Electromagnetic Emission of an Optical-to-BroadR-Reach Converter

Dennis Degueldre, Thomas Waas and Markus Kucera

Computer Science and Mathematics, OTH-Regensburg, Prfeninger Strasse, Regensburg, Germany

Keywords:

BroadR-Reach, EMC, Media Converter.

Abstract:

The automotive solution for Ethernet is BroadR-Reach, which cannot be found as a common Ethernet-interface

in the consumer industry. Hence a media converter from IEEE 802.3 Ethernet to BroadR-Reach is needed to

debug and test the communication of automotive devices under test (DUT). If the functionality of a BroadR-

Reach connection has to be tested for electromagnetic compatibility (EMC), a BroadR-Reach to optical media

converter is needed, which has to comply to the same EMC test speciﬁcations as the DUT. This research

explains the internal structure of a media converter and deﬁnes a test setup for copper bound emission test of

BroadR-Reach. By using a standardized stripline measurement like it is common for electromagnetic emission

test, it could be shown, that the tested Technica/Tinytron media converter can safely be used inside an EMC

chamber.

1 INTRODUCTION

Current automotive bus systems are not able to ful-

ﬁl bandwidth demands of future automotive applica-

tions. A promising alternative solution is the use of

switched Ethernet in a vehicle. Ethernet provides high

data rates and it is possible to create different topolo-

gies within a switched Ethernet network. One solu-

tion is the BroadR-Reach technology which enables

a data rate of 100 Mbit/s over unshielded twisted pair

cables. This adapted physical layer for automotive

use makes Ethernet more cost-effective to reduced

wiring effort, reduced shielding effort, and reduced

connector cost (Bruckmeier, 2010).

The OPEN (One Pair Ethernet Network) Alliance

(OPEN Alliance, 3 05) is enabling a wide scale adop-

tion of Ethernet-based automotive connectivity. The

main goal is to establish industry standards for Eth-

ernet connectivity over an unshielded single twisted

pair cable. This alliance was founded in November

2011 and is supported by the vehicle industry, suppli-

ers and chip manufacturers. The OPEN Alliance is a

central point where open questions with Ethernet for

in-vehicle use are discussed and solutions are devel-

oped.

One of the open questions is how to qualify the DUTs

inside of an electromagnetic test chamber. This is an

electromagnetic shielded chamber where the emission

and the immunity of Electronic Control Units (ECU)

can be tested under realistic conditions. Therefore all

the network and control lines are connected to a coun-

terpart inside or outside of the chamber to communi-

cate with an residual bus simulation or control real

actors. Since an copper based connection in or out

of the chamber would inﬂuence the EMC measure-

ments, all connections to the outside of the chamber

have to be optical. This avoids distortion of the mea-

sured data while having an eye on electromagnetic

emission. This is the ﬁeld of application for optical

Ethernet-to-BroadR-Reach media converters.

2 GOAL OF THIS PAPER

This paper gives a look in the inside of an BroadR-

Reach media converter and explains how a conversion

between optical Ethernet and BroadR-Reach is done

to understand which stages in the conversion can in-

ﬂuence the quality of the signal. To guarantee that the

media converter itself does not add any distortions to

the whole system under test, it is measured separately

under the same conditions and requirements to qual-

ify its electromagnetic compatibility. The goal is to

verify, that the EMC limits - in this paper the limits

from BMW Group Standard 95002(BMW Group, 4

10) - are not exceeded.

131

Degueldre D., Waas T. and Kucera M..

Electromagnetic Emission of an Optical-to-BroadR-Reach Converter.

DOI: 10.5220/0004711401310135

In Proceedings of the 4th International Conference on Pervasive and Embedded Computing and Communication Systems (PECCS-2014), pages

131-135

ISBN: 978-989-758-000-0

 2014 SCITEPRESS (Science and Technology Publications, Lda.)

3 RELATED WORK

Broadcom is the inventor and the ﬁrst chip manu-

facturer of BroadR-Reach with unshielded 2-wire ca-

bling technology (Broadcom, 3 05). There are no

public investigations available about the electromag-

netic compatibility of their technology. Several EMI

(Electromagnetic Interference) and EMC (Electro-

magnetic Compatibility) measurements were done by

the automotive OEMs and ﬁrst tier suppliers with the

two wire Ethernet approach under automotive condi-

tions (Verdon and Tazebay, 3 09) (Strobl, 0 25). The

results have shown that the technology has proven its

capabilities for data communication in vehicles. The

BroadR-Reach standard is completed by the OPEN

Alliance, where several compliance and test speciﬁ-

cations are deﬁned. The goal of those tests is the rat-

iﬁcation of the standard but not of the built up prod-

ucts. The signal quality of the products is inﬂuenced

by the layout, the used ﬁlter topologies, shielding and

the connectors used. Therefore tests have to be made

for each new product. Especially in case of a media

converter for in EMC test chamber use the neutrality

has to be ensured to avoid distortion while measuring.

