ISO 21806-9:2020

INTERNATIONAL ISO
STANDARD 21806-9
First edition
2020-10
Road vehicles — Media Oriented
Systems Transport (MOST) —
Part 9:
150-Mbit/s optical physical layer
conformance test plan
Véhicules routiers — Système de transport axé sur les médias —
Partie 9: Plan d'essais de conformité de la couche optique physique à
150-Mbit/s
Reference number
©
ISO 2020
© ISO 2020
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ii © ISO 2020 – All rights reserved

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 2
4.1 Symbols . 2
4.2 Abbreviated terms . 2
5 Conventions . 3
6 Operating conditions and measurement tools, requested accuracy .3
6.1 Operating conditions . 3
6.2 Apparatus — Measurement tools, requested accuracy . 3
7 Electrical characteristics . 5
7.1 Test according to LVDS . 5
7.2 Test according to LVTTL . 5
8 Optical characteristics . 5
8.1 Measurement of optical output power at SP2. 5
8.2 Measurement of optical input power at SP3 . 6
8.3 Measurement of pigtail fibre attenuation . 7
8.3.1 General. 7
8.3.2 Practical considerations . 9
8.4 Spectral parameters at SP2 .11
8.5 b /b detection at SP2 .11
0 1
8.6 Extinction ratio at SP2 .13
8.7 Optical overshoot and undershoot at SP2 .13
8.7.1 General.13
8.7.2 Overshoot measurement example .14
8.7.3 Undershoot (2 UI) measurement example .16
8.7.4 Undershoot (4UI) measurement example .16
8.8 Transition times at SP2 .17
8.9 Stimulus creation for SP3 .18
9 Measurement of phase variation .19
9.1 General .19
9.2 Measuring alignment jitter .21
9.3 Measuring transferred jitter .23
9.4 Test set-ups .25
9.4.1 Relevant eye mask for MOST components .25
9.4.2 SP4 Jitter measurement (AJ and TJ) .26
9.4.3 SP2 jitter measurement (AJ and TJ) .27
9.5 Crosstalk .28
9.5.1 General.28
9.5.2 Measurement set-up .28
9.5.3 Procedure .29
10 Power-on and power-off .29
10.1 General .29
10.2 Measuring EOC parameters .30
10.2.1 Measuring EOC parameters — Test set-up .30
10.2.2 Measuring EOC parameters — Signal charts.31
10.2.3 Measuring EOC parameters — Test sequences .33
10.3 Measuring OEC parameters .37
10.3.1 Measuring OEC parameters — Test set-up .37
10.3.2 Measuring OEC parameters — Signal charts.38
10.3.3 Measuring OEC parameters — Test sequences .39
11 Detecting bit rate (frequency reference) .43
12 System performance .43
12.1 General .43
12.2 SP4 receiver tolerance .43
12.3 TimingMaster delay tolerance .44
13 Conformance tests of 150-Mbit/s optical physical layer .47
13.1 Location of interfaces .47
13.2 Control signals .48
13.3 Limited access to specification points .49
13.4 Parameter overview .49
14 Physical layer verification for MOST components, MOST modules, and MOST devices .51
14.1 FOT .51
14.2 Pigtail.52
14.3 MOST device .52
14.4 Development tool .52
15 Full physical layer conformance .52
15.1 Overview .52
15.2 Consideration of FOT .52
15.3 Consideration of pigtail .52
15.4 Consideration of connector interfaces .52
15.5 Generating test signals for the IUT .53
15.5.1 General information .53
15.5.2 Test set-up for jitter measurement .53
16 Limited physical layer conformance .53
16.1 Overview .53
16.2 Generating test signals for the IUT input section SP3 .55
16.3 Analysis of test results .56
16.4 Test flow overview .56
16.5 Measurement of SP3 input signal of the IUT .57
16.6 Measurement of SP2 output signal of the IUT .58
16.7 Functional testing of wake-up and shutdown .58
17 Direct physical measuring accuracy.59
18 General remarks .61
18.1 Definition of family .61
18.2 Supplier guideline for product changes .61
18.3 Dependency of the network frame rate .62
Annex A (informative) Measuring optical signals at SP2 using averaging .63
Annex B (normative) SNR requirements for test equipment .64
Annex C (informative) Limited physical layer conformance for development tools .67
Bibliography .68
iv © ISO 2020 – All rights reserved

