

Georgia

Institute of

Technology

(1982-84)

Ewell,

Zehner

sea (0.9, 1.2 – 1.8 m

wave heights)

9.38 GHz VV, HH ≈ 0 ≈ 0 90 – 160˚

University of

Michigan

(EECS) (1988)

Ulaby et

al.

smooth sand

rough sand

gravel

35 GHz

VV, HH

VH, HV

24˚

30˚

30˚

24˚

30˚

10 – 90˚

0 – 170˚

0 – 170˚

0 – 90˚

33


Domville, A.R., ‘The bistatic reflection from land and sea of X-band radio waves’, GEC (Electronics) Ltd.,

Memo SLM 1802, Stanmore, England, July 1967.

In-plane, X-band

sea, horizontal

polarisation,

wind speed 20

knots

1 = 2 (monostatic)

grazing

incidence

normal

incidence

grazing

incidence

2 = 180 – 1 (specular)

34


Bistatic angle ~50°

Yates, G.A., ‘Bistatic Synthetic Aperture Radar’, PhD thesis, University College London, January 2005.

Bistatic SAR image

35

Monostatic Bistatic

(~70°)

Yates, G.A., ‘Bistatic Synthetic Aperture Radar’, PhD thesis, University College London, January 2005. 36

Comparison of monostatic and

bistatic SAR image

It might be expected that bistatic clutter should be less ‘spiky’ since dihedral

and trihedral reflectors will not give strong reflections in bistatic geometries.

Very little experimental data exists – but results from bistatic imagery of urban

target scene show higher values of K-distribution shape parameter n for

bistatic geometry.

Yates, G.A., ‘Bistatic Synthetic Aperture Radar’, PhD thesis, University College London, January 2005.

monostatic bistatic

fit n fit n

field 1 16% 4.27 80% 10.01

field 2 72% 6.02 58% 6.25

field 3 46% 4.10 44% 5.64

37


Carrier frequency 2.4 GHz

Peak transmitted power +23 dBm

Maximum range over which data is

recorded 3000 m

Antenna beamwidth 8º × 8º

Maximum bandwidth 50 MHz

Nominal range resolution 3 m

Pulse lengths 0.1 – 10 µs

Available transmissions Chirp, Barker code, Pulse, Polyphase /

Deng codes, Passive, Continuous

PRF 50 Hz – 3 kHz

Maximum number of pulses 1500

The current radar network consists of three nodes where two nodes are connected to a

central node with 50 m network cables.

A 100 MHz reference oscillator is also distributed to all three nodes via three 50 m cables.

The user interface to the system is by a PC connected via parallel port to the DSP card.

When outdoors, the system is powered by 65 Ah lead-acid battery.

38

NetRAD – a multistatic radar system

• September / October 2010, with support from ONR

Global, THALES UK and THALES NL

• In the Cape area of South Africa, in collaboration with

the University of Cape Town and CSIR

• Preceded by trials in the UK to prove correct operation

of the system and to gain experience

• A range of experimental parameters.

Bistatic clutter trials

39

40

Why South Africa ?

41

Bistatic clutter trials, Cape Point

Bistatic clutter trials, Cape Point

42

transmitter/

receiver

receiver

Bistatic clutter trials, Scarborough

Parameter Monostatic Node Bistatic Node

Carrier Frequency 2.4 GHz 2.4 GHz

Nominal Bandwidth 50 MHz 50 MHz

Beamwidth 9° (az) × 11° (el) 9° (az) × 11° (el)

Height above sea level 12 m 10 m

Rx losses and Noise Figure 7.7 dB 5.4 dB

Tx losses 2 dB -

Transmitted Power 500 W -

PRF 1 kHz -

• significant wave height 1.3 m

• swell propagating towards shore,

• sea state 2/3

• wind speed approximately 4 ms1

from a southerly direction.

1

0

expexpC N

n n

bxb x IP I dx

x p x p

n n

n

K+noise distribution:

V-pol clutter measurements, 5 October 2010

46


47

RM m β σ0M dB m2/m2 σ0

B dB m2/m2 CNRM dB CNRB dB nM nB

805 30° 59.2 58.7 18.1 21.5 0.93 3.11

417 60° 47.1 47.6 36.9 40.2 0.22 0.48

295 90° 44.1 55.8 41.1 35.6 0.17 1.04


48

clutter+noise

T

FA

V

P p R dR

p(R)

V T

monostatic

p(R)

V T

bistatic

R

R

A CFAR algorithm will set a

detection threshold to give a

particular value of PFA on the basis

of clutter+noise.

If the pdf of clutter+noise is shorter-

tailed, the detection threshold for a

given value of PFA will be lower.

Impact on detection performance

49

Bistatic target measurements: Simon’s Town (ii) Bistatic target measurements: Simon’s Town

transmitter/

receiver

receiver

50

Bistatic intensity plot and Doppler signature of a RHIB making two concentric circles. Bistatic angle~6o.