With focus on the two port converters there are

three commercial media converters on the market.

One is an 100BASE-TX to BroadR-Reach ”Back-

to-Back” media converter from Continental Automo-

tive GmbH. This converter was the ﬁrst on the mar-

ket and was developed for internal laboratory- and

demonstrator use. It is available at Continental Engi-

neering Services (Continental Engineering Services,

3 07). An enhanced, electromagnetic compatible ver-

sion is currently in development. The second and

the third are media converters from Technica Engi-

neering/tinytron. A 100BASE-TX and one optical

Ethernet-to-BroadR-Reach converter (Technica Engi-

neering, 3 07). Especially the optical version was

designed to be used in an EMC test chamber and is

evaluated within this research. This makes this de-

vice the only commercial media converter which was

designed for in EMC chamber use.

4 FUNDAMENTALS

4.1 BroadR-Reach

BroadR-Reach is an IEEE 802.3 Ethernet based tech-

nology which allows to send data with a data rate

of 100 Mbit/s over an unshielded twisted pair of ca-

bles. It was invented to provide a high data rate con-

nection for existing old ofﬁce buildings which are

not equipped with Cat.5e cables, but rather two wire

phone cables.

BroadR-Reach deﬁnes a physical layer which uses a

different coding scheme than IEEE 802.3. So in dif-

ference to 100BASE-TX which uses two pairs of ca-

bles, BroadR-Reach uses only one. On top of that it

was optimized to fulﬁl automotive EMC and EMI re-

quirements. Therefore, it uses a three stage pulse am-

plitude modulation (PAM-3) with a fundamental fre-

quency of 33.3 MHz. This technology is available as

a single physical layer transceiver (PHY) or as bridg-

ing IC with several integrated standard and BroadR-

Reach interfaces. As typical for an Ethernet PHY it

supports the standard interfaces to the MAC (Media

Access Control) Layer via Media Independent Inter-

face (MII), Gigabit MII (GMII) or Serial GMII (SG-

MII) which can be directly connected to a small form-

factor pluggable (SFP) interface.

4.2 Small Form-factor Pluggable

Interface

The description SFP is used for a hot-pluggable and

swappable device that contains a transceiver as well

as the interface connector. A SFP module consists of

a PHY with SGMII interface and the necessary sup-

ply voltage regulators for the PHYs sub-voltages. The

SFP port was intended to be a modular transceiver

for optical interfaces with different wavelength like

1000BASE-SX, 1000BASE-LX or for 1000BASE-T.

But today there are also implementations with a re-

verse compatibility to 10/100BASE-TX.

4.3 Generalized Structure of a Media

Converter

Simple media converters consist of two PHYs which

are connected with each other over MII. So data can

be converted from one PHY over MII to another PHY.

This hardware conﬁguration is called Back-to-Back-

converter and can be used for every Ethernet-based

communication where the data rate of the ﬁrst and

the second PHY is equal. Otherwise the slower PHY

would not be able to transport the higher amount of

data and discard data packets.

5 STRUCTURE OF THE

TECHNICA / TINYTRON

MEDIA CONVERTER

Figure 1 shows the block diagram of the Tech-

nica/tinytron BroadR-Reach-to-optical Ethernet me-

dia converter. These blocks are inﬂuencing the qual-

PECCS2014-InternationalConferenceonPervasiveandEmbeddedComputingandCommunicationSystems

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PHY

(BCM54810S)

SFP

Con.

Power

CMC

Linear

power

supply

Signal

filter

Signal

CMC

Switch

MDC

MDIO

BR/PWR Con.

SGMII

Signal

Indicators

µC

BroadR-

Reach

Figure 1: Block diagram of a Technica/tinytron optical

Ethernet-to-BroadR-Reach media converter.

ity of the BroadR-Reach signal and are explained in

the following. Arrows which are double headed show

a bidirectional information ﬂow. The thick arrows

represent the ﬂow of the information which is con-

verted from one medium to another. The location of

the blocks resembles to the layout of the circuit board.

The converter has two main connectors. One for the

digital SGMII connection to the SFP module and the

other as a lockable Tyco connector for the analog

BroadR-Reach and the power supply. To avoid dis-

tortion the power line is ﬁltered with a common mode

choke (CMC) and the supply voltage is divided to the

necessary sub voltages 3.3 and 1.2 V by linear regula-

tors. This spares ﬁltering of switched power supplies.