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 31,
Data communication.
A list of all parts in the ISO 21806 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
Introduction
The Media Oriented Systems Transport (MOST) communication technology was initially developed at
the end of the 1990s in order to support complex audio applications in cars. The MOST Cooperation was
founded in 1998 with the goal to develop and enable the technology for the automotive industry. Today,
1)
MOST enables the transport of high quality of service (QoS) audio and video together with packet data
and real-time control to support modern automotive multimedia and similar applications. MOST is a
function-oriented communication technology to network a variety of multimedia devices comprising
one or more MOST nodes.
Figure 1 shows a MOST network example.
Figure 1 — MOST network example
The MOST communication technology provides
— synchronous and isochronous streaming,
— small overhead for administrative communication control,
— a functional and hierarchical system model,
— API standardization through a function block (FBlock) framework,
— free partitioning of functionality to real devices,
— service discovery and notification, and
[3]
— flexibly scalable automotive-ready Ethernet communication according to ISO/IEC/IEEE 8802-3 .
MOST is a synchronous time-division-multiplexing (TDM) network that transports different data types
on separate channels at low latency. MOST supports different bit rates and physical layers. The network
clock is provided with a continuous data signal.
1) MOST® is the registered trademark of Microchip Technology Inc. This information is given for the convenience
of users of this document and does not constitute an endorsement by ISO.
vi © ISO 2020 – All rights reserved

Within the synchronous base data signal, the content of multiple streaming connections and control
data is transported. For streaming data connections, bandwidth is reserved to avoid interruptions,
collisions, or delays in the transport of the data stream.
MOST specifies mechanisms for sending anisochronous, packet-based data in addition to control data
and streaming data. The transmission of packet-based data is separated from the transmission of
control data and streaming data. None of them interfere with each other.
A MOST network consists of devices that are connected to one common control channel and packet
channel.
In summary, MOST is a network that has mechanisms to transport the various signals and data streams
that occur in multimedia and infotainment systems.
The ISO standards maintenance portal (https:// standards .iso .org/ iso/ ) provides references to MOST
specifications implemented in today's road vehicles because easy access via hyperlinks to these
specifications is necessary. It references documents that are normative or informative for the MOST
versions 4V0, 3V1, 3V0, and 2V5.
The ISO 21806 series has been established in order to specify requirements and recommendations
for implementing the MOST communication technology into multimedia devices and to provide
conformance test plans for implementing related test tools and test procedures.
To achieve this, the ISO 21806 series is based on the open systems interconnection (OSI) basic reference
[1] [2]
model in accordance with ISO/IEC 7498-1 and ISO/IEC 10731 , which structures communication
systems into seven layers as shown in Figure 2. Stream transmission applications use a direct stream
data interface (transparent) to the data link layer.
Figure 2 — The ISO 21806 series reference according to the OSI model
The International Organization for Standardization (ISO) draws attention to the fact that it is claimed
that compliance with this document may involve the use of a patent.
ISO takes no position concerning the evidence, validity and scope of this patent right.
The holder of this patent right has assured ISO that he/she is willing to negotiate licences under
reasonable and non-discriminatory terms and conditions with applicants throughout the world. In
this respect, the statement of the holder of this patent right is registered with ISO. Information may be
obtained from the patent database available at www .iso .org/ patents.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights other than those in the patent database. ISO shall not be held responsible for identifying
any or all such patent rights.
viii © ISO 2020 – All rights reserved

INTERNATIONAL STANDARD ISO 21806-9:2020(E)
Road vehicles — Media Oriented Systems Transport
(MOST) —
Part 9:
150-Mbit/s optical physical layer conformance test plan
1 Scope
This document specifies the conformance test plan for the 150-Mbit/s optical physical layer for MOST
(MOST150 oPHY), a synchronous time-division-multiplexing network.
This document specifies the basic conformance test measurement methods, relevant for verifying
compatibility of networks, nodes, and MOST components with the requirements specified in
ISO 21806-8.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 21806-1, Road vehicles — Media Oriented Systems Transport (MOST) — Part 1: General information
and definitions
ISO 21806-8:2020, Road vehicles — Media Oriented Systems Transport (MOST) — Part 8: 150-Mbit/s
optical physical layer
IEC 60793-1-40, Optical fibres — Part 1-40: Measurement methods and test procedures — Attenuation
IEC 61280-1-3, Fibre optic communication subsystem test procedures — Part 1-3: General communication
subsystems — Central wavelength and spectral width measurement, Method B
IEC 61280-2-2, Fibre optic communication subsystem test procedures — Part 2-2: Digital systems — Optical
eye pattern, waveform and extinction ratio measurement
IEC 61300-3-4, Fibre optic interconnecting devices and passive components — Basic test and measurement
procedures — Part 3-4: Examinations and measurements — Attenuation
2)
JEDEC No. JESD8C.01 , Interface Standard for Nominal 3 V/3.3 V Supply Digital Integrated Circuits
3)
TIA/EIA-644-A , Electrical Characteristics of Low-Voltage Differential Signaling (LVDS) Interface Circuits
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 21806-1, ISO 21806-8, and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
2) Available at https:// www .jedec .org/ .
3) Available at https:// www .tiaonline .org/ standards/ .
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
intersymbol interference
disturbance due to the overflowing into the signal element representing a wanted digit of signal
elements representing preceding or following digits
[SOURCE: IEC Electropedia 702-08-33]
4 Symbols and abbreviated terms
4.1 Symbols
--- empty cell/undefined
t time of optical signal level detection end
OSLE
t time of optical signal level detection start
OSLS
ρ frame rate
Fs
ρ bit rate
BR
4.2 Abbreviated terms
For the purposes of this document, the abbreviated terms given in ISO 21806-1, ISO 21806-8, and the
following apply.
AC alternate current
AJ alignment jitter
AWG arbitrary waveform generator
BW bandwidth
DC direct current
DCD duty cycle distortion
DSO digital sampling oscilloscope
IUT implementation under test
EMD equilibrium mode power distribution
EOC electrical optical converter
FOT fibre optic transceiver
MNC MOST network controller
NA numerical aperture
OEC optical electrical converter
PG pattern generator
PHYSTT physical layer stress test tool
2 © ISO 2020 – All rights reserved

