Novel EMC analysis to ensure

safety in railway infrastructuresMarc Pous Solà

marc.pous@upc.edu

Content

� Standard EMC measurements

� Highlight railway application limitations

� Unable to predict distortion of digital communication systems

� Novel Time Domain measurement methodology

� Developed TDEMI

� Protect communication systems

� Summary

2

Standard EMC measurements

� EMC Goal: ensure disturbance generated does not interfere with telecommunications and other equipment

� DCS related to Railway safety

� Standard emissions test

� Without movement (QP detector)

� With movement (PK detector - time limitations)

� Measure only some µs at each frequency

� Miss many possible disturbances

� Characterize full-spectrum properly

� Impossible due to measurement receiver architecture

3

� Frequency sweep method (EMI receiver)

� Measurement of time-varying sources is known to be a problem with the frequency domain method

Problems of standard EMC measurements

� In-situ EMC emissions measurements limitations

� Sources of uncertainty

� Don’t know source interference (Railway or elsewhere) special for urban scenarios

� Not possible to use conventional methods due to long measurement time

� frequency domain approach measures each frequency at a different time

� Evaluate all functional modes

� Regenerative breaking

� Railway and transient interferences

� Arching, switching

� occurs randomly

� Cause interferences with Eurobalise or GSM-R

4

Problems of standard EMC measurements

� Radiated transient interferences are broadband impulsive noise

� Frequency sweep measurement or not-full spectrum time domain are not useful

� The level, frequency, duration and interval of the transient interference must be considered

� Eurobalise � 27 MHz, …

� DVB-T � 510 – 690 MHz

� GSM-R � 890 – 960 MHz

0 0.2 0.4 0.6 0.8 1 1.2

x 10-6

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

Time

Am

plit

ud

e (

V)

0 2 4 6 8 10

x 108

2

4

6

8

10

12

x 10-7

Frequency (Hz)

Tim

e

-150

-140

-130

-120

-110

-100

dBVTime-domain transient measurement

5

Problems of standard EMC measurements

� Standard EMC evaluation

6

� Defined for analogue systems

� Frequency sweep measurements

� QP detector related with human

perception on analogue

communication systems

� Signal-to-Noise-Ratio (SNR) is the

main figure of merit

� Fixed measuring BW (120 kHz

from 30 MHz to 1 GHz)

30 40 60 80 100 200 400 600 1000

0

10

20

30

40

50

60

dB

µV

/mMHz

0 2 4 6 8 10

x 108

2

4

6

8

10

12

x 10-7

Frequency (Hz)

Tim

e

-150

-140

-130

-120

-110

-100

� Confuse broadband impulse noise with narrow

band interference

� Only capture repetitive interferences when the

sweep is synchronized with the interference

Standard EMC meas: Protect communication systems

� Standard measurement and evaluation

� Cannot relate measurement with interference produced (PK, QP, BW,…)

� Underestimate interference � Not properly captured (transient)

� Overestimate interference � Captured (pessimistic worst-case)

� New meas & evaluation to protect communication systems needed

� Evaluate real effects on digital communication systems

� Protect GSM-R, Eurobalise, digital broadcasting,… from unwanted railway emissions

7

Movement PK

measurement

• Interference

Probability

distribution

• APD � Bit-Error-

Probability (BEP)

-110 -105 -100 -95 -90 -85 -80 -75 -70 -65 -6010

-7

10-6

10-5

10-4

10-3

10-2

10-1

100

Power (dBm)

Pro

ba

bili

ty

RxQUAL1

RxQUAL2

RxQUAL3

RxQUAL4

RxQUAL5

RxQUAL6

RxQUAL7

SLR interference

SHR interference

No interference

30 40 60 80 100 200

0

10

20

30

40

50

60

dB

µV

/m

MHz

• Limit line

• SNR

• Analogue sys.

