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UNCLASSIFIED
ADT
Alternative Detection Techniques
to Supplement PSR Coverage
Contract N° C06/11267CG
Final Report
Prepared for:
EUROCONTROL
Prepared by:
THALES AIR SYSTEMS
F8224
Date :
DOCUMENT NUMBER
FORMAT/SIZE
PAGE
TR6/SR/PST-041/07
A4
1/77
28th February 2007
Ce document et les informations qu’il contient sont la propriété d’EUROCONTROL.
Ce document ne peut être, en totalité ou en partie, ni reproduit ni communiqué, par
aucun moyen ni sous aucune forme sans l’autorisation préalable écrite
d’EUROCONTROL.
A 100 08/97 1/3 W6
Rev. -
This document and the information contained within it are the property of the
EUROCONTROL Agency. No part of this report may be reproduced and/or
disclosed, in any form or by any means without the prior written permission of the
owner
UNCLASSIFIED
APPROVALS
Rev/Date
-/ 28th Feb. 2007
A/
NA
M. MORUZZIS
<name>
<name>
<name>
Date :
Date :
Date :
Date :
NA
NA
NA
Approved by
D. MULLER
<name>
<name>
<name>
Date :
Date :
Date :
Date :
NA
NA
NA
R. YOUSSEFI
<name>
<name>
<name>
Date :
Date :
Date :
Date :
TR6/SR/PST-041/07
Ce document et les informations qu’il contient sont la propriété d’EUROCONTROL. Ce document
ne peut être, en totalité ou en partie, ni reproduit ni communiqué, par aucun moyen ni sous aucune
forme sans l’autorisation préalable écrite d’EUROCONTROL.
A 100 11/97 2/3 W6
C/
NA
NA
Written by
Quality
Assurance
B/
28 Feb. 2007
Rev -
2/77
This document and the information contained within it are the property of the EUROCONTROL
Agency. No part of this report may be reproduced and/or disclosed, in any form or by any means
without the prior written permission of the owner
UNCLASSIFIED
CHANGES
REVISION
INDEX
-
DESCRIPTION OF CHANGE
Initial version
th
28 Feb.2007
A
NA
<date>
B
NA
<date>
C
NA
<date>
TR6/SR/PST-041/07
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UNCLASSIFIED
LIST OF CONTENTS
1.
EXECUTIVE SUMMARY............................................................................................................ 10
2.
SCOPE ....................................................................................................................................... 11
2.1
2.2
2.3
IDENTIFICATION ....................................................................................................................... 11
PURPOSE OF THE STUDY....................................................................................................... 11
PURPOSE OF THE DOCUMENT .............................................................................................. 11
3.
DOCUMENTS............................................................................................................................. 12
3.1
APPLICABLE DOCUMENTS...................................................................................................... 12
3.1.1
Documents from the Customer............................................................................................ 12
3.1.2
Other Applicable Documents............................................................................................... 12
3.2
REFERENCE DOCUMENTS ..................................................................................................... 13
3.3
BIBLIOGRAPHY ......................................................................................................................... 13
4.
INTRODUCTION ........................................................................................................................ 15
5.
RESULTS ................................................................................................................................... 15
5.1
CONCEPT DEFINITION............................................................................................................. 15
5.2
CONCEPT ANALYSIS................................................................................................................ 23
5.2.1
Review of Possible system architectures ............................................................................ 23
5.2.2
Frequency Allocation Issues................................................................................................ 27
5.2.3
Parametric Performance prediction ..................................................................................... 33
5.3
PRELIMINARY DEFINITIONS.................................................................................................... 39
5.3.1
Approach Configuration Preliminary Definition .................................................................... 39
5.3.2
En-Route Configuration Preliminary Definition .................................................................... 55
5.3.3
Interfaces and Constraints................................................................................................... 60
5.3.4
Main Operational Benefits and Future Growth Potential ..................................................... 65
5.4
FEASIBILITY AND RELATIVE COST ANALYSIS ...................................................................... 66
5.4.1
Feasibility Analysis .............................................................................................................. 66
5.4.2
Relative Cost Analysis......................................................................................................... 72
5.5
RECOMMENDATIONS .............................................................................................................. 76
5.5.1
Recommendations for future Applications........................................................................... 76
5.5.2
Recommendations for future Studies .................................................................................. 76
6.
CONCLUSIONS ......................................................................................................................... 77
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UNCLASSIFIED
LIST OF FIGURES
FIGURE 1: PROPOSED AREAS FOR THE MSPSR SYSTEM PRELIMINARY DEFINITION ......................................16
FIGURE 2: DISTRIBUTION OF MAXIMUM ALTITUDES (LINERS) .......................................................................17
FIGURE 3: DISTRIBUTION OF MAXIMUM VELOCITIES (LINERS)......................................................................17
FIGURE 4: DISTRIBUTION OF MINIMUM (LANDING) VELOCITIES (LINERS) .......................................................18
FIGURE 5: MSPSR GENERAL CONCEPT ....................................................................................................19
FIGURE 6: PRINCIPLE OF THE MSPSR MULTISTATIC DETECTION.................................................................19
FIGURE 7: PRINCIPLE OF THE MSPSR SYNCHRONISATION .........................................................................20
FIGURE 8: PRINCIPLE OF ELLIPSOID INTERSECT ..........................................................................................21
FIGURE 9: PRINCIPLE OF GDOP................................................................................................................22
FIGURE 10: AMBIGUITY FUNCTIONS (FMCW -LEFT-, NOISE -MIDDLE-, MULTI-TONE -RIGHT-) ........................26
FIGURE 11: ATMOSPHERIC ATTENUATION (ACCORDING TO REF. [4.1]).........................................................27
FIGURE 12: RAIN (LEFT) AND GROUND (RIGHT) CLUTTER REFLECTIVITY (ACCORDING TO REF. [1.2]).............28
FIGURE 13: LOW ALTITUDE DETECTION COMPARED CAPABILITIES UHF (LEFT) & X-BAND (RIGHT) .................28
FIGURE 14: ITU TAXONOMY OF “RADIODETERMINATION” SERVICES ............................................................29
FIGURE 15: FREQUENCIES ALLOCATED TO AERONAUTICAL RADIONAVIGATION SERVICES (UHF/S/L BANDS).30
FIGURE 16: FREQUENCIES ALLOCATED TO RADIOLOCATIONS SERVICES (UHF/S/L BANDS) ..........................31
FIGURE 17: A POSSIBLE MSPSR TRANSMISSION FREQUENCY SCHEME .......................................................32
FIGURE 18: SIMPLE BISTATIC SITUATION (LEFT) AND ASSESSMENT GRID (RIGHT) .........................................34
FIGURE 19: EXAMPLE OF BISTATIC COVERAGE (HORIZONTAL PLANE, UAV AT 1000M AGL)..........................34
FIGURE 20: EXAMPLE OF BISTATIC COVERAGE (VERTICAL PLANE) ...............................................................35
FIGURE 21: COVERAGE WITH VARIOUS CLUTTER: NO CLUTTER(TR), GROUND(TL), RAIN(BL), GROUND+RAIN(BR)36
FIGURE 22: DOPPLER VELOCITIES: TARGET (TOP), RAIN MAXIMUM VALUE(BL), RAIN MINIMUM VALUE (BR) ......37
FIGURE 23: INTERFERENCE RESIDUES: DIRECT PATH(TL), GROUND CLUTTER(BL), RAIN CLUTTER(BR)............38
FIGURE 24: MSPSR CELL ........................................................................................................................39
FIGURE 25: ASSESSMENT GRIDS: Z=100M (TOP LEFT), Z=1000M (TOP RIGHT), VERTICAL (BOTTOM)............43
FIGURE 26: UAV, HORIZONTAL COVERAGE, 100M , MEAN POD (LEFT) & SYSTEM POD (RIGHT) ..................44
FIGURE 27: UAV, HORIZONTAL COVERAGE, 100M, XY ACCURACY (LEFT) & Z ACCURACY (RIGHT) ..............44
FIGURE 28: UAV, HORIZONTAL COVERAGE, 1000M, MEAN POD (LEFT) & SYSTEM POD (RIGHT) .................45
FIGURE 29: UAV, HORIZONTAL COVERAGE, 1000M, XY ACCURACY (LEFT) & Z ACCURACY (RIGHT) ............45
FIGURE 30: UAV, VERTICAL COVERAGE, MEAN POD (LEFT) & SYSTEM POD (RIGHT)..................................46
FIGURE 31: UAV, VERTICAL COVERAGE, XY ACCURACY (LEFT) & Z ACCURACY (RIGHT) .............................46
FIGURE 32: BIZJET, HORIZONTAL COVERAGE, 100M , MEAN POD (LEFT) & SYSTEM POD (RIGHT) ...............47
FIGURE 33: BIZJET, HORIZONTAL COVERAGE, 100M, XY ACCURACY (LEFT) & Z ACCURACY (RIGHT)............47
FIGURE 34: BIZJET, HORIZONTAL COVERAGE, 1000M, MEAN POD (LEFT) & SYSTEM POD (RIGHT) ..............48
FIGURE 35: BIZJET, HORIZONTAL COVERAGE, 1000M, XY ACCURACY (LEFT) & Z ACCURACY (RIGHT)..........48
FIGURE 36: BIZJET, VERTICAL COVERAGE, MEAN POD (LEFT) & SYSTEM POD (RIGHT) ...............................49
FIGURE 37: BIZJET, VERTICAL COVERAGE, XY ACCURACY (LEFT) & Z ACCURACY (RIGHT) ..........................49
FIGURE 38: LINER, HORIZONTAL COVERAGE, 100M , MEAN POD (LEFT) & SYSTEM POD (RIGHT).................50
FIGURE 39: LINER, HORIZONTAL COVERAGE, 100M, XY ACCURACY (LEFT) & Z ACCURACY (RIGHT) .............50
FIGURE 40: LINER, HORIZONTAL COVERAGE, 1000M, MEAN POD (LEFT) & SYSTEM POD (RIGHT) ...............51
FIGURE 41: LINER, HORIZONTAL COVERAGE, 1000M, XY ACCURACY (LEFT) & Z ACCURACY (RIGHT) ...........51
FIGURE 42: LINER, VERTICAL COVERAGE, MEAN POD (LEFT) & SYSTEM POD (RIGHT) ................................52
FIGURE 43: LINER, VERTICAL COVERAGE, XY ACCURACY (LEFT) & Z ACCURACY (RIGHT)............................52
FIGURE 44: EN-ROUTE COVERAGE GRID ....................................................................................................55
FIGURE 45: LINER, EN-ROUTE VERTICAL COVERAGE, MEAN POD (LEFT) & SYSTEM POD (RIGHT)................56
FIGURE 46: LINER, EN-ROUTE VERTICAL COVERAGE, XY ACCURACY (LEFT) & Z ACCURACY (RIGHT) ...........56
FIGURE 47: EN-ROUTE TIME HISTORY ........................................................................................................57
FIGURE 48: LINER, EN-ROUTE TIME HISTORY, MEAN POD (LEFT) & SYSTEM POD (RIGHT) ...........................57
FIGURE 49: LINER, EN-ROUTE TIME HISTORY, XY ACCURACY (LEFT) & Z ACCURACY (RIGHT).......................57
FIGURE 50: VISIBILITY OF A LA SITED MONOSTATIC RADAR (LEFT: 100M AGL, RIGHT: 4000M ASL).............61
FIGURE 51: VISIBILITY OF A HA SITED MONOSTATIC RADAR (LEFT: 100M AGL, RIGHT: 4000M ASL) ............62
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FIGURE 52: VISIBILITY OF A MULTISTATIC RADAR (LEFT: 100M AGL, RIGHT: 4000M ASL)............................63