Target bistatic signatures

51

Time (s)

Do

pp

ler

(Hz)

Time-Varying Doppler Signature

0 20 40 60 80 100 120 -500

-400

-300

-200

-100

0

100

200

300

400

500

e10_10_16_1800_40_P1_1_130000_S0_1_2047_node3 - Node 3 Rx

RHIB target making circling manoeuvre 52

Target bistatic signatures

• NetRAD is a unique and highly flexible sensor which allows

measurements of bistatic radar clutter, bistatic target signatures and

experiments with networked radar

• Two sets of simultaneous measurements of monostatic and bistatic

sea clutter have shown that the shape parameter n of the K-distribution

is higher for the bistatic clutter – i.e. that the bistatic clutter is less

spiky.

• This may have important implications for the detection of small targets

against sea clutter

• Interesting measurements of bistatic signatures of maritime targets and

their wakes

• Lots more data, and lots more to do to analyse and understand …

Summary

53

In general, bistatic radar systems will use dedicated radar transmitters with explicit control

over location, modulation, scan pattern, etc.

However, it is also possible to use other transmissions that just happen to be there. These

are known as illuminators of opportunity, and the technique is sometimes known as

passive bistatic radar (PBR), hitchhiking, parasitic radar or passive coherent location

(PCL)

Such transmissions may be other radars, or they may be communications, broadcast or

navigation signals. In these days of spectral congestion there are more and more such

transmissions, and they are often high-power and favourably sited.

They also allow use of parts of the spectrum (VHF, UHF, …) that are not normally available

for radar purposes – where there may be a counter-stealth advantage (in addition to the

potential counter-stealth advantage that comes from the bistatic geometry)

As well as that, no transmitting licence is needed

And the radar is potentially completely covert, so countermeasures against it may be very

difficult

Passive Bistatic Radar (PBR)

54

• plenty – for ATC, long range air defence, AEW, etc.

• in general will scan in azimuth – hence synchronization and pulse

chasing necessary

• waveform and F very favourable

Existing radars (terrestrial, naval, airborne ... )

55

• VHF (~100 MHz), bandwidth ~50 kHz (c/2B = 3000 m); typically 4

channels per transmitter covering 10 MHz total

• broadband FM

• highest power transmitters in UK are 250 kW EIRP; many others of

lower power

• 250 kW EIRP gives F = 57 dBW/m2 @ 100 km

• omnidirectional in azimuth; vertical-plane radiation pattern shaped to

avoid wasting power above horizontal

http://www.bbc.co.uk/reception/

FM radio

56

FM radio

UCL ENGINEERING

Change the world

• BBC Radio 4, 93.5 MHz,

Wrotham (Kent)

• aircraft target on approach to

Heathrow, crossing baseline

• receiver located so that direct

signal is weak, hence beat

between direct signal and

Doppler-shifted echo has

maximum modulation

• Doppler shift goes through

zero as target crosses

baseline

Heathrow

airport

VHF FM

transmitter

Wrotham

93.5 MHz

bistatic receiver

50 km

58

Forward scatter VHF FM

• UHF (~550 MHz), bandwidth of video modulation ~5.5 MHz

• highest power transmitters in UK are 1 MW EIRP; many others of

lower power

Emley Moor is the tallest television mast

in England. It has a height of 330 metres

and weighs 11,000 tonnes. Picture courtesy of Dr Stuart Anderson, DSTO

Terrestrial analogue TV

59


60

vision

carrier chrominance

subcarrier

analog

sound

carrier

2MHz/div

digital

sound

carrier

vestigial-sideband

amplitude modulation

digital

TV channel

6 MHz

6.225 MHz

8 MHz

0 7 -1.25

measured spectrum of

analogue (and digital) TV

signals

In the UK the PAL (Phase Alternating

Line) modulation format is used, in which

the video information is coded as two

interlaced scans of a total of 625 lines at

a frame rate of 50 Hz. The start of each

line is marked with a sync pulse, and the

total duration of each line is 64 ms. The

video information is modulation onto a

carrier as vestigial-sideband AM, coded

as luminance (Red + Green + Blue) and

two chrominance signals (Green – Blue)

and (Red – Blue). The two chrominance

subcarriers are in phase quadrature, so

that they can be separately recovered.

The sound information (including stereo

information) is frequency-modulated onto

a second carrier.


61

http://www.sitefinder.radio.gov.uk

Cellphone basestations

62

• each consists of a network of 24

satellites; orbit height ~20,000 km

• both systems L-band (1200 – 1600

MHz)

• GPS is CDMA, GLONASS is FDMA

• bandwidths between 1 MHz and 10

MHz

• F = 134 dBW/m2 on ground

• timing and synchronisation not a

problem !

