Evaluation Results ofAirport Surface Multilateration
Hiromi MiyazakiElectronic Navigation Research Institute1Contents
Introduction
Background, Purposes

Overview of Multilateration (MLAT)
Advantages, How to get high performance
Evaluation Tests
Method, Evaluation system, Results

Conclusion

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Contents
Introduction
Background, Purposes

Overview of Multilateration (MLAT)
Advantages, How to get high performance
Evaluation Tests
Method, Evaluation system, Results

Conclusion3

What is the Multilateration?
Multilateration is a new surveillance system which
detects signals of aircraft transponders and measures
the aircraft positions by TDOA technique.
Receiver A

Receiver C

Receiver B
TDOA: Time Difference of Arrival4

Back Ground(Why do we introduce MLAT)

Increasing aviation demands have brought expansionsof major airports
Layouts and operations in the airports have become
more complex
To ensure safe and smooth operation in this situation,an essential requirement is to provide accurate andhighly reliable surveillance information to controllers

Need to Introduce MLAT!!
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Purposes of Evaluation(Why do we evaluate MLAT)ENRI has conducted evaluation tests of MLAT
by using an evaluation system at major airports.
Main purposes are;To verify performance at each airport

To propose optimal receiver antenna layout
based on the test results

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In This Presentation
Evaluation results at Kansai international air port (A/P)
Kansai A/P has specific restrictions for antenna layout
Surrounded on all four sides by sea
Not install antennas on the top of the terminal building
To overcome above restrictions
Provide our lessons learned from evaluations
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Contents
Introduction
Background, Purposes

Overview of Multilateration
Advantages, How to get high performance
Evaluation Tests
Method, Evaluation system, Results

Conclusion

8View from ATC tower

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Conventional Surface Surveillance System(SMR: Surface Movement Radar)

SMR has some problems such as;
No identification information on the controller screen
Performance degradation in the bad weather condition
Blind area blocked by large airport buildings
Blind

SMR Display

10Advantages of MLAT
Call sign display on a controller screen
Good Performance in all weather conditions
No blind area by adapting the antenna layout
No additional avionics equipment to aircraft

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Principle of Positioningab

Hyperbolic lines: a – b = “Constant”

12Principle of Positioning
Hyperbolic lines calculated by TDOA
between Receiver A and Receiver B

Receiver A

Receiver B
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Principle of Positioning
Hyperbolic lines calculated by TDOA
between Receiver B and Receiver C

Receiver C

Receiver B
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Principle of Positioning
The aircraft position is fixed as
Intersection of two hyperbolic lines

Receiver A

Receiver C

Receiver B
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How to Get High Performance
Positional relationship between aircraft and receivers

Good relation

bad relation

Small error

Large error
16How to Get High Performance
To avoid signal interference by reflection of buildings
No detection
Not positioning

Direct signal

Difficult to decode

Multipath signal
17Contents
Introduction
Background, Purposes

Overview of Multilateration
Advantages, How to get high performance
Evaluation Tests
Method, Evaluation system, Results

Conclusion

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Evaluation Method
Evaluation items: Detection rate, Position Accuracy
European standard: Performance requirement
Detection Rate

Runway/Taxiway
Gate (Spot)

More than 99.9% (2s)More than 99.9% (5s)

Position AccuracyLess than 7.5m
Less than 20m

Evaluation by a Test vehicle equipped with a transponder
To collect data efficiently to large evaluation areas

Transponder Antenna

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Evaluation System50cm1mAntenna

Receiver unit
Target processor

20Antenna Layout(Our Concept)

Our experiences from past evaluations
Performance degradation: Signal interference
Big problem: Huge installation cost
Large number of RUs: Bring overload of the processor

To avoid above problems
To locate antennas as high as possible
To install antennas in existing facilities
as much as possible
To keep the number of RUs as low as possible
21Antenna Layout(Restricted Conditions)

Surrounded on all four sides by sea
Difficult to install antennas widely around the airport
Antenna height is restricted by transition surface
Strong restriction for MLAT to get high performanceat runway/taxiway area

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Antenna Layout(Restricted Conditions)

Sophisticated terminal building in Kansa A/PTo install antennas on the top of the terminal building
is restricted due to a standpoint of the design
Strong restriction for MLAT to get high performance
at apron area23

Layout of RU antennas

ATC tower

A/G tower

ILS Middle
GlideRoofSlopeof cargo buildingILSMarker24

Layout of RU antennas

2 RUs were installed on top of ATC tower
ATC tower

Installation cost is cheaper than Haneda, Narita
Number of RUs: 18 units is smaller than Haneda, Narita
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Test Results(Runway/Taxiway Area)
B runway area
J3 taxiway area

Accuracy:6.5m
Detectin:100%

Accuracy:6.8m
Detectin:100%

Accuracy:6.3m
Detectin:100%

A runway area

Requirements

Detection: 99.9%

Accuracy: 7.5m
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Test Results(Apron Area)

Accuracy: 11m
Detection: 100%

Accuracy: 57m
Detection: 41%

Accuracy: 15mDetection: 100%

Accuracy: 13m
Detection: 100%

Accuracy: 17m
Detection: 100%

Accuracy: 9.6m
Detection: 100%

Requirements

Detection: 99.9%

Accuracy: 20m
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Test Results(Apron Area)

Accuracy: 11m
Detection: 100%

Accuracy:57m
Accuracy: 57m
Detection:
41%
Detection: 41%

Surrounded all four side bybuilding

Accuracy: 15m
Detection: 100%

Accuracy: 13m
Detection: 100%

Accuracy: 17m
Detection: 100%

Accuracy: 9.6m
Detection: 100%

Requirements

Detection: 99.9%

Accuracy: 20m

Most difficult area28

Most Difficult Area29

Lessons learned from the Evaluation
An apron area where is surrounded on all four sides bybuilding is most difficult area to get good performance

To improve performance in such area, it is consideredthat some advanced techniques are required for signal
detection and processing

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Conclusion
MLAT is a new surface surveillance system
to be able to improve functions and performance

Performance values satisfied requirements to almost area
Restrictions to install antennas exist in airports

Our lessons learned from the evaluation are effective
The operation at Kansai A/P will start next year31Thank you for your attention!!

Any questions?

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