FIGURE 53: A SCHEMATIC EXAMPLE OF DEPLOYMENT IN A MOUNTAINOUS REGION ........................................63
FIGURE 54: SCHEME OF A TRANSMITTER ...................................................................................................66
FIGURE 55: SCHEME OF A RECEIVER .........................................................................................................67
FIGURE 56: A POSSIBLE RX ANTENNA DESIGN ............................................................................................68
FIGURE 57: A POSSIBLE RX ANTENNA DIAGRAMS ........................................................................................68
FIGURE 58: CONVENTIONAL RADAR DIAGRAM ............................................................................................69
FIGURE 59: CONVENTIONAL MULTIFREQUENCY RADAR DIAGRAM ................................................................69
FIGURE 60: MULTIFREQUENCY W IDEBAND ADC RADAR DIAGRAM ..............................................................70
FIGURE 61: DIGITAL RADAR ......................................................................................................................70
FIGURE 62: GENERIC MSPSR RX COHERENT PROCESSING .......................................................................71
FIGURE 63: DEVELOPMENT PLANNING (GIVEN FOR ILLUSTRATION PURPOSE) ...............................................73
FIGURE 64: “ZERO-SPARE” MAINTENANCE CONCEPT..................................................................................74
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UNCLASSIFIED
LIST OF TABLES
TABLE 1: APPLICABLE DOCUMENTS (EXTERNAL TO TR6) ............................................................................12
TABLE 2: APPLICABLE DOCUMENTS (INTERNAL TO TR6) .............................................................................12
TABLE 3: REFERENCE DOCUMENTS ...........................................................................................................13
TABLE 4: BIBLIOGRAPHY ...........................................................................................................................14
TABLE 5: PROPOSED COMPLEMENTARY DEFINITIONS .................................................................................16
TABLE 6: PROPOSED AREAS FOR THE MSPSR SYSTEM PRELIMINARY DEFINITION ........................................16
TABLE 7: RX/TX ARCHITECTURE COMPARISON TABLE .................................................................................23
TABLE 8: W AVEFORM COMPARISON TABLE .................................................................................................26
TABLE 9: ITU TERMS AND DEFINITIONS (EXTRACTS)...................................................................................29
TABLE 10: RADIONAVIGATION SYSTEMS (FREQUENCY BANDS) ...................................................................30
TABLE 11: TX CHARACTERISTICS ...............................................................................................................40
TABLE 12: RX CHARACTERISTICS...............................................................................................................41
TABLE 13: TYPICAL TARGETS ....................................................................................................................41
TABLE 14: TABLE OF SCENARIOS ...............................................................................................................42
TABLE 15: SUMMARY OF DETECTION PERFORMANCE ..................................................................................53
TABLE 16: INTERFACES WITH THE EXISTING INFRASTRUCTURE ....................................................................60
TABLE 17: LOGICAL DATA EXCHANGES BETWEEN CENTRAL UNIT AND ATC CENTRE ....................................60
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UNCLASSIFIED
LIST OF ACRONYMS
ADBF
ADC
ADT
AGL
APD
APD
ASL
ATC
ATM
BIT
bl
br
CFAR
COM
CW
DBF
DC
DME
EM
FFT
FM
FMCW
FPGA
FWA
GDOP
GFE
GPS
ILS
ITU
LNA
LO
LOS
MLS
MMN
MSPSR
NA
NDB
OFDM
Pfa
PoD
PSK
PSR
RCS
RF
RPM
RSG
Rx
Adaptive Digital Beam-Forming
Analog to Digital Converter
Alternative DetectionTechniques
Above Ground Level
Amplitude Phase Detector
Amplitude Probability Distribution
Above Sea Level
Air Traffic Control
Air Traffic Management
Built-In Test
bottom left
bottom right
Constant False Alarm Rate
COMmunication
Continuous Wave
Digital Beam Forming
Direct Current
Distance Measuring Equipment
Electro Magnetic
Fast Fourier Transform
Frequency Modulation
Frequency Modulation Continuous Wave
Field-Pgrogrammable Gate Array
Fixed Wing Aircraft
Geometrical Dilution Of Precision
Government Furnished Equipment
Global Positioning System
Instrument Landing System
International Telecommunication Union
Low Noise Amplifier
Local Oscillator
Line Of Site
Microwave Landing System
Man Made Noise
Multi-Static Primary Surveillance Radar
Not Applicable
Non Directional Beacon
Orthogonal Frequency Division Multiplexing
Probability of False Alarm
Probability of Detection
Phase Shift Keying
Primary Surveillance Radar
Radar Cross Section
Radio Frequency
Rotation Per Minute
Radar Signal Generation
Receiver
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UNCLASSIFIED
LIST OF ACRONYMS (ct’d)
SIR
SLL
TAD
TBC
tl
TMA
tr
TR6
TRL
Tx
UAV
UHF
UWB
VOR
WAAS
WP
WRC
Signal to Interference Ratio
Side Lobe Level
THALES Air Defence
To Be Completed
top left
Terminal Manoeuvring Area
top right
THALES Air Systems
Technical Readiness Level
Transmitter
Unmanned Aerial Vehicle
Ultra High Frequency (300 MHz to 1000 MHz)
Ultra Wide Band
VHF Omnidirectional Range
Wide Area Augmentation System
Work Package
World Radiocommunication Conference
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UNCLASSIFIED
1. EXECUTIVE SUMMARY
This Final Report is prepared by THALES Air Systems for EUROCONTROL in execution of the
Contract N° C06/11267CG relative to the ADT (“Alternative Detection Techniques to Supplement PSR
Coverage) study.
The activities conducted in the frame of this study are very encouraging and give a strong feeling on
the feasibility of a Multi-Static PSR system to Supplement PSR Coverage.
It is based on a sparse network of omnidirectional UHF transmitters (Tx) and omnidirectional receivers
(Rx) interconnected to a Central Unit. It establishes a 3D non-dependant air situation including noncooperative targets (such as UAVs and ULAs). The configuration is adaptable to the environment and
reconfigurable. It could re-use existing infrastructures such as communication masts.
Assessments show that its performance comply with the requirements for Approach/TMA even on low
RCS targets (e.g. UAVs).
The coverage can be extended by adding Tx and Rx as necessary, in order to correspond to various
applications such as Approach or En-route, and also in difficult regions such as mountains.
It offers several improvements compared to a conventional PSR:
• 3D detection in position and velocity,
• higher renewal rate (e.g. 1.5 s instead of 4-5 s),
• resistance to Man-Made Noise and Wind-farms effects.
The MSPSR acquisition cost is estimated between 55% and 65% of a classical (2D) PSR. In addition,
its fail-soft design is compatible with a “Zero-spare” maintenance concept, which also reduces the total
Life Cycle Cost.
The envisaged system also offers many growth potentials in certainly valuable domains such as:
• target recognition (e.g. using Doppler), including:
o classification of the type of target (jet, helicopter, propeller driven…)
o Wake-Vortex detection and monitoring,
o Wind-Farm effects filtering,
• detection and tracking of surface mobile targets,
• integrated wind profiling,
In addition, the MSPSR concept has many advantages for military applications, such as:
• a design naturally compatible with tactical constraints,
• a capacity to detect/ locate weapons and provide alarms,
• a high level of resilience (transmitters and receivers being spread, the system sustaining the
loss of one or two elements, ECCM features being already included in the original design…),
• an attractive performance/cost trade-off (reinforced by its high communalities with civilian
domain).
The main issue is certainly the frequency allocation mainly in the domain of the so called “Spectrum
Dividend” in the sense that the envisaged system would find a natural application in the low UHF band.
Some initial actions have already been undertaken and must be pursued in the perspective of WRC
2007, 2010 and 2013.
It is recommended to conduct a follow-on study dedicated to the solving of main issues (e.g. EM
compatibility, propagation at low altitude, safety analysis…), including detailed simulation and live tests
using a demonstrator.
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UNCLASSIFIED
2. SCOPE
2.1 IDENTIFICATION
This document is the Final Report (Deliverable WP1.6) of the ADT (“Alternative Detection Techniques
to Supplement PSR Coverage) study, conducted by THALES Air Systems for EUROCONTROL, in
execution of the Contract N° C06/11267CG.
2.2 PURPOSE OF THE STUDY
The EUROCONTROL Surveillance Domain is tasked with investigating whether new technologies or
alternative uses of recent advances in existing technologies could be used to support the provision of
surveillance data.
One of these candidate technologies is a Multi-Static PSR technique (“MSPSR”), previously employed
in a defence type arena. These make use of dedicated transmissions made in a coherent way by
multiple low power ground-based transmitters. The perturbations caused by an aircraft disturbing the
transmissions would be processed by ground-based receiver stations and a declaration of an aircrafts
presence could be made.
This study is to assess the feasibility and current status of this surveillance technique to fulfil civilian
ATM applications.
2.3 PURPOSE OF THE DOCUMENT
This document gathers the results which have been obtained during the study.
It is organised as follows:
• Chapter 3 reminds the list of applicable documents and other documents useful for the study,
• Chapter 4 introduces the subject,
• Chapter 5 describes the results obtained for each work-package:
o 5.1 Concept Definition,
o 5.2 Concept Analysis,
o 5.3 Preliminary Definitions,
o 5.4 Feasibility and Relative Cost Analysis,
o 5.5 Recommendations.
• Chapter 6 is devoted to conclusions.
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UNCLASSIFIED
3. DOCUMENTS
3.1 APPLICABLE DOCUMENTS
3.1.1 DOCUMENTS FROM THE CUSTOMER
Num.
[1.1]
[1.2]
Title
Reference
Terms and Conditions applicable to Contract
C06/11267CG
N° C06/11267CG
Requirements Specification for a Study into
Alternative Detection Techniques to
06/03/20-3
Supplement PSR Coverage
Version
Final
2.0
Date
22/08/06
th
1,1
4 April
2006
Reference
Version
Date
TAD/SR/RSSB/045/06
-
05 June
2006
Table 1: Applicable documents (external to TR6)
3.1.2 OTHER APPLICABLE DOCUMENTS
Num.
[2.1]
[2.2]
[2.3]
[2.4]
[2.5]
Title
Alternative Detection Techniques to
Supplement PSR Coverage
Reply to the tender A06/11043CG
ADT Meeting to present initial progress
Minutes of Meeting
ADT First Draft Report
ADT Presentation/ Review of first draft report
Minutes of Meeting
ADT Executive Summary on Frequency
Allocation Issues
th
th
TAD/SR/RSSB/076/06
TAD/SR/RSSB/083/06
TAD/SR/RSSB/086/06
TAD/SR/RSSB/089/06
-
[2.6]
ADT Draft Final Report
TAD/SR/PST-019/06
-
[2.7]
TAD/SR/PST-019/06
A
[2.8]
TAD/SR/PST-019/06
B
[2.9]
ADT Presentation/ Review of draft final
report
Minutes of Meeting
TR6/SR/PST-039/07
-
04 Oct.
2006
th
15 Nov.
2006
st
01 Dec.
2006
st
01 Dec.
2006
th
28 Dec.
2006
th
07 Feb.
2007
th
09 Feb.
2007
th
13 Feb.
2007
Table 2: Applicable documents (internal to TR6)
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UNCLASSIFIED
3.2 REFERENCE DOCUMENTS
Num.