PLL phase lock loop
POF plastic optical fibre
RMS root mean square
SDA serial data analyser
SMD surface mount device
SNR signal-to-noise ratio
SP Specification Point
THM through hole mount
TJ transferred jitter
UI unit interval
VCM common mode voltage
5 Conventions
[2]
This document is based on OSI service conventions as specified in ISO/IEC 10731 .
6 Operating conditions and measurement tools, requested accuracy
6.1 Operating conditions
Temperature range for MOST components: T = −40 °C to +95 °C according to ISO 21806-8:2020, 11.4.
A
Voltage range for MOST components: V = 3,135 V to 3,465 V according to ISO 21806-8:2020, Clause 10.
CC
NOTE There are functional requirements for the EOC within an extended voltage supply range according to
ISO 21806-8.
6.2 Apparatus — Measurement tools, requested accuracy
The following list provides state-of-the-art tools.
6.2.1 Oscilloscope
— digital sampling oscilloscope;
— sampling rate ≥10 gigasample/s;
— bandwidth ≥1,5 GHz;
— sampling memory ≥10 megasample;
— active probe (single-ended, differential).
6.2.2 High-speed OEC
— bandwidth ≥250 MHz (DC-coupled) for b /b measurement to calculate extinction ratio r ;
0 1 e2
— bandwidth ≥750 MHz (DC- or AC-coupled) for all other measurements;
— performance recommendation:
— response flatness: 1 dB (constant gain over bandwidth; linear transfer function over the optical
input range);
— low DC offset error (see 8.5).
6.2.3 High-speed EOC
— light source with a pulse shape representing a high-bandwidth emitter:
— transition time t and t below 1 ns;
r f
— overshoot greater than 1,25 of normalized amplitude;
— extinction ratio: 10 dB to 12 dB.
— light source with a pulse shape representing a low-bandwidth emitter:
— transition time t and t between 1 ns and 0,5 UI;
r f
— overshoot: no overshoot;
— extinction ratio: 10 dB to 12 dB.
6.2.4 Optical power meter
— accuracy: at least ±0,25 dB;
— accuracy optical power meter and SP2 adaptor: at least ±0,5 dB;
— wavelength: 650 nm;
— range: at least -60 dBm to 0 dBm;
— trigger input (for timing measurements).
6.2.5 Ampere meter
— accuracy ≤2 µA;
— trigger input (for timing measurements).
6.2.6 Pattern generator for generating MOST150 oPHY stress pattern
— bandwidth 300 Mbit/s;
— trigger output (for timing measurements).
6.2.7 Optical attenuator
— attenuation up to 40 dB;
— preferably attenuation via grey filter, not via air gap.
6.2.8 Optical Y–coupler.
6.2.9 Optical spectrometer
— resolution ≤1 nm;
4 © ISO 2020 – All rights reserved