The analog and the digital parts are well separated

from each other. Like the power line the BroadR-

Reach signal is lead through a CMC and then ﬁltered

with a multi-stage LC-ﬁlter. Although the dimension-

ing of the ﬁlter components and the selection of the

CMC is signiﬁcant for the signal integrity, it is still

under development and requires an Non Disclosure

Agreement (NDA) from Broadcom, thus not part of

this research. After the signal is processed by the

PHY, in this case a BCM54810S with internal GMII

to SGMII converter, the SGMII is connected to the

SFP Plug to interconnect for example with the PHY

in a SFP Module with LC Connector for optical data

transmission. A simple microcontroller initializes the

BroadR-Reach PHY and reads out two dual in line

package (DIP) switches. The DIPs are used for con-

ﬁguration of common transmission parameters since

autonegotiation is not used in the car. One is the se-

lection which side is the clock source (master) or sink

(slave). The other choses if the the output power is

in half or full out mode. More about that can be

read in the data sheet of the PHY (Broadcom, 3 05).

Two LEDs show the link state and the activity of the

BroadR-Reach connection. Link and activity of the

SFP can be seen on some versions of the transceiver.

6 MEASUREMENT SETUP

6.1 Test Environment and Preset

All measurements were made in an automotive certi-

ﬁed EMC test chamber which is calibrated weekly.

Since the described media converter is used to test

and qualify a DUT, the converter itself has to ful-

ﬁl the same requirements to electromagnetic copper

bound emission. Therefore, the emission has to be

qualiﬁed with the same requirements as the tested

DUT. This EMC requirements can vary between the

projects and their client. One of these speciﬁcations

is the BMW group standard for electromagnetic com-

patibility GS 95002 (BMW Group, 4 10) and was cho-

sen because of its representativity. This standard de-

scribes several measurement setups, their ﬁelds of ap-

plication, preferences and limit lines.

It was chosen to evaluate the emission with the

stripline antenna and a measurement receiver. In this

method the DUT, in this case only the data line, is

placed under a stripline antenna which is connected

to a measurement receiver. This receiver interprets

the signal. This signal is then read out by a soft-

ware which presets the receiver, triggers the mea-

surement and logs the results. Table 1 shows the

used receiver model and measurement settings de-

ﬁned from suggestions in GS 95002. All measure-

ments were made with the Rhode & Schwarz ESC30

in Fast Fourier Transformation (FFT) mode. The de-

tectors average and peak were set which built their

result over the dwell time. The frequencies start at fs-

tart and are stepped with fstep until fstop is reached.

The IF-bandwidth of the used receiver internal input

bandpass-ﬁlter is IF-BW.

6.2 Measurement Setup

The Hardware of the test setup consists of two

BroadR-Reach nodes. A block diagram of the test

environment can be seen in ﬁgure 2. Node A (left)

and B (right) are realized with an Technica/tinytron

media converter as explained in section 5. In this

setup node A is set to master and node B to slave.

Otherwise there would be no active link between the

nodes. A and B are conﬁgured to full output power.

Both nodes were connected with a ”Dacar 609 FLR-

CUAGY 2x0.18 AX” cable from Leoni.

The nodes were supplied from outside of the chamber.

This power supply line is ﬁltered over an EMC ﬁlter

from the outside to the inside of the chamber to avoid

distortions and connected to an artiﬁcial network in-

side of the chamber to simulate in-vehicle behavior.

Since optical communication has no electromagnetic

ElectromagneticEmissionofanOptical-to-BroadR-ReachConverter

133

Table 1: Measurement receiver settings from table 9 in GS 95002.

No. Receiver Detectors fstart [Hz] fstop [Hz] fstep [Hz] If-BW [Hz] dwell time [s]

1 FFT ESCS30, 9kHz Pk, Av 500 k 2 M 3.1 k 9 k 200 m

2 FFT ESCS30 Pk, Av 2 M 30 M 3.1 k 9 k 200 m

3 FFT ESCS30 Pk, Av 30 M 1 G 49 k 12 k 100 m

emission, the SFP module is plugged in but not con-

nected with optical ﬁbers.