[3.1]
Title
Reference
-
TAD Quality Manual
Version
Date
March 2006
Table 3: Reference documents
3.3 BIBLIOGRAPHY
Num.
[4.1]
[4.2]
[4.3]
[4.4]
[4.5]
[4.6]
[4.7]
[4.8]
[4.9]
[4.10]
[4.11]
[4.12]
Title
Radar Handbook
M. Skolnik
Introduction to Radar Systems
M.I. Skolnik
Radar Design Principles
Signal Processing and the environment
F.E. Nathanson
High Resolution Radar
D.R. Wehner
Bistatic Radar
N. J. Willis
The European Table of Frequency Allocation
and Utilisation Covering the Frequency
Range 9 kHz to 275 GHz
EU Spectrum Policy priorities for the digital
switchover in the context of the upcoming
ITU Regional Radiocommunication
Conference 2006 (RRC-06)
The Surveillance Strategy for ECAC
J. Berends, A. Desmond-Kennedy
EUROCONTROL Standard Document for
Radar Surveillance in En-Route and Major
Terminal Areas
Towards a Range-Doppler UHF Multistatic
Radar for the Detection of Non-Cooperative
Targets with Low RCS
E.G. Alivizatos, M.N. Petsios, N.K. Uzunoglu
J. of Electromagn. Waves and Appl.
Multiband Multistatic Synthetic Aperture
Radar for Measuring Ice Sheet Basal
Conditions
J. Paden, S. Mozaffar, D. Dunson, C. Allen,
S. Gogipeni, T. Akins
IGARSS’04, September 21-24, Anchorage
Object Tracking in a 2D UWB Sensor
Network
Cheng C., A. Sahai
Asilomar Conference on Signals,. Systems
and Computers, Pacifec Grove, CA,
November 2004
TR6/SR/PST-041/07
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Reference
Version
Date
nd
1990
rd
2001
nd
1999
Mc Graw Hill, Inc
2 Ed.
Mc Graw Hill, Inc
3 Ed.
SciTech
2 Ed.
Artech House
2
nd
Ed.
1995
Artech House
-
1991
ERC Report 25
-
2004
COM(2005) 461 final
-
29.9.2005
EUROCONTROL
5/10/17-2
2.0
18 Nov.
2005
SUR.ET1.ST01.1000STD-01601
1.0
March 1997
Vol. 19, N0 15, 20152031, 2005
-
2005
-
-
2004
-
-
2004
28 Feb. 2007
Rev -
13/77
UNCLASSIFIED
Num.
[4.13]
[4.14]
[4.15]
[4.16]
[4.17]
[4.18]
[4.19]
[4.20]
[4.21]
[4.22]
Title
Bistatic and Multistatic Radar Sensors for
Homeland Security
C.J. Baker, H.D Griffiths
NATO ASI on Advanced in Sensing with
Security Applications
The last decades and the future of low
frequency radar concepts in France
M. Lesturgie, J.P. Eglizeaud, G. Auffray, D.
Muller, B. Olivier, C. Delhote
Interests and capabilities of low frequencies
for surface radars
B. Olivier, J.L. Zolesio
On the verification of beyond the horizon
detection capabilities of V/UHF radars
M. Kerambelec, M. Hurtaud, Kushel,
Cavallari
Low frequency radar design trade offs
M. Lesturgie, J.L. Zolesio
Reference
Version
Date
-
-
2005
SEE International
Radar 2004
Conference, Toulouse
-
2004
Colloque international
sur le radar , Brest
1999
-
1999
Colloque international
sur le radar , Brest
1999
-
1999
-
2001
-
11-15
December
2006
-
December
2001
Issue 2
September
2003
-
2003
-
September
2003
Workshop ODAS
2001, Paris
ICAO Aeronautical
Development of New Primary Radar
Communications
Technology
Panel (ACP)
(Presented by the EUROCONTROL Agency) Sixteenth Meeting of
the Working Group F
Montreal, Canada
Man-Made Noise Power Measurements at
VHF And UHF Frequencies
NTIA Report 02-390
Robert J. Achatz and Roger A. Dalke
Man-Made Noise Measurement Programme
Mass Consultants
(AY4119)
Limited
Final Report
Feasibility of Mitigating the effects of
ETSU
Windfarms on Primary Radar
W/14/00623/REP
M.M. Butler, D.A. Johnson
DTI PUB URN No.
Alenia Marconi Systems Limited
03/976
Wind Farms Impact on Radar Aviation
FES
Interests
W/14/00614/00/REP
Gavin J Poupart
DTI PUB URN No.
QinetiQ
03/1294
th
[4.23]
[4.24]
[4.25]
Recommendation of the IEEE (relative to EM IEEE Std C95.1, 1999
Radiation hazards)
Edition
Recommendation of the European Council
1999/519/CE
(relative to EM Radiation hazards)
Directive of the European Council (relative to
2004/40/CE
EM Radiation hazards)
-
8
December
1998
th
12 July
1999
th
29 April
2004
Table 4: Bibliography
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4. INTRODUCTION
This Final Report describes the works achieved in the objective of assessing the feasibility of a MultiStatic PSR (MSPSR) system, able to supplement PSR coverage for future ATM applications.
th
The study started on 28 August, 2006 and three meetings were held:
th
• on 04 October 2006 for presenting the initial progress (see Ref. [2.2]),
th
• on 28 November 2006 for presenting/reviewing the First Draft Report (see Ref. [2.3] and
[2.4]).
th
• on 12 February 2007 for presenting/reviewing the Draft Final Report (see Ref. [2.6] to [2.9]).
5. RESULTS
5.1 CONCEPT DEFINITION
The concept to be analysed (see Ref. [1.2]) is based on a multistatic primary surveillance radar system
using multiple low power ground based transmitters (Tx) and multiple ground-based receivers (Rx).
The system must use either CW or pulsed waveforms and coherent processing.
Its objective is to provide detection and 3D (or 2D) target location for approach, TMA and/or En-route
applications.
Two typical coverage domains are to be analysed:
• Approach/ TMA: 50 Nm x 50 Nm,
• En-route: 150 Nm x 150 Nm.
In terms of technical objectives, one must consider the existing requirements applicable to PSR (see
Ref. [4.9]), which can be summarised as follows:
• Probability of false alarm < 20 false targets reports per antenna scan (e.g. every 4s or 5s for a
typical PSR such as STAR 2000),
2
2
• Probability of detection in the coverage area > 90% on a 1m (and 10m ) RCS targets (SW2
fluctuation),
• Accuracy:
o Range: bias < 100m, random errors (1σ) < 120m,
o Azimuth: bias < 0.1°, random errors (1σ) < 0.15°,
• Resolution:
o Range: 2 x 3dB pulse width (e.g. 300m or 400m for a typical PSR such as STAR
2000),
o Azimuth: 3 x 3dB beamwidth (e.g. 4.2° for a typical PSR such as STAR 2000),
• Availability:
o Maximum outage time < 4 hours,
o Cumulative outage time < 40 hours / year
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To complete these requirements, it is proposed to consider the following (based on the rationale
illustrated in Figure 2 to Figure 4, which are plots extracted from a TR6 database):
Approach/ TMA
En-Route
0 -10 kft
10 - 60 kft
20 - 300 m/s
100 - 300 m/s
Altitude
Velocity (airspeed)
Table 5: Proposed Complementary Definitions
The completed requirements could then be summarized in Table 6 and Figure 1 below:
Approach/ TMA
En-Route
50 Nm x 50 Nm
150 Nm x 150 Nm
Minimum Altitude
0
10 kft
Maximum Altitude
10 kft
60 kft
Minimum Velocity (airspeed)
20 m/s
100 m/s
Maximum Velocity (airspeed)
300 m/s
300 m/s
Horizontal area
Table 6: Proposed areas for the MSPSR system preliminary definition
En-Route
Vmin : 100 m/s
Vmax : 300 m/s
10 - 60 kft
Approach/ TMA
Vmin : 20 m/s
Vmax : 300 m/s
50 Nm
150 Nm
0 -10 kft
50 Nm
150 Nm
Figure 1: Proposed areas for the MSPSR system preliminary definition
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Distribution of Zmax (Liners)
100.00%
90.00%
80.00%
Probability
70.00%
60.00%
Probability
50.00%
% Cumulative
40.00%
30.00%
20.00%
10.00%
20000
19000
18000
17000
16000
15000
14000
13000
12000
11000
10000
9000
8000
7000
6000
5000
4000
3000
2000
0
1000
0.00%
ZMax (m)
Figure 2: Distribution of Maximum Altitudes (Liners)
Distribution of Vmax (Liners)
100.00%
90.00%
80.00%
Probability
70.00%
60.00%
Probability
50.00%
% Cumulative
40.00%
30.00%
20.00%
10.00%
300
280
260
240
220
200
180
160
140
120
100
80
60
40
20
0
0.00%
Vmax (m/s)
Figure 3: Distribution of Maximum Velocities (Liners)
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Distribution of VMin (Landing Liners)
100.00%
90.00%
80.00%
Probability
70.00%
60.00%
Probability
50.00%
% Cumulative
40.00%
30.00%
20.00%
10.00%
95
100
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
0.00%
Vmin (m/s)
Figure 4: Distribution of Minimum (landing) velocities (Liners)
An overview of the proposed concept is shown on Figure 5, Figure 6 and Figure 7 hereafter.
The MSPSR contains 3 main elements:
• Several Transmitters (Tx),
• Several Receivers (Rx),
• One Central Unit.
All Transmitters are used simultaneously to illuminate the target(s) and each receiver processes the
signal coming from all transmitters after reflection on the target(s).
Synchronisation between Transmitters and Receivers can be made by direct reception of the
transmitted signal or by data link (or by a combination of the two methods).
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: Tx
ATC
Centre
: Rx
Central
Unit
MSPSR
Figure 5: MSPSR General Concept
Figure 6: Principle of the MSPSR Multistatic detection
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Target Signal
Reference Signal
(Direct or Data link)
Figure 7: Principle of the MSPSR Synchronisation
The MSPSR detection is based on the elementary bistatic radars made up by each Rx/Tx pair.
For a given Rx/Tx pair, the target will give an echo with a time delay:
t ij =
Rti + Rrj
c
where :
Rti : Transmitter (i) to Target range
Rrj : Target to Receiver (j) range
c : speed of light
The points in space having the same delay tij are located on an ellipsoid, whose locus are the
transmitter and the receiver.
This means that if no other measurement is available, there is an ambiguity on the target position.
If several Rx/Tx pairs are used, the ambiguity can be removed because the target lies at the
intersection of all the corresponding ellipsoids, as it is suggested on Figure 8 (for a simpler 2D
situation).
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Tx
Rx#2
Rx#1
Target
Rx#3
Figure 8: Principle of ellipsoid intersect
The minimum number of Tx/Rx pairs is 3.
The minimum configuration is then:
• either three transmitters and one receiver,
• or one transmitter and three receivers.
When two transmitters and two receivers are used, then one can built four ellipsoids.
Because each receiver can receive the signal coming from all transmitters, it is necessary to find a way
to separate the signal of each transmitters. Several methods can be used, including the use of different
frequencies.
