dottorato di ricerca in telerilevamento – xxii...

Dottorato di ricerca in Dottorato di ricerca in Telerilevamento Telerilevamento –– XXII cicloXXII cicloRelazione dellRelazione dell’’attivitattivitàà di ricerca di ricerca svolta durante il II annosvolta durante il II anno

Dipartimento INFOCOM – Roma, 21 Ottobre 2008

Carlo Bongioanni

Multichannel Passive Radar: signal processing and experimental prototype development

Tutor: Prof. Pierfrancesco Lombardo

Carlo Bongioanni – Dottorato di ricerca in Telerilevamento (XXII ciclo) Relazione dell’attività di ricerca svolta durante il II anno

2

Outline

� Short summary of first year activity

� PBR processing scheme

� Wide-band prototypes development

� INFOCOM acquisition campaigns

� Experimental results validation: ATC data

� Multi-Frequency detection schemes

� Performance assessment of the Multi-Frequency approach

� A new acquisition device: ICS-554B

� Conclusions and future works

� Publications and conferences


3

Ref SurvDISTURBANCECANCELLATION

2D CROSS-CORRELATION

Surv’

CFAR THRESHOLD

Ref

PBR Processing scheme

REFERENCE CHANNEL

SURVEILLANCE CHANNEL


4

Time varying characteristics of the received FM radio signals

REFERENCE CHANNEL


DISTURBANCECANCELLATION


MULTIPATH REMOVAL

CFAR THRESHOLD

Instantaneous characteristics of the transmitted waveform

� Both range resolution and sidelobe level depend on the instantaneous transmitted waveform on the different FM radio channels (program content)

Instantaneous characteristics of the e.m. environment

� The instantaneous characteristics of the FM channels also depend on the presence/absence of multipath effects (propagation)

� Co- and inter- channel interferences can increase the system noise floor thus reducing the achievable detection performance


5

89.8 MHz 93.8 MHz

92.1 MHz 91.3 MHz 94.3 MHz

Experimental results on the single FM channels

Temporal sequence of three plots on the same Range-Velocity map

0 20 40 60 80 100 120 140 160 180 200

-400

-300

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0

100

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300

400

Relative Bistatic Range [Km]

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6

MULTI-FREQUENCY INTEGRATION

Multi-Frequency detection schemes (I)

Ref

REFERENCE CHANNEL



Doppler Shift

SurvDISTURBANCE CANCELLATION

Surv’

RefCFAR

THRESHOLD

0

1

n

N-1

zn,m n=0,..,N-1, m=0,..,M-1 R.V. z with pz(z) and Dz(z)

xm=f(z0,m, z1,m, …, zN-1,m) m=0,..,M-1 R.V. x with px(x) and Dx(x)


7

Multi-Frequency detection schemes (II)

� The availability of different FM radio channels can collect a huge amount and a large diversity of information

Integration strategies

� Decentralized (“L out of N” logic)

� Centralized Linear:

� SUM

� Centralized Non-Linear:

� MAX

� MIN

1,..,0

1

0

, −==∑−

=

Mmzx

N

n

mnm

{ } 1,..,0max1,..,0, −==

−=Mmzx

Nnmnm

{ } 1,..,0min1,..,0, −==

−=Mmzx

Nnmnm

� Slightly different integration times required

� Noise floor normalization before integration

0

1

n

N-1

zn,m n=0,..,N-1, m=0,..,M-1 R.V. z with pz(z) and Dz(z)

xm=f(z0,m, z1,m, …, zN-1,m) m=0,..,M-1 R.V. x with px(x) and Dx(x)


8

Multi-Frequency detection schemes (III)Theoretical Pfa expressions for the considered integration strategies:

CA-CFAR detection scheme

SUM

MAX

MIN

DECENTRALIZED

CENTRALIZED

nCASUM

nNM

CASUM

N

n

faM

G

MG

M

nnNM

P

+

−+

=−

+

−

−

=

∑ 11

0

M

CAMIN

faMG

MP

+=

−

MN

i CAMAX

iN

n

nfa

iMnG

iM

iN

nN

P

+−

−

= ∑∑

= −

+

=

+

1

1

1

1 )1()1(

∑=

−−

=

N

Li

iNSCfa

iSCfafa PP

iN

P )1(

M

CASC

SCfa

MG

MP

+=

−


9

Theoretical Pfa expressions for the considered integration strategies:

GO-CFAR detection scheme

SUM

MAX

MIN

DECENTRALIZED

CENTRALIZED

∑=

−−

=

N

Li

iNSCfa

iSCfafa PP

iN

P )1( ∑= −

+

+−

=

M

m GOSC

mSCfa

mG

m

mM

P1

1)1(

( )( )

( ) 110110

)(!!!!1

!11

110

1101

0

1

0

1

00−

−

++++−

−

−

−−

=

−

=

−

== +−

++++−−

= ∑∑∑∑

mm

kkkNGOSUM

NGOSUM

m

mN

k

N

k

N

k

mM

m

famG

G

kkkN

kkkN

mM

PLL

LL

∑∑= −

+

=

+

+−

−

=

NM

i GOMAX

iN

n

nfa

inG

i

iNM

nN

P1

1

1

1 )1()1(

∑= −

+

+−

=

M

m GOMIN

mfa

mG

m

mM

P1

1)1(

Multi-Frequency detection schemes (IV)


10

Theoretical Pfa expressions for the considered integration strategies:

SO-CFAR detection scheme

SUM

MAX

MIN

DECENTRALIZED

CENTRALIZED

∑=

−−

=

N

Li

iNSCfa

iSCfafa PP

iN

P )1(MG

MP

SOSC

SCfa

+=

−

MG

MP

SOMINfa

+=

−

lkGl

iNi

MkN

MNPSOMAX

likN

k

iN

l

M

i

fa+

−

−+

−

=

−

+++

=

−+

=

−

=

∑ ∑∑1

)1(1)1(1 1

1

1)1(

0

1

0

( ) 110110

1

1

0 110

1101

0

1

0 )(!!!!1

)!1(1

−−

++++−−

−−

= −

−−

=

−

= +−

++++−−= ∑∑∑

MM

kkkNGOSUM

NSOSUM

N

k M

MN

k

N

k

faMG

G

kkkN

kkkNP

LL

LL

Multi-Frequency detection schemes (V)


11

Wide-Band Prototypes development

RFIF

RF IF

LO

Dual channel

A/D Converter

RF Amp.Down Conv

MIXER

RF Amp.

IF Amp.

IF Amp.Down Conv

MIXER

Low-pass

Filter

Low-pass

Filter

SurveillanceAntenna

Dual channel

A/D Converter

External

Clock Source

1st Nyquist

FM Band

(88 ÷ 108 MHz) Fs 0 Fs/2

2nd Nyquist

ReferenceAntenna

Direct RF sampling

Signal down-conversion & baseband sampling


12

� RX site: Riva di Traiano (Civitavecchia, ~70km north of Rome)

� Reference antenna steered toward Monte Argentario (pointing north-west)

� Surveillance antenna pointed at about 180° (standard arrival and departure routes to and from Leonardo Da Vinci airport in Fiumicino)

� Selection of a limited number of FM radio channels

� 300 data files covering 2 hours

� Single acquisition duration: about 1 sec

� Temporal spacing between acquisitions: about 23 sec

� Live ATC registrations available

INFOCOM Acquisition campaigns


13

Example: 17 May 2007 acquisition

Single channel (93.8MHz) Multi-Frequency integration: 89.8, 92.1, 93.8MHz (nominal Pfa = 10-4)

Experimental results validation: ATC data

� Comparison between detection results and live air traffic control registrations

� Performance evaluation for the implemented system: Pd e Pfa


14

Performance assessment of the MF approach (I)

Extensive performance evaluation for the Multi-Frequency approaches

� 5 different MF configurations considered:

� MFC2: 89.8 + 93.8 MHz

� MFC3: 89.8 + 93.8 + 92.1 MHz

� MFC4a: 89.8 + 93.8 + 92.1 + 91.3 MHz

� MFC4b: 89.8 + 93.8 + 92.1 + 94.3 MHz

� MFC5: 89.8 + 93.8 + 92.1 + 91.3 + 94.3 MHz

ΔR1: 5 ÷ 35 km ΔR2: 35 ÷ 65 km ΔR3: 65 ÷ 95 km

� CA-CFAR and GO-CFAR: obtained False Alarm Rates are largely comparable with the nominal Pfa value (10-3)