After the measurement setup was completely built up

and wired inside of the chamber, the media convert-

ers were plugged out from power while the external

power supply was still on and a baseline measurement

was made. This ensures correct working of the power

input ﬁlters and gives a feedback if the receivers are

working correctly. Additionally it gives a statement

about the noise ﬂoor which helps to interpret the fol-

lowing measurement. This baseline of the media con-

verter noise ﬂoor was measured with the settings from

table 1 and can be seen in ﬁgure 3. The blue line

(starts at at 30 dbu V) is the limit line suggested by

GS 95002. The black (starts at -10 dbu V) and the

red line (Start at -19 dbu V) are the detector results

for peak and average. It can be seen, that the graph

is running parallel without any high spikes. The dis-

continuity can be explained with the different receiver

settings and the resulting measurement range of the

receiver.

After the noise ﬂoor measurement showed no exter-

nal inﬂuence of the environment, the converters were

supplied with power which makes them exchange idle

packets. After a uptime of two minutes the measure-

ment was started. Two follow-up measurements did

not show a difference thus the ﬁrst results are used.

The result can be seen in ﬁgure 4 and is explained in

section 6.4.

6.3 Test Setup

• The connection speed between node A an node B

is 100 Mbit/s while using full duplex mode.

• While there is no data transmission between node

A and node B the PHYs will send idle codes,

which are a sequence of logical ones. Because

there is no difference between sending data or idle

codes, the signal on the physical layer would be

similar.

• The power requirements of the DUT are 8 to 16 V

DC with a power consumption of 2 W. Hence the

internal 3.3 V and 1.2 V are generated by linear

regulators, the supply voltage was set to 10 V to

keep the heat dissipation low.

Figure 2: Blockdiagram of the test environment. Two Tech-

nica/tinytron media converter are connectet with each other

to to interchange Idle-Codes.

Measurement: 13.03.2013 14:21:43

Continental Automotive GmbH / EMC-Laboratory Regensburg

Radiated Emissions / Development Test Result. Not for Sign-Off / TS2

EUT: ; HW: ; SW: ; DUT #

Manufacturer: Continental Automotive GmbH

Setup: Stripline-setup (2 x LISN)

Performers: Mr. Ndounokon; Mr. Eglmeier, Mr. Degueldre

Operating mode: idle code

Test plan: BMW BDC EMV Testplan Version 04

Comment:

" Noise Floor Measurement"

-No- -Receiver- -Detector(s)- -fstart [Hz]- -fstop [Hz]- -fstep [Hz]- -IF-BW [Hz]- -dwell time- -Transducer-

1 FFT ESCS30, 9kHz Pk Av 500k 2M 3,1k 9k 200ms [none]

2 FFT ESCS30 Pk Av 2M 30M 3,1k 9k 200ms [none]

3 FFT ESCS30 Pk Av 30M 1G 49k 120k 100ms [none]

-30

-20

-10

500k 1G [Hz]1M

2M 3M 5M 7M

10M

20M 30M 50M 70M

100M

200M 300M 500M 700M

GS 95002 SL PK 1

Peak

-10,1 dBµV

f= 502,6 kHz

Average

-19,3 dBµV

f= 502,6 kHz

Peaks at acceptance limit

Limit1 Limit2 Limit3 Limit4

No. Freq [Hz] Peak Avg CISPR-QP - Type

p nb

- - -

File: D:\-=MAP=-\WISES\EMV-Messungen\TS2_RE Stripline\mes\BDC-BroadR_130313S2sAap00.mes

[dBµV]

Figure 3: Baseline noise ﬂoor meashurement. Blue: Limit

line from GS 95002; Black: Peak detector result; Red: Av-

erage detector result.

6.4 Results

Figure 4 shows the ﬁnal result of the measurements.

Like in ﬁgure 3 the average and the peak emissions for

the dedicated frequencies can be seen. This time with

running media converters conﬁgured as explained in

section 6.2. With regard to the noise level in ﬁgure

3, the emission is increasing steadily from 500 kHz

to 30 MHz, where it begins to reach the fundamen-

tal frequency 33,3 MHz, mentioned in section 4. This

is the range of frequencies where the BroadR-Reach

signal ﬁlter has its lowest attenuation to let the signal

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Measurement: 13.03.2013 16:19:44

Continental Automotive GmbH / EMC-Laboratory Regensburg

Radiated Emissions / Development Test Result. Not for Sign-Off / TS2

EUT: Techniker Converter Link; HW: ; SW: EMV Link; DUT #

Manufacturer: Continental Automotive GmbH

Setup: Stripline-setup (2 x LISN)

Performers: Mr. Ndounokon; Mr. Eglmeier, Mr. Degueldre

Operating mode: EQI Messung

Test plan: BMW BDC EMV Testplan Version 04

Comment: 10V Vbat ohne Battery; ein BR-Reach und ein optical ethernet

-No- -Receiver- -Detector(s)- -fstart [Hz]- -fstop [Hz]- -fstep [Hz]- -IF-BW [Hz]- -dwell time- -Transducer-