The location accuracy depends on the range resolution of each bistatic pair and on the geometry. The
term GDOP (“Geometric Dilution of Precision”) is used to provide the ratio between the accuracy along
one direction (for instance de x coordinate) and the elementary range resolution:
GDOPx =
σx
σr
The range accuracy is classically given by the following relationship:
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2
⎛
⎞
c
2
σ r ≈ ⎜⎜
⎟⎟ + σ floor
⎝ 2.B.k. 2.SNR ⎠
where :
c : speed of light
B : Bandwidth
k : processing dependant coefficient
SNR : Signal to Noise Ratio
σ floor : construction error
The GDOP mechanism is illustrated on Figure 9 below:
Tx
Rx#2
Rx#1
Target
Rx#3
Figure 9: Principle of GDOP
In a more mathematical approach, the optimal estimator is given by:
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X = P.H T .R -1 .Z
where :
(
P = H T .R -1 .H
)
−1
is the covariance matrix of X
H is the observation matrix
R is the measurement covariance matrix
Z is the observation (measurement)
With this representation, the GDOP (matrix) is given by:
GDOP = P.R -1
As it can be seen on detailed evaluations (see Chapter 5.3.1.3), GDOP varies smoothly when the
target is flying over the area where Tx’s and Rx’s are deployed, and increases more rapidly when the
targets leaves this area.
5.2 CONCEPT ANALYSIS
5.2.1 REVIEW OF POSSIBLE SYSTEM ARCHITECTURES
5.2.1.1 Configuration of transmitters and receivers
Several configurations can be used a priori, by varying the number of transmitters and/or of receivers.
One Tx
Multiple Rx
Multiple Tx
One Rx
Multiple Tx
Multiple Rx
Elementary Peak Power
=
+
+
Tx complexity
-
=
=
Rx complexity
+
=
=
Redundancy
-
-
=
Overall performance (detection range, accuracy…)
=
=
+
Deployment (expandable)
=
=
+
Adaptation to environment
=
=
+
Criteria
“+” indicates an advantage of the corresponding architecture for the given criteria
“-“ indicates a disadvantage of the corresponding architecture for the given criteria
“=” indicates a reference point for the given criteria
Table 7: Rx/Tx architecture comparison table
The rationale for each criteria are given below:
• Elementary Peak Power is lower for solutions with multiple transmitters, which gives them an
advantage
• Tx is more complex if only one transmitter is used, thus giving it a disadvantage,
• Rx is simpler when only one Tx is used, leading to a “+” to the case “One Tx”,
• Redundancy is better when several Tx and several Rx are used,
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•
•
Overall performance is better when several Tx and several Rx are used, in particular because
of the variety of aspects angles which reduces the risk to have a low RCS or a masking effect,
and improves the accuracy by merging (taking benefit of the most accurate measurement),
Deployment and Adaptation to environment are more flexible when both Tx and Rx can be
sited independently,
The proposed system uses multiple transmitters and multiple receivers, because it has the following
advantages:
• Low transmit power,
• Redundancy and continuous service (e.g. during maintenance),
• Performance:
o Detection (making the best use of multistatic target RCS),
o Localisation (3D capability)
o 3D instantaneous velocity vectoring (based on simultaneous multiple aspect Doppler),
• Progressive deployment::
o Rx’s may added for improving the performance with no impact on the transmission
part,
o Rx’s and Tx’s may be added for extended coverage (e.g. in a corridor),
• Adaptation to environment:
o Rx and Tx sitting may be optimised with regard to the terrain, man-made obstacles…
o Existing infrastructures (e.g. masts) may be used to install Tx and Rx,
o Rx/Tx may be moved afterwards (reconfigurable architecture) in case of new
infrastructures (e.g. buildings…)
Single Tx/ Multiple Rx would mainly suffer from the large transmit peak power which would be required.
Multiple Tx/ Single Rx would have the main drawback of the Rx complexity (in particular its necessary
antenna size).
5.2.1.2 Coverage and antenna diagrams
In terms of coverage, the envisaged system is based on omnidirectional Tx and Rx antenna patterns,
which will give the following outstanding features:
• Simultaneous looking (everywhere at the same time) will:
1
o Provide an increased, flexible and reconfigurable renewal rate (typically 1.5 s ( ),
compared to current antenna scans of 4-5 s),
o Give a better flight path assessment/ prediction (e.g. in case of manoeuvre),
o Provide a reduced reaction time (in case of anti-intrusion mission).
• Possibility of increased and flexible performance thanks to Long Term Integration,
• Robustness and reduced maintenance (no rotating parts).
However, there remains some open issues with this type of architecture, but recent advances in other
domains allow to envisage smart solutions to these issues. They are mainly:
• The separation at Rx level of target signal coming from different Tx; this can be solved by
using either frequency/code separation at Tx level and/or Doppler processing at Rx level,
• The separation at Rx level of target signal and reference signal (for a given Tx); DBF and/or
Doppler are smart answers to this issue
• The data association complexity (multiple Tx, multiple target situation): this can be solved by
using some angular resolution at the Rx level and also a shared processing architecture (each
Rx being in charge of the extraction of targets in its domain of detection, and the central unit
doing fusion of elementary Rx detections).
1
This renewal rate assumes that each receiver proceeds to a cyclic processing of 3 transmitters, each
with a 500 ms integration time.
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5.2.1.3 Waveforms
Radar waveforms can be roughly split into two broad categories:
• Pulsed waveforms,
• CW waveforms
Pulsed waveforms can be:
• Non modulated,
• Modulated (e.g. Linear FM, Non Linear FM, PSK…) or non modulated,
CW waveforms can be:
• Non modulated,
• Periodically modulated (e.g. FMCW, PSK…),
• Noise like (amplitude and phase, phase only, frequency only…),
• Multi-tone (equistep, sparse, OFDM…).
For a multistatic radar, and when it is possible, one prefers to use CW waveforms, because they allow
to reduce the constraint on the transmitter (because it can work with a 100% duty factor, thus it can
use a low peak power),
For the purpose of this study, one analyse more deeply 3 types of CW waveforms, based on their
potential interest and also on their TRL (Technical Readiness Level):
• FMCW,
• Noise,
• Multi-tone
In order to show the various properties of these waveforms, one first defined a set of initial constraints
for the MSPSR system:
• Range ambiguity (if any) > 50 Nm
o for operational constraints (area to be covered 50 Nm x 50 Nm),
o to optimize the performance by avoiding clutter folding over,
o to simplify the receiver by avoiding range ambiguity processing
•
Range resolution < 150m (thus bandwidth > 1 MHz)
o a small range resolution will improve the detection by reducing the clutter resolution
cell, but hardware (and cost) constraints do not allow to have large bandwidth,
•
Doppler ambiguity (if any) > +/- 300 m/s
o for operational constraints (maximum velocity: 300 m/s),
o to optimize the performance by avoiding low velocity clutter folding over,
o to simplify the receiver by avoiding Doppler ambiguous processing
•
Doppler resolution < 1 m/s (integration time = 500ms)
o For having a good target separation together with a high coherent processing gain, but
with a reasonable integration time (not too long in order for the target to stay within one
range “gate” during the coherent integration time and thus avoiding more complex
range migration processing).
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Criteria
Range ambiguity
FMCW
Bandwidth B,
Period Tr
Multi-Tone
Bandwidth B,
Freq. step b
Noise
Yes (C.Tr/2)
Yes (C/2.b)
No
[Tr > 667 μs]
[b < 1.5 kHz]
Yes (λ.Fr/2)
Velocity ambiguity
[525 m/s for Fr = 1/Tr = 1.5 kHz]
Adjustable
Sidelobe
Doppler sensitivity
Adjustable
(Trade-off with
resolution)
1/(B.Tint)
(Trade_off with
resolution)
Yes
No
Yes
Table 8: Waveform comparison table
The next figure illustrates the ambiguity functions for the 3 waveforms, with B=1 MHz and T=Tr=667 μs
(thus the Doppler resolution is not significant for this example).
Figure 10: Ambiguity functions (FMCW -left-, Noise -middle-, Multi-tone -right-)
All these waveforms are candidates for the MSPSR system, with some arguments in favour of Noiselike (because it is insensitive to Range and Doppler ambiguity) or Multi-Tone (because it is flexible in
terms of frequency allocation).
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5.2.2 FREQUENCY ALLOCATION ISSUES
5.2.2.1 Choice of UHF band
New radar techniques such as DBF and digital reception are mature especially in low frequency (e.g. in
UHF) and also more affordable (e.g. because less antenna elements can be used, leading to a
reduced overall cost).
An attractive property of this system is that it requires a limited transmit power (typically 500W per
transmitter).
This can be obtained thanks to recent advances in the technological domains of low frequency bands
such as UHF (300 MHz - 1 GHz) , and more precisely thanks to the possibility to apply advanced
techniques like real time omnidirectional Digital Beam Forming and Multi-Channel Coherent Range *
Doppler processing. This makes these “software radar” techniques now affordable for low frequencies.
Indeed, the complexity of such systems directly depends on the number of receiver antenna elements,
2
which, for the same radar budget, is proportional to F (where F is the carrier Radio Frequency). For
instance, UHF compared to S-Band requires about 50 times less elements.
UHF also offers advantages compared to higher bands (e.g. L to X) for its specific propagation
properties:
• reduced atmospheric losses (see Figure 11),
• ground and rain clutter low reflectivity (see Figure 12),
• low altitude detection capability by diffraction effect, as illustrated on Figure 13 for two radars
designed with the same operational requirements (detection range and renewal rate),
Figure 11: Atmospheric attenuation (according to Ref. [4.1])
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Figure 12: Rain (left) and Ground (right) clutter reflectivity (according to Ref. [1.2])
Figure 13: Low altitude detection compared capabilities UHF (left) & X-band (right)
UHF band thus appears as a favourite candidate for defining the MSPSR system.
5.2.2.2 UHF Frequency allocation issues
The ITU, in its role of organizing the regulation of the radiofrequencies, gives the following definitions:
Term
Definition
ITU Ref.
Radiolocation
Radiodetermination used for purposes other than those of
radionavigation
RR 1.11
Radiodetermination
The determination of the position, velocity and/or other
characteristics of an object, or the obtaining of information
relating to these parameters, by means of the propagation
properties of radio waves
RR 1.9
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Term
Definition
ITU Ref.
Radionavigation
Radiodetermination used for the purposes of navigation,
including obstruction warning
RR 1.10
Aeronautical
Radionavigation Service
A radionavigation service intended for the benefit and for
the safe operation of aircraft
RR 1.46
Radionavigation Service
A radiodetermination service for the purpose of
radionavigation
RR 1.42
Radiodetermination
Service
A radiocommunication service for the purpose of
radiodetermination
RR 1.40
Radiocommunication
Service
ITU-R Rec. V.573 - A service as defined in the RR
involving the transmission, emission and/or reception of
radio waves for specific telecommunication purposes.
RR 1.19
Table 9: ITU Terms and Definitions (extracts)
These definitions may be seen as a taxonomy such as presented below:
Radiodetermination
Radionavigation
Aeronautical Radionavigation
Radiolocation
(Other categories)
Figure 14: ITU Taxonomy of “Radiodetermination” Services
Surveillance Systems such as PSR traditionally belong to the “Aeronautical Radionavigation Service”
category of the ITU. It is then natural to assume that MSPSR will too.