� SO-CFAR: limited robustness when applied against real data


15

Performance assessment of the MF approach (II)

SFC1 SFC2 SFC3 SFC4 SFC5 MFC2 MFC3 MFC4a MFC4b MFC5 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Single/Multi-Frequency Configurations

Dete

ction R

ate

∆R1

∆R2

∆R3


0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1


Dete

ction R

ate

∆R1

∆R2

∆R3


0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1


Dete

ction R

ate

∆R1

∆R2

∆R3

Comparison between single frequency channels (SFC1-5) and the decentralized integration strategies (Pfa = 10-3)

CA-CFAR GO-CFAR

SO-CFAR


16

Performance assessment of the MF approach (III)

False alarm rates obtained with the different centralized integration strategies in conjunction with the different CFAR detection schemes (nominal Pfa = 10-3)

� CA-CFAR and GO-CFAR: proper control of the Pfa with all the considered integration schemes

� SO-CFAR: false alarm rate comparable with the nominal one only in few cases

� MAX approach (both with CA and GO-CFAR) yields slightly higher false alarm rates at short ranges: disturbance residuals in Range-Velocity map


17

Performance assessment of the MF approach (IV)

Comparison among the different centralized integration strategies (Pfa = 10-3)

CA

-CF

AR

GO

-CF

AR

MFC2 MFC3 MFC4aMFC4b MFC5 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Multi-Frequency Configurations

Dete

ction R

ate

LINEAR


0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1


Dete

ction R

ate

MAX


0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1


Dete

ction R

ate

MIN

∆R1

∆R2

∆R3


0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1


Dete

ction R

ate

LINEAR


0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1


Dete

ction R

ate

MAX


0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1


Dete

ction R

ate

MIN

∆R1

∆R2

∆R3

� MIN approach always yields worst performance

� SUM (LINEAR) and MAX integration strategies show similar performance

� SUM has slight advantage at far range

� MAX is slightly better than SUM in detection probability when using a small number of integrated channels

� CA-CFAR seems preferable with respect to GO-CFAR (slight performance improvement)


18

Performance assessment of the MF approach (V)

Detection performance comparison of the best performing integration strategies using a CA-CFAR detection scheme (Pfa = 10-3)


0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1


Dete

ction R

ate

∆R1


0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1


Dete

ction R

ate

∆R2


0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1


Dete

ction R

ate

∆R3

SUM

MAX

DEC

SC2

SC1

SUM

MAX

DEC

SC2

SC1

SUM

MAX

DEC

SC2

SC3

� Detection capability limited due to the long baseline between the TX and RX site

� Proposed multi-frequency approaches yield a remarkable performance improvement with respect to the best single-channels case for all the considered surveillance regions


19

ICS-554B: main features

� Simultaneous down-conversion of up to 16 arbitrary signal bands (e.g. 16 FM channels): onboard decimation, software selectable

Technical Specifications:� 4 analog input channels (4 ADCs)

� ADC resolution: 14 bits

� Input impedance: 50Ohm

� Full scale input: 1.2 Vpk-pk (about 5.5dBm)

� Input Signal Bandwidth: 2MHz ÷ 200MHz

� Internal or external clock and trigger

� Max. Sampling Rate: 100MHz for 4 channels, simultaneous

� Min. Sampling Rate: 30MHz for 4 channels, simultaneous

� Internal Sample Clock Oscillator: 100MHz fixed frequency crystal

� Spurious Free Dynamic Range (SFDR): > 85dB

� Signal-to-Noise Ratio (SNR): > 71dB

� User Programmable FPGA (1 million gates)

� SMA coaxial connectors

� ADC outputs are applied to a bank of 4 digital down-converter (DDC) modules (Graychip GC4016 devices)

� Each GC4016 device includes 4 independent DDC channels


20

ICS-554B: block diagram

� Several operation modes available

� Examples of acquisition configurations:

� 2 antennas (2 ADC channels), 16 FM channels (8+8)

� 4 antennas (4 ADC channels), 16 FM channels (4+4+4+4)

� …


21

ICS-554B: GC4016 block diagrams

� Each GC4016 device can be configured for 4, 2 or 1 output channel

� Each DDCs can have independent frequency, phase and gain controls


22

Conclusions and future works (I)

� The development of wideband experimental prototypes allowed us to apply a multi-frequency approach which enhances the surveillance capabilities of PBR.