1 FFT ESCS30, 9kHz Pk Av 500k 2M 3,1k 9k 200ms [none]

2 FFT ESCS30 Pk Av 2M 30M 3,1k 9k 200ms [none]

3 FFT ESCS30 Pk Av 30M 1G 49k 120k 100ms [none]

-30

-20

-10

500k 1G [Hz]1M

2M 3M 5M 7M

10M

20M 30M 50M 70M

100M

200M 300M 500M 700M

GS 95002 SL PK 1

Peak

11,5 dBµV

f= 30 MHz

Average

-1,3 dBµV

f= 30 MHz

Peaks at acceptance limit

Limit1 Limit2 Limit3 Limit4

No. Freq [Hz] Peak Avg CISPR-QP - Type

p nb

- - -

3 33,153M 26,8 10 - - BB 28,1 - - -

3 37,567M 23,2 9,2 - - BB 25,7 - - -

3 40,202M 21,4 9,1 - - BB 25,1 - - -

3 40,518M 22,1 8,8 - - BB 24,6 - - -

3 41,518M 20 8,5 - - BB 23,9 - - -

3 42,567M 21,7 7,9 - - BB 23,7 - - -

3 43,567M 19,8 7,3 - - BB 23 - - -

3 46,518M 19 5,6 - - BB 22 - - -

3 47,567M 17,8 5,3 - - BB 21,7 - - -

File: D:\-=MAP=-\WISES\EMV-Messungen\TS2_RE Stripline\mes\BDC-BroadR_130313S2sAap02.mes

[dBµV]

Figure 4: Result of the emission measurement. Blue: Limit

line from GS 95002; Black: Peak detector result; Red: Av-

erage detector result.

pass. The frequencies over 70 MHz follow exactly the

noise ﬂoor measurement what lets assume that the ﬁl-

ter cuts of everything from here. Over the whole mea-

surement there was no exceed of the limit line. Thus

the signal of the Technica/tinytron media converter is

GS 95002 conform with regard to copper bound emis-

sion.

7 SUMMARY AND

CONCLUSIONS

In this paper a test setup was built up to measure

the copper bound emission of the BroadR-Reach con-

nection between two identical media converters from

Technica/tinytron. The measurement receiver settings

and the limit lines were taken from the BMW Group

Standard 95002.

The results in ﬁgures 3 and 4 show that there was no

limit line exceeded during the tests. That makes the

Technica/tinytron media converters GS 95002 confor-

mant in case of copper bound emissions. Addition-

ally there is no difference between the noise level

and measurements at frequencies higher than 70 MHz

which is an indicator, that the signal ﬁlter does cut off

the internal frequencies of the converter reliably.

That leads to the conclusion, that the Tech-

nica/tinytron media converters itself do not add any

distortions to the test setup and can be used for inside

EMC chamber use. But the measured emissions are

relatively close to the limit line at about 40 MHz. A

change in the cable, connector or in the ﬁlter topol-

ogy, for example when node A and B are different,

eg node B is a DUT, could cause a signal reﬂection.

Thus an exceedance of the limit lines could be pos-

sible. Hence a further investigation has to be made

when the ﬁlter values or topologies are changed in

the setup. Optical-to-BroadR-reach media converters

with matching ﬁlters to the DUT will be important for

every future evaluation of ECUs.

The research leading to these results was supported

by Regionale Wettbewerbsfaehigkeit und Beschaef-

tigung, Bayern, 2007-2013 (EFRE) as part of the

SECBIT project (http://www.secbit.de)

REFERENCES

BMW Group (2004-10). BMW Group Standard 95002.

Broadcom (2013-05). BroadR-Reach Phyiscal Layer.

http:// www.broadcom.com/products/Physical-Layer/

BroadR-Reach-PHYs.

Bruckmeier, R. (2010). Ethernet for Automotive Applica-

tions. Freescale Technology Forum, Orlando.

Continental Engineering Services (2013-07). Conti-

nental Engineering Services. http://www.conti-

engineering.com/www/engineering services de en/

themes/ electric electronic architecture 1 en.html.

OPEN Alliance (2013-05). One Pair Ethernet.

http://www.opensig.org.

Strobl, M. (2012-10-25). Electromagnetic emissions mea-

surements and powerline communication improve-

ments.

Technica Engineering (2013-07). Technica Engi-

neering media converters. http://www.technica-

engineering.de/?page id=1701.

Verdon, A. and Tazebay, M. (2013-09). Broadr-reach archi-

tecture.

ElectromagneticEmissionofanOptical-to-BroadR-ReachConverter

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