It is thus worthwhile to examine what are the current frequencies allocated to this service. Figure 15
below shows the frequency slots currently allocated within the UHF/S/L Bands:
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S
1 slot =
50 MHz
2000-2500
2500-3000
3000-3500
3500-4000
1000 - 1200
1200 - 1400
1400 - 1600
1600 - 1800
1800 - 2000
300 - 400
400 - 500
500 - 600
600 - 700
700 - 800
L
1 slot =
20 MHz
UHF
1 slot =
10 MHz
: Aeronautical Radionavigation (Primary)
800 - 900
: Aeronautical Radionavigation (Secondary)
900 - 1000
: Broadcasting
Figure 15: Frequencies allocated to Aeronautical Radionavigation services (UHF/S/L Bands)
Table 10 gives a more precise list for some typical Radionavigation systems. It can be seen that, for
example, the low UHF slot (328.6 MHz to 335.4 MHz) is dedicated to the ILS Glide Slope systems.
Radionavigation System
Frequency Band
Loran-C
90 kHz to 110 kHz
Omega
10.2 kHz; 11.33 kHz; 13.6 kHz
VOR
108 MHz to 118 MHz (by 100 kHz steps)
DME
960 MHz to 1213 MHZ (bands separated by 1 MHz)
TACAN
960 MHz to 1213 MHZ
108 MHz to 112 MHz (Localizer)
ILS
328.6 to 335.4 MHz (Glide Slope)
75 MHz (Marker Beacons)
5 GHz to 5.25 GHz (Angle)
MLS
0.86 GHZ to 1.215 GHZ (Ranging by DME)
15.5 GHz to 15.7 GHz (Option)
Transit
150 MHz and 400 MHz (satellite broadcasting)
Aeronautical Radiobeacons (NDB)
190 kHz to 415 kHz and 510 kHz to 535 kHz
Maritime Radiobeacons
285 kHz to 325 kHz
GPS
1575.42 MHz (L1) carrying a 2.046 MHz bandwidth (SPS)
1227.6 MHz (L2) carrying a xxx MHz bandwidth (PPS)
Maritime DGPS
See GPS + Maritime Radiobeacons
WAAS (1)
See GPS + GEO satellites broadcast
VTS
See US Coast Guards
(1): Aeronautical GPS Wide Area Augmentation System
Table 10: Radionavigation Systems (Frequency Bands)
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If we extend the definition of the system which is under investigation, and in particular if we consider
that, beyond its role in the safe operations of aircraft, it could also provide information for security
purposes such as:
• surveillance of surface movements,
• anti-intrusion (e.g. non civil aircraft),
then, it could be attempted to put this system in the “Radiolocation” category.
The frequencies allocated to this Radiolocation category is summarized on Figure 16 below:
S
1 slot =
50 MHz
2000-2500
2500-3000
3000-3500
3500-4000
1000 - 1200
1200 - 1400
1400 - 1600
1600 - 1800
1800 - 2000
300 - 400
400 - 500
500 - 600
600 - 700
700 - 800
L
1 slot =
20 MHz
UHF
1 slot =
10 MHz
: Radiolocation (Primary)
: Radiolocation (Secondary)
800 - 900
900 - 1000
: Broadcasting
Figure 16: Frequencies allocated to Radiolocations services (UHF/S/L Bands)
The low UHF frequency slot allocated to Radiolocation as a primary service (shared with “Amateur”
and “Amateur Satellites” services) is 430 MHz to 440 MHz.
Depending on the category (Aeronautical Radionavigation or Radiolaction), and provided, of course,
that the envisaged system can share the frequencies with existing systems, then one can consider that
there are two possible low UHF slots of approximately 10 MHz width:
• 328.6 MHz to 335.4 MHz (currently used by ILS Glide Slopes),
• 430 MHz to 440 MHz.
Another point is the now well known “Spectrum Dividend” of the digital broadcasting which should free
a part of the current band allocated to the “Broadcasting” services (470 MHz to 862 MHz), such as
illustrated on Figure 15 and Figure 16.
A transition period from mid 2006 to mid 2015 will allow the progressive installation of digital
broadcasting system. At the end of this transition period, it is expected that about 300 MHz could be
freed within this 470-862 MHz band.
Regarding the MSPSR bandwidth requirement, the analysis shows that transmission should be made
with 1 MHz bandwidths for each transmitter. In order to avoid interferences, each transmitter central
frequency would be separated from another by about 2 MHz, as illustrated below:
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Tx #3
Tx #N-1
Tx #2
1 MHz
Tx #N
Tx #1
Frequency
2 MHz
Figure 17: A possible MSPSR transmission frequency scheme
On the basis of the elementary cell presented above, and for transmitters and receivers supposed
installed on masts 30m above the ground, the number of transmitters which can be “seen” by each
receiver is about 6. For taking in account of the terrain and propagation, one should take a margin and
consider rather a maximum number of 12 transmitters.
This implies that a 25 MHz band would be required for the system.
An extension of the low UHF band (say from 470 MHz up to 495 MHz) to the Radiolocation and/or the
Aeronautical Radionavigation service(s) would obviously allow the deployment of MSPSR systems in a
more efficient way (meaning better performance, and in particular in terms of accuracy and resolution)
and a less stringent situation (meaning with less constraints with regards to existing equipments).
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5.2.3 PARAMETRIC PERFORMANCE PREDICTION
The performance prediction of multistatic systems is more complicated than for monostatic systems,
and rapidly depends on the geometrical configuration.
It is then more efficient to rely on simulations to proceed to more complete investigations and
parametric analysis.
This is the reason why simulation is used, in order to:
• Define the scenario:
o Tx and Rx network (number and location of each Tx and each Rx)
o Tx parameters:
Peak Power,
Antenna Gain,
Coverage (Az, El)
Polarisation,
Carrier Frequency,
Bandwidth,
System Losses.
o Rx parameters:
Antenna Gain (on Target),
Antenna Rejection (on Tx),
Antenna 3dB beamwidth in azimuth,
Antenna 3dB beamwidth in elevation,
Bandwidth,
Receiver Noise Factor,
Processing Integration Time,
Range Processing Side Lobe Level,
Doppler Processing Side Lobe Level,
Range * Doppler Processing Intercardinal Side Lobe Level,
Doppler Rejection of fixed targets
System Losses,
Probability of False Alarm,
Measurement error floors (Range, Doppler, Azimuth, Elevation)
o Environment parameters:
Type of surface environment,
Type of atmospheric environment.
o Type and limits of coverage (horizontal plane, vertical plane, time history),
o Target parameters:
Size,
Mean RCS,
Type of fluctuation.
• Compute the various features:
o For each Tx-Target-Rx:
Paths (Direct and Reflected),
Antenna gains in necessary directions (target, transmitter), for both direct and
reflected paths,
Signal,
Interferences (Direct Path, Ground Clutter, Rain Clutter, Thermal Noise),
Signal-to-Interference,
Probability of Detection,
Measurement errors (Range, Doppler, Azimuth, Elevation)
o For the Central Unit:
System Probability of Detection,
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•
Measurement errors after fusion of all elementary results
Display results:
o Network configuration,
o Technical data (Elementary Doppler velocity maps, Interference levels, SIR maps…)
o Probability of detection maps and accuracy maps.
2
An example of such simulation ( ) is given hereafter for a simple bistatic situation:
Figure 18: Simple Bistatic situation (left) and assessment grid (right)
Rx
Tx
Figure 19: Example of Bistatic coverage (horizontal plane, UAV at 1000m AGL)
2
All results are obtained with a round earth model. The assessment grid (blue dots for either horizontal
or vertical planes, red dots for time history) shows the points in space where the performance is
evaluated.
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Figure 20: Example of bistatic coverage (vertical plane)
An omnidirectional UHF transmitter (Tx) using a vertically polarised CW waveform is located 30m
above the surface.
An omnidirectional UHF receiver (Rx) using a DBF antenna also 30m above the ground is located
30km away from the transmitter.
2
A 1m SW1 target is considered, with propagation effects simulated on a round earth model. Reflection
coefficients correspond to a “Standard Soil” condition.
Clutter is not simulated.
On both coverages, one plots the Probability of Detection. Its value is colour-coded between 0 and 1.
Figure 19 illustrates several phenomena:
• the decay of the Probability of Detection with range, as usually in radar detection,
• the shape of probability contours, which corresponds to the ovals of Cassini in this bistatic
configuration,
• the slow and periodic variations which are an effect of the interferences with the ground
(multipath effect),
• the attenuation in the transmitter-receiver direction, which is due to the cancellation (Spatial
filtering) of the direct signal by the receiver,
This last effect results from the rejection in the Tx direction, in order to avoid a saturation of the
receiver. In this simulated case, it is obtained through a cancellation applied with the DBF antenna.
The multipath effect is even more easily seen on the vertical coverage (Figure 20), where fringes are
clearly visible.
The reduction of coverage at the zenith of both Rx and Tx is due to the antenna diagrams (Tx has a
simple antenna with a “cos” shaped diagram, and Rx is using a DBF antenna made up of elementary
sources having also a “cos” shape).
The effect of various clutters is illustrated by comparing the vertical coverages shown below:
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Figure 21: Coverage with various clutter: no clutter(tr), ground(tl), rain(bl), ground+rain(br)
For these cases, the target is flying at constant altitude, constant speed (180 m/s) and constant
heading (270° -to the west-).
2
It must be reminded that this case is especially difficult because the target has a low RCS (1 m ).
For completeness, the rain clutter parameters which are simulated are as follows:
• Maximum Altitude: 3750 m
• Maximum Velocity: 15 m/s
• Heading: 270°
• Average precipitation rate: 4 mm/h
• Velocity spread standard deviation: 3 m/s
• Wind Shear: 4 m/s/km
It is observed that the coverages are almost the same, indicating that the receiver processing is robust.
In order to analyse the Doppler effect, one can compare, on Figure 22, the different Doppler velocities:
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Figure 22: Doppler velocities: target (top), rain maximum value(bl), rain minimum value (br)
Two values are to be considered for rain clutter because of the wind shear. It can also be seen that the
rain clutter is limited in altitude because of the rain maximum height and the Rx antenna directivity in
elevation.
Another way to understand these effects is to analyse the various interference levels, in terms of
“residue” (the interference energy which remains in the target resolution cell). In order to correctly
interpret these values, it is important to have in mind the Doppler difference between target and
interference:
• direct signal and ground clutter residues are 0 m/s spectral lines,
• rain clutter is moving (because of the average velocity) and has a spread spectrum (because
of the wind shear).
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The various residues are shown on Figure 23 below:
Figure 23: Interference residues: direct path(tl), ground clutter(bl), rain clutter(br)
On this figure, it can be seen that all residues are almost cancelled (their level being below thermal
noise)
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5.3 PRELIMINARY DEFINITIONS
5.3.1 APPROACH CONFIGURATION PRELIMINARY DEFINITION
5.3.1.1 MSPSR Elementary Cell
The envisaged configuration for the Approach mission relies on an elementary configuration, called a
“MSPSR elementary cell”, designed in the objective of being an elementary “building block” which can
be re-used for expanding the coverage as needed.
The elementary cell contains 3 Tx and 3 Rx, and is designed in order that:
• it may be repeated in all directions by duplication,
• each Rx can use three close-in Rx in order to allow 3D triangulation,
• each Tx may be used by 3 close-in Rx in order to have an increased sensitivity and location
accuracy.
Transmitters and Receivers of all adjacent cells will be shared in order to get the optimal performance
in terms of coverage and accuracy.