Novel Time Domain EMI measurement

� Developed TDEMI

� Transient interference measurements

� Multiple instantaneous measurements

� Interference decomposition

� Protect Digital communication systems

� Employing time-domain captures

� IQ and APD

8

≡

Developed Time-Domain EMI

� Based on: Scope capture + Post-

processing

� Excellent results compared with

EMI receiver (8 bits OSC)

� Accuracy and dynamic range

� Obtain Full spectrum with a

single measurement

� Ideal for unique event interferences

� Evaluate all different EUT modes

100 1000-10

0

10

20

30

40

50

60

70

80

Frequency (MHz)E

(dBµ

V/m

)

EMI Test receiver

TDEMI system

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07-0.1

-0.05

0

0.05

0.1

0.15

Time (µs)

Voltage (

V)

9

Developed Time-Domain EMI

� Compact TDEMI system

� Laptop + Scope

� Measurement time decreased.

� PK and AVG < 30 s from 150 kHz to 30 MHz

� The spectral estimation single time-domain acquisition

� The entire EMI frequency spectrum correspond to the same time frame

� Simultaneous measurements (4 channels)

� Conducted, radiated, …

� Low cost and portable (battery) 1 10 3010

20

30

40

50

60

701 µs Rectangular pulse @ 1 kHz

Voltage (

dBµ

V)

Frequency (MHz)1 10 30

10

20

30

40

50

60

70

80

901 µs Rectangular pulse @ 100 kHz

Voltage (

dBµ

V)

Frequency (MHz)

GCEM TDEMI

EMI Receiver

GCEM TDEMI

EMI Receiver

10

Developed TDEMI for transient interferences

0 1 2 3 4 5

x 10-3

-1000

-500

0

500

1000

Time (s)

Voltage(m

V)

Channel A

� Transient interference measurements

� Acquisitions are triggered by a certain

event or by an external signal.

� Capture transients is possible and easy

� Perfect for in-situ EMI assessments

� Evaluate all functional modes

� Synchronize measurement

11

Developed TDEMI: multiple instantaneous measurements

� Several input channels

� Multiple measurements at the same time

� NF triggering – FF capture

� EMI measurements are instantaneous

� Synchronize measurement with transient

� Up to 4 channels for simultaneous

measurements

Voltage

(m

V)

Voltage (

mV

)

FF capture NF capture

12

Frequency (MHz)

100 230

TDEMI+NF Trigger

Developed TDEMI: multiple instantaneous measurements

� Same instant multiple captures

� Conducted emissions

� Measure all lines at the same time

� Real common-mode and differential-

mode disturbance measurement

� Simultaneous Electric and Magnetic

field probe (TD operation is needed)

13

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

0

0.05

0.1

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

0

0.05

0.1

0.155 0.16 0.165 0.17 0.175 0.18 0.185

0

0.05

0.1

0.155 0.16 0.165 0.17 0.175 0.18 0.185 0.19

0

0.05

0.1

Developed TDEMI: interference decomposition

� Background noise cancellation

� Decomposition of interferences

� Identify transient and CW interference

� Ideal for in-situ measurements

30 100 100025

30

35

40

45

50

55

60

65

70

75

Frequency (MHz)

E-f

ield

(d

Bµ

V/m

)

ESPI

TDEMI

FM broadcasting

GSM jamming signal

Transient EMI

14

Developed TDEMI: interference decomposition

0 0.2 0.4 0.6 0.8 1

-20

0

20

Time (ms)

IMF

1 V

olt

ag

e (

mV

)

Transient Mode

30 100 100020

30

40

50

Frequency (MHz)

IMF

1 E

-fie

ld (

dBµ

V/m

)

0 0.2 0.4 0.6 0.8 1-4

-2

0

2

4

GSM jamming signal

Time (ms)

IMF

2 V

olt

ag

e (

mV

)

0 0.2 0.4 0.6 0.8 1-4

-2

0

2

4

Time (ms)

FM broadcasting

IMF

3 V

olt

ag

e (

mV

)

30 100 1000

20

30

40

50

60

Frequency (MHz)

IMF

3 E

-fie

ld (

dBµ

V/m

)

30 100 1000

30

40

50

60

70

Frequency (MHz)

IMF

2 E

-fie

ld (

dBµ

V/m

)

30 100 100020

25

30

35

40

45

50

55

Frequency (MHz)

E-f

ield

(dBµ

V/m

)

ESPI

IMF1

15

� Capability to isolated different interferences

� Employing Time Domain data

� Impulsive noise

� Transient interference

� GSM jamming

� FM broadcasting

Protect Digital Communication systems

� EMC standards are not useful to

predict interference

� Limit line related with SNR

� Pk and QP measurement

� 120 kHz BW non-sense (developed for

analogue systems)