• claimed 60 – 70 dB processing gain

(1 Hz b/w)

He, X., Cherniakov, M. and Zeng, T., ‘Signal detectability in SS-BSAR with GNSS non-cooperative transmitters’; Special

Issue of IEE Proc. Radar, Sonar and Navigation on Passive Radar Systems, Vol.152, No.3, pp124–132, June 2005. 63

GPS / GLONASS / GALILEO

WiFi and WiMAX

64

WiFi WiMAX

K. Chetty, K. Woodbridge, Guo, Hui and G.E. Smith, ‘Passive bistatic WiMAX radar for marine surveillance’, Proc. IEEE

International Radar Conference RADAR 2010, Washington DC, 10–14 May 2010.

Guo, Hui, S. Coetzee, D. Mason, K. Woodbridge and C.J. Baker, ‘Passive radar detection using wireless networks’, Proc.

IET International Radar Conference RADAR 2007, Edinburgh, pp1–4, September 2007.

F (dBW/m2)

-50

-60

-70

-80

-90

-100

-110

-120

-130

-140

terrestrial TV @ 100 km

FM radio @ 100 km ENVISAT ASAR

satellite RA

cellphone basestation @ 10km

satellite DBS TV

satcoms

GPS / GLONASS / GALILEO

calculated on the

basis of a single

channel, free space

propagation, whole

signal, no processing

gain

WiFi @ 100 m

WiMAX @ 10 km

65

Comparison of power densities

85 dB

–50

–60

–70

–80

–90

–100

–110

–120

Pn = kT0BF = –122 dBm in B = 50 kHz 95 MHz 100 MHz

–40

–50

–60

–70

–80

–90

–100

–110

95 MHz 100 MHz

Noise levels in a passive radar receiver in FM radio band: (i) thermal noise in 50 kHz

bandwidth corresponding to 5 dB receiver noise figure; top of screen = –50 dBm (ii) signal

and noise levels measured from 10th floor of UCL in Central London on vertically-polarised

dipole antenna; top of screen = –40 dBm.

Noise level

66

FM Transmitter

Rx Tx

67

• 50 km from

receiver

• Height 375 m

• ERP 50 kW

• 96.8 MHz

• V-pol.

FM Radio Bistatic Radar

• Installed May 2002

$20 Reference Antenna

Surveillance Antenna

Digital V/UHF Receivers

68

Example Tracks

(4 second update rate using 1 PC)

150km

Phase interferometry used to estimate bearing – still needs calibration

69

70

Lockheed Martin Proprietary Information, Public Release – LM-MS Export/Import – 26 June 03

Silent Sentry Overview

Silent Sentry’s Passive Coherent Location (PCL) technologies enable

cost-effective, all-weather, persistent passive detection and tracking for

air surveillance and missile targets.

71

Lockheed Martin Proprietary Information, Public Release – LM-MS Export/Import – 26 June 03

NASA Phase 2.3, Fall 2002

KSC

Flagler Co

Airport

Vero

Beach

• Real-time Networked Operation

of 3 Silent Sentry Nodes

• Space Launch Vehicle Tracking

• STS-113

• Delta IV

• Atlas 2A

Historical Event – First EVER Real-Time, 3-D Space Launch

Vehicle Tracking using Indigenous FM Illuminators

73

Tracking of a Cessna 172 light aircraft using FM radio transmission

Courtesy of Craig Tong and Professor Mike Inggs,

University of Cape Town

74

PBR with an aircraft-borne receiver

75

PBR with an aircraft-borne receiver

Willis, N.J. and Griffiths,

H.D. (eds),

Advances in Bistatic Radar

A sequel to Willis, N.J., Bistatic Radar, Artech House,

1991

covering advances in the subject since 1991, and including recently-

declassified information on bistatic radar systems from previous decades,

as well as significant new material on passive bistatic radar.

76

Welcome !

Acknowledgements

Prof. DEN Davies, Dr John Forrest, Dr Jim Schoenenberger (formerly UCL)

Prof. Chris Baker (Ohio State University)

Prof. Ken Milne, Prof. Roger Voles, Prof. Ralph Benjamin, Dr Karl Woodbridge, Dr Alessio Balleri (UCL)

Dr Waddah Al-Ashwal (formerly UCL)

Prof. Mike Inggs, Stephan Sandenbergh (University of Cape Town)

Prof. Simon Watts, Dr Andy Stove (Thales Defence Systems)

Prof. Aaron Lanterman (Georgia Tech)

Tony Andrews (SAIC)

Dr Paul Howland, Darek Maksimiuk (NATO C3 Agency, The Hague)

Marc Lesturgie, Dominique Poullin, Pascale Dubois-Fernandez (ONERA, France)

Dr Chris Pell (formerly UK Ministry of Defence)

Dr Richard White, Michael Dunsmore, Dr Gill Yates (formerly DERA Malvern)

Dr Phil Judkins (Cranfield University)

Col. Michael Svejgaard

78

bistatic and multistatic radar - semantic scholar › 3f61 › fe08e00103aa...willis, n.j.,...

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