Figure 24 shows the geometry of the proposed MSPSR cell, which is based on a 30 km baseline (the
baseline is the distance between one Tx and one of its surrounding Rx.
This geometry results from an optimisation (taking also cost consideration into account) in which one
extended as much as possible the cell baseline while maintaining a sufficient detection/ accuracy
2
coverage for the most stringent case (1 m target).
Figure 24: MSPSR Cell
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In order to scale the MSPSR cell, one has superimposed, on Figure 24, a plan of the Roissy-Charles
de Gaulle airport area over the cell configuration.
This elementary cell corresponds to the Approach/TMA required coverage (50 Nm x 50 Nm).
The coverage will depend of course on the Tx’s and Rx’s locations, but it can sustain variations of
some km to cope with terrain constraints.
5.3.1.2 Tx and Rx characteristics
One MSPSR cell is made up of 3 Tx and 3 Rx, having the following characteristics:
Feature
Peak Power
Antenna Gain
Value
Comments
500 W
Allows coverage compliance with 30 km baseline
2 dBi
Corresponds to an simple quarter wave antenna
Polarisation
Vertical
Allows a simple design and reduces ground
reflections
Bandwidth
1 MHz
Required for target location accuracy
System losses
1.5 dB
Losses between transmitter and antenna
Table 11: Tx characteristics
Feature
Value
Comments
Antenna gain (on target)
10 dBi
Achievable with a simple and compact design
(e.g. eight elements)
Antenna gain (on Tx)
-40 dBi
idem
Corresponds to one sector (8 elements
antenna)
Azimuth 3dB beamwidth
45°
Elevation 3dB beamwidth
“Cos”
Corresponds to dipoles
Bandwidth
1 MHz
See Table 11
Noise Factor
3 dB
Integration time
500 ms
Standard value in UHF band
Trade-off between processing gain and range
migration
Range Processing SLL
35 dB
Standard value
Doppler Processing SLL
50 dB
Idem
Range x Doppler Intercardinal Processing
SLL
80 dB
Doppler Rejection of fixed targets
80 dB
Idem
System Losses
2 dB
Idem
SLL Processing losses
2 dB
Idem
Pfa
-6
3.10
Range error floor
5m
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Feature
Value
Comments
Azimuth error floor
15°
Uniform error on one 45° sector
Elevation error floor
NA
No elevation measurement
Doppler error floor
0.5 m/s
Standard value
Table 12: Rx characteristics
5.3.1.3 Results
Three types of results are presented, for three different types of targets:
Target Type
UAV
3m
Business Jet
Liner
Size
10 m
30 m
Mean RCS
0 dBm
2
Fluctuation
SW1
10 dBm
2
SW1
20 dBm
2
SW1
Table 13: Typical targets
In the above table, the “size” corresponds to the target typical dimension (e.g. the fuselage length), and
is used to introduce an accuracy limit (indeed, a primary radar uses the reflection on the target and
depending on the aspect angle, the electro-magnetic “centre” may move from one position (e.g. the
cockpit) to another (e.g. an engine)). It is considered as a random error having a uniform distribution on
the target size for all spatial dimensions (x, y and z).
“SW1” fluctuation means that for each elementary detection process (which uses one Tx/Rx pair), it is
assumed that the target fluctuates according to this model. This is a conservative hypothesis because,
to get a high probability of detection, this model requires a larger SNR (compared to SW0 and to
SW3), for a given Probability of false alarm.
“SW2” is not used as long as there is no frequency diversity for a given Tx/Rx pair.
Detections from each Tx/Rx pairs are assumed independents, and a cumulative probability is
computed from all elementary Tx/Rx detection probabilities.
Because one needs at least 3 Tx/Rx pairs for getting a 3D detection, the so-called “System Probability
of Detection” is defined as the probability that at least 3 Tx/Rx pairs detect the target
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The following results are presented hereafter:
Type of scenario and analysis
Type of
results
Horizontal
Coverage
(Z = 100 m)
Horizontal
Coverage
(Z = 1000 m)
Vertical
Coverage
Mean PoD
System PoD
Figure 26
Figure 28
Figure 30
XY & Z
Accuracies
Figure 27
Figure 29
Figure 31
Mean PoD
System PoD
Figure 32
Figure 34
Figure 36
XY & Z
Accuracies
Figure 33
Figure 35
Figure 37
Mean PoD
System PoD
Figure 38
Figure 40
Figure 42
XY & Z
Accuracies
Figure 39
Figure 41
Figure 43
Target
UAV
RCS 1 m
2
Bizjet
RCS 10 m
2
Liner
RCS 100 m
2
Table 14: Table of scenarios
Four kinds of results are shown, corresponding to maps drawn in either horizontal or vertical planes:
•
Mean PoD, which is calculated as the mean of elementary probabilities of detection from each
Tx/Rx pair,
•
System PoD (see above),
•
Horizontal accuracy, calculated as
σ H = σ X 2 +σY 2
, where σX and σY are the standard
deviations in X and Y,
•
Vertical accuracy, corresponding to
σZ
3
( ).
Accuracy results correspond to “plot” level data. An analysis of the “system” accuracy (after plot
filtering) is given in Chapter 5.3.1.3.4.
3
It is recommended to take care of the different scale between Horizontal accuracy (0 to 100m) and
Vertical accuracy (0 to 1000m)
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The assessment grids are given below:
Figure 25: Assessment grids: Z=100m (top left), Z=1000m (top right), Vertical (bottom)
All results are presented for the worst case:
• ground multipath,
• ground clutter + rain clutter.
Target kinematics and rain parameters are the same as above (see 5.2.3).
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2
5.3.1.3.1 UAV (1 m RCS)
Figure 26: UAV, Horizontal Coverage, 100m , Mean PoD (left) & System PoD (right)
Figure 27: UAV, Horizontal Coverage, 100m, XY Accuracy (left) & Z Accuracy (right)
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Figure 28: UAV, Horizontal Coverage, 1000m, Mean PoD (left) & System PoD (right)
Figure 29: UAV, Horizontal Coverage, 1000m, XY Accuracy (left) & Z Accuracy (right)
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Figure 30: UAV, Vertical Coverage, Mean PoD (left) & System PoD (right)
Figure 31: UAV, Vertical Coverage, XY Accuracy (left) & Z Accuracy (right)
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5.3.1.3.2 Bizjet (10 m RCS)
Figure 32: Bizjet, Horizontal Coverage, 100m , Mean PoD (left) & System PoD (right)
Figure 33: Bizjet, Horizontal Coverage, 100m, XY Accuracy (left) & Z Accuracy (right)
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Figure 34: Bizjet, Horizontal Coverage, 1000m, Mean PoD (left) & System PoD (right)
Figure 35: Bizjet, Horizontal Coverage, 1000m, XY Accuracy (left) & Z Accuracy (right)
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Figure 36: Bizjet, Vertical Coverage, Mean PoD (left) & System PoD (right)
Figure 37: Bizjet, Vertical Coverage, XY Accuracy (left) & Z Accuracy (right)
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5.3.1.3.3 Liner (100 m RCS)
Figure 38: Liner, Horizontal Coverage, 100m , Mean PoD (left) & System PoD (right)
Figure 39: Liner, Horizontal Coverage, 100m, XY Accuracy (left) & Z Accuracy (right)
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Figure 40: Liner, Horizontal Coverage, 1000m, Mean PoD (left) & System PoD (right)
Figure 41: Liner, Horizontal Coverage, 1000m, XY Accuracy (left) & Z Accuracy (right)
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Figure 42: Liner, Vertical Coverage, Mean PoD (left) & System PoD (right)
Figure 43: Liner, Vertical Coverage, XY Accuracy (left) & Z Accuracy (right)
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5.3.1.3.4 Analysis
The various scenarios presented here above show that the proposed system has the capability to
provide the required coverage in terms of Probability of Detection, for targets flying above the area
covered by the MSPSR cell.
2
The system is optimised for the most stringent case (UAV: 1m RCS); one observes that the coverage
2
2
is improved for target having a larger RCS (Bizjet: 10m , Liner: 100m ).
The detection results can be summarized as follows:
Maximum Detection
Height
UAV
Bizjet
Liner
30 kft
60 kft
> 60 kft
Table 15: Summary of detection performance
Regarding the accuracies, its is reminded that the results obtained here correspond to plot level
accuracies, which means data obtained every 1.5 s in the case of the proposed system. After filtering,
these accuracies will be improved.
nd
4
For instance, if we consider a conventional 2 order filter (meaning constant velocity model ( )) with a
30s time constant (which correspond to an integration on 20 consecutive “plots”), the gain on the
estimated position accuracies is about 0.45 (in standard-deviation units). One can thus easily derive
the accuracy after filtering from plot accuracy and supposed bias (which depends in particular on the
target size).
The accuracy results are given in the next tables:
XY Accuracy
UAV
(Z < 30 kft)
Bizjet
(Z < 60 kft)
Liner
(Z < 60 kft)
Plot Level
50 m
25 m
20 m
After filtering
25 m
15 m
15 m
Z Accuracy
(Z > 3000 ft)
UAV
(Z < 30 kft)
Bizjet
(Z < 60 kft)
Liner
(Z < 60 kft)
Plot Level
1000 m
500 m
300 m
After filtering
500 m
250 m
150 m
It is noticeable that the Z accuracy improves when altitude increases.
The resolution will be obtained with the following features:
• Bandwidth,
• Doppler,
• Angle (Azimuth).
4
Which is a rather conservative hypothesis (in particular because it does not take into account the
velocity measurement from the Doppler).
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The 1 MHz bandwidth gives a 3dB bistatic range beamwidth of about 150m for each Tx/Rx pair. The
geometry between all Tx’s and Rx’s will lead to an equivalent XY 3 dB beamwidth of about 150m.
The resolution between two identical (point) targets (having the same RCS) both having an elementary
SNR of at least 22 dB is expected to be about 400m, with a probability of at least 80%.
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5.3.2 EN-ROUTE CONFIGURATION PRELIMINARY DEFINITION
For the En-route application (150 Nm x 150 Nm), two methods can be envisaged if one tries to make
profit of the existing equipments supposed deployed for an Approach application:
•
•
Solution 1: re-using the elementary cells already defined for the Approach application,
Solution 2: using variants to the Approach configuration.
5.3.2.1 Solution 1 (Re-use of Approach configuration)
5
Because the configuration which is defined for the Approach application has already the capability ( )
to detect targets up to 30 kft (UAVs) and 60 kft (Bizjets, Liners), it is tempting to re-use this
configuration to fulfil the requirement for the En-route application in terms of maximum altitude. In this
case, one has to deploy as many cells as required to fulfil the requirements in terms of area to control.
A direct application shows that covering a 150 Nm x 150 Nm would require 9 elementary cells.
However, it is not certain that the full 150 Nm x 150 Nm is to be controlled. If only parts of it (e.g. areas
corresponding to airways) are of interest, then MSPSR cells could be deployed only in these areas.
The limitation of this solution is that its effective coverage roughly corresponds to the volume above the
deployed cells, which prevents its use to control targets in region where no equipment can be installed
(e.g. oceans).
In order to evaluate the capability of one MSPSR cell alone in terms of En-route detection, one has
plotted the vertical coverage on a +/- 75 Nm around one cell (supposed deployed for the purpose of an
2
Approach mission), for a Liner (100 m RCS). Figure 44 shows the coverage grid used for assessing
the performance. It covers the en-route altitudes (3000m to 20000m) and ranges (+/- 75 Nm) -see 5.1-
Figure 44: En-route coverage grid
5
see 5.3.1.3.4
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Figure 45 and Figure 46 show the performance. One will pay attention to the scales, which are different
between vertical and horizontal axis.