16

0 200 400 600 800 1000 1200 1400 1600 1800 2000-30

-20

-10

0

10

20

30

Samples

Am

plit

ud

e (

µV

)

30 40 60 80 100 200 400 600 1000

0

10

20

30

40

50

60

dB

µV

/m

MHz

� Employ captured Time Domain data

� Obtain in-phase and quadrature components IQ

at the frequency band of the communication

system

� Obtain the amplitude probability distribution

(APD) at any desired frequency band

� Allow us to fulfil the requirements defined in the

directive

TDEMI: Protect Digital Communication systems

� GSM-R system interfered by radiated transients

� With standard methodology difficult (near to impossible) to capture

properly transient interference

� It is not feasible to relate Pk or QP meas with the error produced to

GSM-R system

� Time domain data � IQ capture and simulation

� IQ obtained at the frequency band of the DCS

� Simulate GSM-R sys. to obtain BER in presence of transient

17

0 200 400 600 800 1000 1200 1400 1600 1800 2000-30

-20

-10

0

10

20

30

Samples

Am

plit

ud

e (

µV

)

IF Data

IQ Data Possible to obtain BER

TDEMI: Protect Digital Communication systems

� Results employing APD diagram including GSM specification limits

� Easy to identify the worst case of interference

� Predict RXQUAL level and BER from APD diagram

18

-110 -105 -100 -95 -90 -85 -80 -75 -70 -65 -6010

-7

10-6

10-5

10-4

10-3

10-2

10-1

100

Power (dBm)

Pro

ba

bili

ty

RxQUAL1

RxQUAL2

RxQUAL3

RxQUAL4

RxQUAL5

RxQUAL6

RxQUAL7

SLR interference

SHR interference

No interference

Interference

APD diagram error

estimation

BER RXQUAL

SHR(High Rate) 1.8 % RXQUAL_4

SLR (Low Rate) 0.09 % RXQUAL_0

RXLevel

������ , ������ ≡��

, ����

� APD - BER limits:

� Probability error requirements

� Amplitude received (RXLevel)

� Modulation scheme

TDEMI: Protect Digital Communication systems

� Results obtained

� We can predict the degradation suffered by GSM with previous TD measurements

� Excellent results achieved

� Negligible interference for SLR

� RXQUAL_4 result for SHR

� APD really useful � fast capacity interpret results and quantify degradation

19

Interference

Measured Signal quality

by GSM MS Test unit

DCS simulation

methodology

APD error

estimation

RXQUAL BER RXQUAL BER RXQUAL BER

SHR (High Rate) RXQUAL_4 2.07 % RXQUAL_4 2.39 % RXQUAL_4 1.8 %

SLR (Low Rate) RXQUAL_0 0.01 % RXQUAL_0 0.04 % RXQUAL_0 0.09 %

-110 -105 -100 -95 -90 -85 -80 -75 -70 -65 -6010

-7

10-6

10-5

10-4

10-3

10-2

10-1

100

Power (dBm)

Pro

ba

bili

ty

RxQUAL1

RxQUAL2

RxQUAL3

RxQUAL4

RxQUAL5

RxQUAL6

RxQUAL7

SLR interference

SHR interference

No interference

Summary

� Standard EMC measurements are not effective

� Only frequency domain data available, QP (120 kHz) or PK

� Miss many information specially from transients

� Impossible to relate with BER

� Developed time domain methodologies

� Instantaneous acquisition

� Multiple channels

� Ideal for transient interferences (triggering)

� Decomposition of interference: cancel background noise � ideal for in-situ

� Predict the degradation of communication systems including transient

interference

� IQ components

� APD (Amplitude Probability Distribution)

20

BcnRail INNOVA

Proyectos estratégicos ferroviarios de I+D+i

Novel EMC analysis to ensure safety in railway infrastructures

Marc Pousmarc.pous@upc.edu

GCEM-UPC

Nº Expediente: PTR-2014-0351

21

Novel EMC analysis to ensure

safety in railway infrastructuresMarc Pous Solà

marc.pous@upc.edu