Wide Area Multilateration Demonstration System

Rudolf Seller, Ádám Szüllő

Budapest University of Technology and Economics

Radar Research Group

WAMLAT

• Passive distributed radar system to improve ATC reliability

• Wide-area coverage (>10km diameter)• Multiple receivers• Synchronization challenge• GPS based synchronization

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WAMLAT System

• GPS based synchronization• Data transfer via Ethernet• Server

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Geometry of the Receivers

• Multilateration is nonlinear• Location dependent position

estimation accuracy• Zone defined

by the receivers

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Synchronization

• GPS Disciplined Oscillator (GPSDO)• No physical clock distribution network• Tens of nanosecond accuracy

• Long term time difference measurement between two GPSDOs:

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Arrangement of the Receivers

• Across and around the city of Budapest• Not optimal geometry

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Results

• Persistent displaying• Fligth information from http://www.flightradar24.com

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Results

• Mode A and Mode C based multilateration has high false detection rate

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Results

• Only Mode S based multilateration

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Results

• „Invisible” aircraft

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Location dependent accuracy

• Multilateration is nonlinear

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Accuracy of the system

• Multilateration compared to ADS-B• ADS-B accuracy is questionable

(eg. systematic error because of delay)• Accuracy estimation based

on longterm dataset• Median error is 128 meters• Estimated accuracy is

150 meters

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Future work

• Develope tracking algorithm

• Expand the system nation-wide

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Thank You!

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