Figure 45: Liner, En-route Vertical Coverage, Mean PoD (left) & System PoD (right)
Figure 46: Liner, En-route Vertical Coverage, XY Accuracy (left) & Z Accuracy (right)
It appears that one MSPSR cell is able to provide the detection for a En-route mission on Liners, when
the aircraft is going to fly over the cell.
To get a more detailed view of this performance, one can analyse the time history presented hereafter,
for a Liner flying at a constant altitude of 20000m and with a speed of 180 m/s (flying to the west). The
time history is computed every 10s.
Figure 47 represents the trajectory, Figure 48 and Figure 49 show the performance.
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Figure 47: En-route time history
Figure 48: Liner, En-route time history, Mean PoD (left) & System PoD (right)
Figure 49: Liner, En-route time history, XY Accuracy (left) & Z Accuracy (right)
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This confirms the capability to achieve a correct en-route detection of a Liner with only one MSPSR cell
designed for the Approach, and shows that the accuracies are better than 250m in XY and better than
1000m in Z (with a drastic improvement when the aircraft is flying over the cell).
5.3.2.2 Solution 2 (Variants to Approach configuration)
If one wants to extend the coverage beyond the area where equipments are deployed, then one must
either modify the components or add new component(s) to the system defined for the Approach
application.
The objective would be to increase the detection range (and to maintain the accuracy) beyond the area
normally covered by the Approach system.
One can think to different methods:
• Solution 2.1: using the Approach system in a coherent way,
• Solution 2.2: using the existing receivers and adding a powerful transmitter
5.3.2.2.1 Solution 2.1 (Coherent transmission and reception)
In theory, one could use coherent transmission from all transmitters, by voluntarily using the same
frequency and choosing the phase in order to have coherent additive electric field at the desired
position in space. This would be similar to electronic beam steering where one focus the energy in one
given direction.
In the same way one could coherently process all the received signal in order to get a coherent DBF
gain from all receivers.
However this solution has drawbacks:
• transmitters are spatially distributed and are separated by a very large distance compared to
wavelength, which would be equivalent to a very sparse transmission array, thus having poor
sidelobes and many grating lobes, leading to spatial ambiguities,
• in the same way, one will also have an equivalent sparse receiving array,
• renewal rate will be reduced because one will have to focus in all direction in a sequential way,
• data flow must be dramatically increased between receivers and Central Unit, and Central Unit
processing must be dramatically increased.
This solution, although attractive from a theoretical perspective, is unlikely to be achievable in the near
future due to technological limitations.
However It can be considered as a possible field of improvement of an existing system deployed for an
Approach application.
5.3.2.2.2 Solution 2.2 (Additional transmitter)
This solution could also be split in two sub-cases:
• Omnidirectional transmitter,
• Directional transmitter, using:
o Either a cylindrical antenna (e.g. with solid state transmitters),
o Or a rotating antenna (e.g. a planar antenna with a solid state transmitters or a
reflector antenna with a magnetron).
The main drawback of such solutions, apart from the cost, would be that it would provide a limited
angular accuracy and resolution.
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To summarize the different solutions for the possible variants, one can state that several possibilities
exist which would provide the necessary detection range, but angular accuracy and resolution would
remain limited.
In conclusion, the recommendation for the En-route application is to use the elementary cells already
designed for the Approach, and to optimize their deployment in order to control the necessary area.
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5.3.3 INTERFACES AND CONSTRAINTS
5.3.3.1 Interfaces
Each component of the MSPSR (Central Unit, Rx and Tx) interfaces with an existing infrastructure. A
description of these interfaces is given in Table 16 and Table 17 below:
Central
Unit
Mechanical
Electrical
Communication
Logical
Central Unit preferably housed in an existing
building (e.g. ATC Centre)
Power Line
(1 kVA)
Ethernet link
(< 100 Mbit/s)
ASTERIX
(see details
in Table
17)
Power Line
(1 kVA)
Ethernet link
(< 100 Mbit/s)
Standard
Power Line
(5 kVA)
Ethernet link
(< 10 Mbit/s)
Standard
Rx Antenna and Rx RF Box to be fixed on top of
existing mast.
Rx
Rx Processing Box to be installed near the base
of the mast.
The mast should support cables between RF Box
and Rx Proc. Box (Gbit Ethernet).
Tx Antenna to be fixed on top of existing mast.
Tx Box to be installed near the base of the mast.
Tx
The mast should support cables between Tx Box
and Tx Antenna (coaxial cables and Ethernet
link).
Table 16: Interfaces with the existing infrastructure
From ATC Centre to Central Unit
•
Synchronization data (date)
•
Data renewal rate
•
Status request
•
Target data messages ( ):
From Central Unit to ATC Centre
6
o
Date
o
State Vector (Position, Velocity)
o
Quality
•
BITE Alarms
•
Status (on request)
Table 17: Logical data exchanges between Central Unit and ATC Centre
6
Up to 500 target data per “scan” (1.5s)
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5.3.3.2 Constraints
5.3.3.2.1 General constraints
The main constraints are summarized below:
• System:
o The deployment is dependent on the availability of UHF frequencies (see 5.2.2.2)
o The implantation is to be planned and prepared in advance in order to have the best
coverage. This can be done with a “sitting tool” using all available data (digital terrain
map, EM environment, detection performance models…), completed by an on-site
survey,
o ATC Centre upgrades are recommended for making the best use of MSPSR (e.g.
higher renewal rate, 3D…).
• Central Unit:
o It is preferably installed in the building housing the ATC Centre.
o No screen is used at Central Unit level, all MMI action is supposed done at the ATC
Centre level.
• Rx:
o Must be installed in several sites (typically 3 for an Approach configuration), separated
from each other by some 10’s of kilometers.
o Their Antenna must be elevated by about 30m above the local ground level.
o Mast, Power Line and Communication links are supposed available (see Table 16)
• Tx:
o (same constraints as Rx).
o Must be installed according to EM radiation regulations.
5.3.3.2.2 Constraints specific to mountainous regions
Optimising the site of a radar may be a complex task in difficult terrain such as mountains. This is
illustrated below for the case of a valley (altitude about 700m ASL) surrounded by 2000m+ mountains.
An airport is in the valley, and one wants to detect the traffic in the vicinity of the airport, together with
the approach traffic.
The Figure 50 is an example of:
• a site LA (“Low Altitude”) optimised to cover the valley (> 100 m AGL),
• a site HA (“High Altitude”) optimised to cover the Approach (> 4000m ASL).
Figure 50: Visibility of a LA sited Monostatic Radar (left: 100m AGL, right: 4000m ASL)
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Figure 51: Visibility of a HA sited Monostatic Radar (left: 100m AGL, right: 4000m ASL)
It is clear that the LA site does not allow the Approach, and conversely for the HA site, which does not
cover the Valley.
In general the solution will be a compromise, and the conclusion could be in some cases to deploy two
or more radars.
Compared to a conventional PSR, the MSPSR has more degrees of freedom which can be used to
optimise the coverage, because one can site the Tx’s and Rx’s with regard to the environment.
This is illustrated with the following example, which does not correspond to the proposed MSPSR
configuration, but, for the sake of simplicity, only integrates 4 elements (2 Tx and 2 Rx).
One Tx (Tx#1) and one Rx (Rx#1) are sited at low altitude and the others (Tx#2 and Rx#2) are sited at
high altitude. In this case one can have 4 bistatic combinations:
• Tx#1 with Rx#1,
• Tx#1 with Rx#2,
• Tx#2 with Rx#1,
• Tx#2 with Rx#2,
The rule which is used for this (oversimplified) example is that one needs at least one Tx/Rx pair for
detecting a target.
The corresponding multistatic coverages which are obtained with this rule are plotted on Figure 52:
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Tx#1
Tx#2
Rx#2
Rx#1
Figure 52: Visibility of a Multistatic Radar (left: 100m AGL, right: 4000m ASL)
It can be seen that both the Valley and the Approach are covered with such a system.
However, the true constraint of a MSPSR is that it needs at least 3 Tx-Rx pairs (e.g. one Tx and 3 Rx,
or 3 Tx and one Rx) to perform a complete (3D) target location. This means that the target must be
visible by at least four Tx or Rx elements (and that among these elements, at least one if different from
the others).
If one takes a simple example of a virtual “staircase” terrain, one could deploy the following system:
Tx #2
Tx #1
Rx #1
Rx #2
Tx #4
Tx #3
Rx #3
Rx #4
Figure 53: A schematic example of deployment in a mountainous region
On this example, low altitude targets in the “Valley” are detected by Tx#4 with Rx#2, Rx#3 and Rx#4,
and low altitude target on the “Hill” are detected by Rx#1 with Tx#1, Tx#2 and Tx#3.
High altitude targets are detected by all the possible combinations.
For this example, one would need:
• 4 Tx, 4 Rx, 1 CU,
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compared to the “standard” cell used for controlling Approach (50 Nm x 50 Nm) in flat terrains:
• 3 Tx, 3 Rx, 1 CU.
Depending on the situation, Tx#4 could not need to be very powerful.
It would then be interesting to have the possibility to deploy two types of transmitters, one conventional
(e.g. 500W) and a low power (e.g. 50W) which could be used as a Gap-Filler.
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5.3.4 MAIN OPERATIONAL BENEFITS AND FUTURE GROWTH POTENTIAL
The main operational benefits of the envisaged system are synthesised hereafter:
• does not require the target’s cooperation (e.g. for security purpose such as detection of UAVs
and ULAs)
• 3D information,
• fast renewal rate (e.g. 1.5 s),
• robustness (no rotating part),
• redundancy (multiple Tx, multiple Rx),
• possibility to re-use existing infrastructure (e.g. masts, buildings…),
• progressive and adaptive deployment,
• compatible with a “Zero-spare” maintenance concept.
Growth potential are mainly in the area of complementary functions and/or modes such as:
o classification of the type of target (jet, helicopter, propeller driven…), based on the
same approach as further detailed for Wind-Farms,
o Wind-Farm filtering,
• integrated wind profiling.
domain).
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5.4 FEASIBILITY AND RELATIVE COST ANALYSIS
5.4.1 FEASIBILITY ANALYSIS
The feasibility analysis relies on the analysis of each component of the system
5.4.1.1 Tx
The main Tx subsystems are:
• an omnidirectional antenna (e.g. a quarter wave dipole),
• a transmitter (typically 500 W CW),
• a RSG (Radar Signal Generator) able to generate a signal within a 1 MHz bandwidth,
• a Local BIT,
• a COM interface.
A scheme of the transmitter is shown below:
Tx Antenna
(e.g. ¼ Wave)
Coaxial Cable
30m Mast
(GFE)
Transmitter
Box
Ethernet
(GFE)
Power Line
(GFE)
Figure 54: Scheme of a Transmitter
5.4.1.2 Rx
The main Rx subsystems are:
• an omnidirectional antenna (e.g. DBF capable -see Chapter 5.4.1.2.1-),
• RF Units and receivers (see Chapter 5.4.1.2.2),
• Coherent Digital Processing (see Chapter 5.4.1.2.3),
• Non Coherent Digital Processing (CFAR detection, extraction),
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•
•
a Local BIT,
a COM interface.