� The proposed approach yields improved performance w.r.t. the single FM radio channels, since it makes the detection robust w.r.t. both the content of transmitted radio broadcast channel and the channel multipath conditions.

� The performance improvement is paid in terms of computational load

� In the specific considered case, a significant increase in the number of integrated channels does not yield a further performance improvement (poorer characteristics of additional channels).

� Further improvement expected by adding good-performing channels (when available).

� Detection performance is still limited by interferences due to other FM radio transmissions…


23

Conclusions and future works (II)

Different strategies can be considered to improve the detection performance:

� Automatic selection of the FM radio channels

� Direct signal-to-Noise Ratio (DNR): this parameter allows to identify high power transmissions and strongly affects theoretical cancellation and detection performance

� Reference to Surveillance Power Ratio (Front-to-Back ratio)

� Program content

� Interference rejection based on the exploitation of different polarizations

� different FM radio channels transmitted with different polarizations, even from the same transmitter: use of more than two receiving channels


24

Conclusions and future works (III)

Different strategies can be considered to improve the detection performance:

� Antenna based interference rejection using multiple receiving channels

� Direction of Arrival (DOA) estimation

� example: one reference channel and two surveillance channels toperform detection and DOA estimation based on phase differences evaluation (monopulse)

� DOA estimation with a multi-channel and multi-frequency configuration

� Track initiation

� Multi-temporal analysis (used together with multi-frequency approach)


25

Conclusions and future works (IV)

Exploitation of different opportunity waveforms: digital TV signals

� Frequency range:

� 52 ÷ 88 and 174 ÷ 230 MHz VHF

� 470 ÷ 870 MHz UHF

� Wider bandwidth: 7 ÷ 8 MHz increased range resolution

� High power transmissions

� Wide coverage:

� switch-off of analogical transmissions already started

� Lazio: II semester of 2009

� OFDM modulation

� Presence of deterministic peaks


26

Publications and conferences

� A. Lauri, F. Colone, R. Cardinali, C. Bongioanni, P. Lombardo, “Analysis and emulation of FM radio signals for passive radar”, 2007 IEEE Aerospace Conference, Big Sky (MT), USA, 3-10 March 2007

� C. Bongioanni, F. Colone, S. Bernardini, L. Lelli, A. Stavolo, P. Lombardo, “Passive radar prototypes for multifrequency target detection”, Signal Processing Symposium 2007, Jachranka Village (Poland), 24-26 May 2007

� F. Colone, P. Lombardo, C. Bongioanni, “Track initiation for FM-based passive radar using multi-frequency and multi-temporal integration”, 5th Multi-National Passive Covert Radar Conference, Shrivenham, Swindon (UK), 13-15 November 2007

� P. Lombardo, F. Colone, C. Bongioanni, “Comparison of different approaches for a Multi-Frequency FM Based Passive Bistatic Radar”, Sensors and Technology for Defence Against Terrorism, Mannheim, Germany, 22-25 April 2008

� P. Lombardo, F. Colone, C. Bongioanni, A. Lauri, T. Bucciarelli, “PBR activity at INFOCOM: adaptive processing techniques and experimental results”, 2008 IEEE Radar Conference, Rome (Italy), 26-30 May 2008

� C. Bongioanni, F. Colone, P. Lombardo, “Performance Analysis of a Multi-Frequency FM Based Passive Bistatic Radar ”, 2008 IEEE Radar Conference, Rome (Italy), 26-30 May 2008 (Best student paper award)

� F. Colone, C. Bongioanni, P. Lombardo, “Multi-Frequency target detection in FM Radio Based Passive Bistatic Radar”, IEEE Transactions on Aerospace and Electronic Systems (attualmentein revisione)

dottorato di ricerca in telerilevamento – xxii...

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