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Forum for Electromagnetic Research Methods and Application Technologies (FERMAT)

Effects of Pulsed RF Disturbances on Aeronautical

Communication SystemsEmmanuel Van Lil1, Jo Verhaevert2, Jan De Vos & Dirk Van Troyen3

• 1 Div. ESAT-TELEMIC, KU Leuven, B-3001 Heverlee, Belgium, Emmanuel.VanLil@ESAT.KULeuven.Be

• 2 Dept. Industrial Technology & Construction, UGent, B-9000 Gent, Belgium, Jo.Verhaevert@UGent.Be

• 3 Technologiecluster Elektrotechniek, KU Leuven, B-2860 Sint-Katelijne-Waver, Belgium, Dirk.VanTroyen@KULeuven.Be

Abstract: Air Traffic Control (ATC) and their responsible authorities have been always very sensitive to safety of the systems they are using

to guarantee a fool-proof and environmentally safe operation of the facilities to provide guidance for the airplanes. Not only the most

elaborated systems up to RADAR might be influenced by f.i. wind turbines, but even the old standard air-ground aviation communication

systems are prone to interference by other (undesired) signals. This paper deals with the influence of pulsed systems on aviation

communication systems. After simple simulations, measurement campaigns, both in an accredited lab and in the field, and with different

kinds of sources, from continuous over well defined pulsed to random pulsed are described. An qualitative analysis of the inaccuracies of

those measurements is performed and the influence of (shielded and unshielded) spark plug systems on specific aviation communication

systems (still based on Amplitude Modulation (AM)) is explained in detail. To conclude, possible remedies (like a shield or the sensitivity

reduction of the recievers) are proposed.

Keywords: Pulsed RF, EMC, aeronautical communication, spark plug interference.

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References:

• IEC, "CISPR 22: Information technology equipment - Radio disturbance characteristics - Limits and methods

of measurement", 11/1997.

• Iris De Coster, E. Van Lil, Thomas Neubauer and T. Ergoth, “Comparison of indoor penetration

measurements with geometric and Physical Optics Predictions”, Proc. Millennium Conference on Antennas

and Propagation, Davos, Switzerland, 4 p., 9-14 April 2000

• J. MacAlpine en W. Yim, “Computer Modelling of Trichel Pulses in Air”, Conference on Electrical

Insulation and Dielectric Phenomena, Virginia Beach, USA, 22-25 October 1995

• ITU-R Recommendation P526-4, , ITU, Place des Nations, 1211, Geneva 20, Switserland

*This use of this work is restricted solely for academic purposes. The author of this work owns the copyright and no reproduction in any form is permitted

without written permission by the author.*

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Effects of Pulsed RF Disturbances on Aeronautical Communication Systems

• Prof. dr. ir. Emmanuel Van Lil, dr. ir. Jo Verhaevert, ing.

Jan De Vos & Prof. dr. ir. Dirk Van Troyen

• KU Leuven, div. ESAT/TELEMIC

• Kasteelpark Arenberg, 10; Bus 2444

• B-3001 Leuven-Heverlee; Belgium

• Web : http://www.esat.kuleuven.be/telemic(/propagation)

• E-mail: Emmanuel.VanLil@ESAT.KULeuven.Be

• Poster for EUCAP 2015

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Outline

• Introduction

• Theoretical computations

– Would require 495 m for class A

– Actual road was 275 m and no problems were noticed

• Experimental verifications

– Sparks in continuous operation (ignition of central heating

– Sparks in a car

– Measurements of pulses on site

– CW interference

– Effects on communication systems

• Conclusions

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Standards

• Literature essentially EMC/EMI standards• [IEC] IEC, "CISPR 22: Information technology equipment - Radio disturbance

characteristics - Limits and methods of measurement", 11/1997 (Class A 57 dBV/m

>250 MHz & 50 dBV/m between 30 & 250 MHz @3 m; Class B= 10 dB lower)

• [IEC2] IEC, "CISPR 11: Limits and methods of measurement of radio disturbance

characteristics of industrial, scientific and medical (ISM) radio-frequency equipment",

11/1997

• 72/245/EEC directive till January, 1, 1996

• After January, 1, 1996: “Automotive EMC directive 95/54/EC”

• Definition of a pulse: < 30 sec

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Theoretical computations

• Receiving antennas on 20 m high platforms

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Theoretical computations

• For vertical polarisation: CW class A equipment would

require 495 m

• Nothing was experienced, even if the way was at 275 m

• Now road at 65 m

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Theoretical computations

• Antennas: mostly dipoles (one array of 4) for the civilian

band (118-137 MHz) and cone antennas for military

communications (225-400 MHz)

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Measurements: continuous sparks

• In Open Area Test Site

Ignitition System of a

Central Heating System

kul

vonk

EUT: 1v

File name: vonkv.RES

17. Apr 01 09:47

PAGE 1

Scan Settings (2 Ranges)

|--------- Frequencies -----------||--------- Receiver Settings ---------|

Start Stop Step IF BW Detector M-Time Atten Preamp

30M 300M 50k 120k PK 1ms 10dBLD ON

300M 1000M 50k 120k PK 1ms AUTO LN ON

Transducer No. Start Stop Name

21 30M 1000M BILMV

-20

0

20

40

60

80

dBuV/m

90

30

MHz

1000100

RADEM_B

Mkr : 119.1000 MHz 55.5 dBuV/m

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In Situ Measurements

• Spark Plug Setup

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In Situ Measurements

• Detail of Spark Plug Setup: effects till 120 m (heavy

effects below75 m)

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Analysis of the pulses

• Detail on Spectrum Analyser

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Analysis of the pulses

• Voltage over ignition coil (detail)

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Analysis of the pulses

• Broadband Antenna Voltage (detail)

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Measurement of CW pulses

• Calibrated pulse transmission system

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Measurement of CW pulses

• Problems: heavy depolarisation, due to fences

• Therefor, direct connection transmitter/receiver was testedOpening of the receiver in function of the pulse duration (PRF=500 Hz=15000 t/min 4takt)

0

20

40

60

80

100

120

-85 -80 -75 -70 -65 -60 -55 -50

Signal level in dBm

Du

rati

on

of

the in

terf

ere

nce in

mic

roseco

nd

s

RX882C On msec

RX882C Off msec

RX908T On msec

RX908T Off msec

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Shielding possible

• Shielding is possible (mesh of 1.66 m attenuates 9 dB)

-30

-25

-20

-15

-10

-5

0

5

10

15

20

0 20 40 60 80 100 120

Req

uir

ed

att

en

uati

on

in

dB

Distance in m

Extra attenuation in function of the distance to the interferer

Distance

Pattern

Total

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Acknowledgements

• Belgocontrol (= Belgian FAA, ir. Jan Cottyn, ir. Manu

Deklerck, ir. Alain Bruggeman, ir. Luc Lauvrijs)

• B(elgian)I(institute) for P(ost and) T(elecommunications)

(=Belgian Telecom Authority; ir. Freddy Baert)

• Military ATC (Lt. Col. ir. Albert Husniaux, also NATO

RTO co-ordinator)

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Conclusions

• One should use a large amount of caution when dealing

with pulsed signals, both for measurements and

calculations

• For safety also the maximal energy in a pulse is important

• Product of duty cycle times fields is important for reliable

air-ground communications

• Spark plugs can generate disturbances in a wide

frequency band

• Solutions: shielding or reducing sensibility (from 1 to 2

V) or 6 dB.