A scheme of the receiver is shown below:
Rx Antenna
RF Box
Gbit Ethernet
+ Power Line
30m Mast
(GFE)
Processing
Box
Ethernet
(GFE)
Power Line
(GFE)
Figure 55: Scheme of a Receiver
5.4.1.2.1 Antenna
A natural design is a circular antenna, made up of several elements (such as dipoles) and providing
both the required gain and spatial resolution.
Another constraint would be that it must be installed on top of existing masts, thus being lightweight.
This antenna would have the following characteristics:
• Gain > 10 dBi
• Azimuth 3 dB beamwidth < 45°,
A possible design is shown below:
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Figure 56: A possible Rx antenna design
An example of resulting diagrams is shown on Figure 57, for the following conditions:
• Frequency: 435 MHz,
• Focus azimuth: 0°,
Figure 57: A possible Rx antenna diagrams
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5.4.1.2.2 Receiver
With the antenna, the receiver will play a central role in the quality of the signal which will be further
processed and it will have a direct impact onto the system performance for both the detection range
and accuracies.
A conventional radar receiver diagram is shown on the Figure below. The Receiver uses in general a
super-heterodyne structure, with a demodulation on the Local Oscillator (LO) which is determined by
the Transmitter stage (and thus may change in the same way, for instance from burst to burst in the
case of a frequency diversity radar).
LO
~
~
~
~
~
~
RF Unit
ADC
APD
Dig.
Proc
Receiver
Figure 58: Conventional Radar diagram
In the case of a multifrequency radar (in our case, one frequency corresponds to one transmitter),
several architectures can be used:
• Conventional multiple LO receiver (see Figure 59),
• Wideband ADC receiver (see Figure 60),
• Digital Radar receiver (see Figure 61).
LO 1
LO 2
~
~
~
RF Unit
~
~
~
ADC
APD
~
~
~
ADC
APD
~
~
~
ADC
APD
Digital Processing
(N Frequency Channels)
LO N
Receiver
Figure 59: Conventional Multifrequency Radar diagram
In the case of a multistatic radar such as the MSPSR where each frequency corresponds to a given
Tx, this diagram (and the diagrams of the next receiver structures presented on the following figures)
applies to each Rx antenna element (the Digital processing is detailed in Chapter 5.4.1.2.3).
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LO
~
~
~
~
~
~
RF Unit
ADC
ADP
Digital
Frequency
Filter
(e.g. FFT)
Digital Processing
Receiver
Figure 60: Multifrequency WideBand ADC Radar diagram
~
~
~
ADC
APD
Digital
Frequency
Filter
(e.g. FFT)
Digital Processing
RF Unit
Figure 61: Digital Radar
5.4.1.2.3 Processing
Digital Processing would be made up of Coherent Processing (see Chapter 5.4.1.2.3):
• Spatial Filter,
• Range Filter,
• Doppler Filter,
and Non Coherent Processing:
• CFAR Detection,
• Extraction,
• Local Plot filtering.
All I&Q signal are input to the Coherent Processing which, in turn, generates, for each Tx and for each
Rx beam, a Range x Doppler complex image.
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K time samples
On each Range bin:
Range
Filter
(e.g. FFT)
L time samples
L’ Doppler filters
On each Beam:
K’ Range bins
Spatial
Filter
(e.g. DBF)
M’ Spatial Channels (beams)
M Rx Antenna Channels
On each Frequency Channel:
Doppler
Filter
(e.g. FFT)
Figure 62: Generic MSPSR Rx Coherent Processing
5.4.1.3 Central Unit
The main Central Unit subsystems are:
• Data Processing (Fusion, Network management)
• a central BIT,
• COM interfaces.
Functionally, and considering the dataflow/CPU constraints, it is envisaged that each Rx will extract
“plots” (e.g. sections of ellipsoids + Doppler data) for each Tx and transmit these “plots” to the Central
Unit, which will proceed to the intersection of ellipsoids and to the final extraction/filtering.
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5.4.2 RELATIVE COST ANALYSIS
5.4.2.1 Forewords
This cost estimate is done by taking into account some forecast in different technological domains (RF
components, FPGA, PC…) at the horizon where one can expect to develop the MSPSR system
(2010+).
These anticipations were done with the THALES Air Systems best experts knowledge, but as always
for anticipation, there is a part of uncertainty.
As such, this estimate can not be considered as a commitment from THALES Air Systems.
For being tractable, the cost is estimated as a percentage of a classical PSR, but one must keep in
mind that in the complete Cost-Benefit Analysis, other parameters are to be considered such as the
operational use (e.g. is it aimed at replacing a PSR coverage on flat terrain or in mountainous region,
or as a Gap-filler…) and the overall economical balance (e.g. the possibility to detect UAVs in a noncooperative way could avoid to deploy transponder on-board…).
5.4.2.2 Perimeter
The cost perimeter corresponds to the « System acquisition cost » covering the following items :
• Equipments,
• FAT (Factory Acceptance Tests),
• Transport and installation on the site,
• Training and OJT,
• SAT (Site Acceptance Tests).
It does not include:
• Site choice diagnosis,
• Civil works
• Initial logistics (documentation, initial spares, maintenance training),
• Warranty and Annual Maintenance.
The reason why Civil Works and initial logistics are not included is given in Chapter 5.4.2.5.
The technical perimeter corresponds to an Approach/TMA MSPSR configuration containing:
• 3 Transmitters,
• 3 Receivers,
• 1 Central Unit.
5.4.2.3 Hypothesis
The general hypothesis are given below :
• The development is prepared by a demonstration phase starting in 2008,
• The development phase starts in 2010, with a full scale production starting in 2014
• It is supposed that at least 80 MSPSR will be produced during a 10 years period,
7
• An existing infrastructure allows to install the MSPSR on sites ( ).
This planning, given for example only, and covering all the phases is shown below:
7
30m masts, with power line and communication links for both transmitters and receivers
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2007
7 7
Nom activité
8
2008
8 8
8
9
2009
9 9
2010
2011
2012
2013
2014
2015
9 10 10 10 10 11 11 11 11 12 12 12 12 13 13 13 13 14 14 14 14 15 15 15 15
Demonstration
Studies
Performance Objectives vs SESAR
Development & Tests
SAT (Demontrator)
Trial #1
Trial #2
Synthesis
{Concept Validation}
Development & Industrialisation
Engineering
SDR
CDR
Development & Industrialisation
SAT (Qualification Prototype)
{Certification}
Production
Figure 63: Development planning (given for illustration purpose)
More specific assumptions are detailed below:
• Transmitter, containing:
o One Tx Box installed in a waterproof cabinet at the base of a mast
o Coaxial cables between the Tx Box and the antenna
o One Antenna on top of the mast
• Receiver, containing:
o One antenna on top of a mast
o One RF Box installed in a waterproof cabinet beneath the antenna, and connected to
the antenna with coaxial cables
o Gbit Ethernet and electrical cables between the RF Box and the Rx Processing Box
o One Rx Processing Box in a waterproof cabinet at the base of the mast
• Central Unit:
o Doubled machine for redundancy reasons,
o Enclosed in a waterproof cabinet
5.4.2.4 Synthesis
8
The cost is given in percentage of the current (2007) cost of a classical PSR ( ), estimated with the
same perimeter as described above (see 5.4.2.2).
Depending on the hypothesis on the various technology anticipations, this relative cost is estimated to
be between 55% and 65%.
It is also noticeable (see 5.4.2.5.2) that the MSPSR design allows to reduce the overall Life Cycle Cost
9
thanks to an advanced maintenance concept ( ).
8
9
Assuming that the cost of classical PSR will stay approximately constant in the coming years
This maintenance concept including a “hot maintenance” capacity.
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5.4.2.5 Complementary analysis
5.4.2.5.1 Civil Works
Civil Works are voluntarily excluded in this estimate, because they are expected to be very site
10
dependent, and thus difficult to compare with a conventional PSR ( ).
5.4.2.5.2 Maintenance Concept
The loss of one Transmitter or Receiver does not affect the Operational Service which is to provide plot
data to the ATC Centre.
Taking into account the current reliability data, the estimated number of expected failure for one
MSPSR cell (50 Nm x 50Nm) is evaluated to less than one per year.
For such a kind of system, an efficient, modern and cost effective logistic support could be proposed
during all the system life cycle, such as illustrated below:
Figure 64: “Zero-Spare” Maintenance concept
One very interesting advantage from the classic Primary Approach radar is that the traditional logistic
support could be reduced for the MSPSR system, and the logistics and maintenance costs drastically
decreased.
In fact, the initial logistic support could be reduced at the minimum:
• No human maintenance resources,
10
For a PSR, Civil Works means in general a tower with all the necessary electrical (e.g. 30 kVA) and
communications links
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•
•
•
•
•
•
No maintenance facilities (storage, workshop,…),
No specific maintenance documentation,
No specific maintenance or Operational training,
No specific maintenance Tools & Test Equipment,
No Consumables,
Possibility to centralize the LRU spare in industrial facilities for all customers common use.
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5.5 RECOMMENDATIONS
5.5.1 RECOMMENDATIONS FOR FUTURE APPLICATIONS
Some initial actions have already been undertaken (see Ref. [2.5] and [4.18]), and must be pursued in
the perspective of WRC 2007, 2010 and 2013.
The deployment of MSPSR will be facilitated by the use of a detailed “sitting tool” allowing to optimize
the Tx and Rx locations.
The deployment of MSPSR in mountainous region will be optimised if two types of Transmitters are
available:
• a standard 500W transmitter for normal applications,
• a gap-filler 50W transmitter for specific use (e.g. in valleys).
5.5.2 RECOMMENDATIONS FOR FUTURE STUDIES
The works conducted in the frame of this study give a strong feeling that an alternative detection
technique to supplement PSR coverage is feasible.
It would then be useful to anticipate a follow-on study dedicated to the solving of main issues (e.g. EM
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6. CONCLUSIONS
The activities conducted in the frame of this study are very encouraging and give a strong feeling on
the feasibility of a Multi-Static PSR system to Supplement PSR Coverage.
It is based on a sparse network of omnidirectional UHF transmitters (Tx) and omnidirectional receivers
(Rx) interconnected to a Central Unit. It establishes a 3D non-dependant air situation including noncooperative targets (such as UAVs and ULAs). The configuration is adaptable to the environment and
reconfigurable. It could re-use existing infrastructures such as communication masts.
Assessments show that its performance comply with the requirements for Approach/TMA even on low
RCS targets (e.g. UAVs).
The coverage can be extended by adding Tx and Rx as necessary, in order to correspond to various
applications such as Approach or En-route, and also in difficult regions such as mountains.
It offers several improvements compared to a conventional PSR:
• 3D detection in position and velocity,
• higher renewal rate (e.g. 1.5 s instead of 4-5 s),
• resistance to Man-Made Noise and Wind-farms effects.
The MSPSR acquisition cost is estimated between 55% and 65% of a classical (2D) PSR. In addition,
its fail-soft design is compatible with a “Zero-spare” maintenance concept, which also reduces the total
Life Cycle Cost.
The envisaged system also offers many growth potentials in certainly valuable domains such as:
o classification of the type of target (jet, helicopter, propeller driven…)
o Wind-Farm effects filtering,
• integrated wind profiling,
domain).
Some initial actions have already been undertaken and must be pursued in the perspective of WRC
2007, 2010 and 2013.
It is recommended to conduct a follow-on study dedicated to the solving of main issues (e.g. EM
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