— spectral range at least 500 nm to 800 nm.
7 Electrical characteristics
7.1 Test according to LVDS
Testing of MOST devices or MOST components shall be performed according to the measurement
methods and set-ups specified in TIA/EIA-644-A. Parameters and their respective limits are also
derived from TIA/EIA-644-A, with the exception of common mode voltage (V ) as specified in
CM
ISO 21806-8:2020, 12.1.
7.2 Test according to LVTTL
Testing of MOST devices or MOST components shall be performed in accordance with JEDEC No.
JESD8C.01.
8 Optical characteristics
8.1 Measurement of optical output power at SP2
Figure 3 shows the schematic of an optical power meter. This measurement adaptor allows the test of
parameter P considering the power within a far field angle of 30° (NA = 0,5) and a diameter of 1,0 mm.
opt2
The optical power at SP2 is transferred by a glass fibre with a numerical aperture of greater than
0,5, a core diameter of 1 000 µm, and a typical length of 30 mm. An aperture between glass fibre and
photo detector confines the transferred beam to the required numerical aperture of 0,5. The size of
the aperture depends on the distance between glass fibre and the aperture (see Figure 4). The end face
of the glass fibre shall be polished to avoid scattering and a conversion of the beam waist from SP2 to
the end of the glass fibre. The glass fibre is mounted into a ferrule, which can be inserted into an SP2-
contact of a MOST device for measuring the optical power at SP2 (MOST compatible ferrule, i.e. derived
from connector drawing).
Key
1 glass fibre, D = 1 mm, NA ≥ 0,5
2 NA = 0,5
3 large area photo detector
4 MOST compatible ferrule
Figure 3 — Schematic of optical power meter
Figure 4 shows the calculation of aperture size d .
B
Key
1 aperture size d : see Formula (1)
B
2 photo detector
3 aperture
4 glass fibre
5 distance X between the glass fibre and the aperture
Figure 4 — Calculation of aperture size d
B
IMPORTANT — It should be ensured that the size of the photo detector is large enough to receive
all the light after the aperture.
dc=+23××X tan()0° (1)
B
where
d is the aperture size;
B
X is the distance between the glass fibre and the aperture;
c is the diameter: 1 mm.
8.2 Measurement of optical input power at SP3
The optical power measurement set-up is given in Figure 5. This measurement allows the testing of the
parameter P considering the power within a far field angle of 30° (NA = 0,5) and a diameter of 1,0 mm.
opt3
Figure 5 shows the optical power measurement set-up for SP3.
6 © ISO 2020 – All rights reserved

Key
1 glass fibre, D = 1 mm, NA ≥ 0,5
2 NA = 0,5
3 large area photo detector
4 MOST ferrule
5 50 µm to 100 µm; see connector interfaces in ISO 21806-8
6 1 mm POF cable harness
Figure 5 — Optical power measurement set-up for SP3
A glass fibre and an aperture transfer the measured optical power-on a large area photo detector. For
description and the calculation base for the aperture see 8.1.
In ISO 21806-8, P is the value of the optical power, when the incoming signal passes the receiving
opt3
contact end face.
Compared to the glass fibre used in the measurement set-up, the surface quality of a real SP3 contact
might be worse. This might result in a lower input power than shown by the measurement. This small
mismatch is covered by the specified connection loss. The axial offset shown in Figure 5 considers a
requirement defined in the connector interface drawings (see ISO 21806-8).
8.3 Measurement of pigtail fibre attenuation
8.3.1 General
Attenuation of a pigtail fibre is measured using the insertion method, which shall be in accordance
with IEC 61300-3-4. The measurement set-up consists of a light source, a mode mixer, which shall be in
accordance with IEC 60793-1-40, and a launching fibre for generating the stimulus signal. For detection
of optical power, a power meter is used. The connection between IUT and power meter is realized with
a secondary launching fibre or an equivalent arrangement.
The measurement is performed in two steps. The first step consists of the measurement of the initial
power level P (see Figure 6) while the second step provides the measurement of the power level
Initial
with the connected pigtail fibre P (see Figure 7). Figure 6 shows the measurement of P .
IUT Initial
Key
1 launching fibre #1
2 launching fibre #2
3 connector
Figure 6 — Measurement of P
Initial
Figure 7 shows the measurement of P .
IUT
Key
1 launching fibre #1
2 launching fibre #2
3 connector
Figure 7 — Measurement of P
IUT
The optical power is measured in logarithmic scale (dBm). The attenuation of a pigtail fibre [see
Formula (2)] is measured using the insertion method between P and P expressed in (dB).
Initial IUT
8 © ISO 2020 – All rights reserved

AP=−P (2)
PigTailIUT Initial
where
A is the attenuation of the pig tail;
PigTail
P is the power implementation under test;
IUT
P is the power initial.
Initial
8.3.2 Practical considerations
The optical power levels are measured within a diameter of 1 mm and an acceptance angle of 30°.
This represents the coupling characteristic of a POF with NA = 0,5, which is typically used in the wire
harness. The light source in combination with the mode mixer and the launching fibre #1 creates the
equilibrium mode power distribution (EMD). The pigtail fibre is tested using the EMD launch condition.
The secondary launching fibre is used for interfacing with the pigtail fibre. It would also eliminate
power above NA = 0,5, if it exists. As long as the pigtail fibre does not modify the power distribution, the
filter function of set-up the secondary launching fibre is not required. For simplification, the launching
fibre #2 can be replaced by an SP2 adaptor or equivalent set-ups.
For testing, optical terminals are created for interfacing with the SP2/SP3 contact geometry on one
side and with the ferrules for the SMD transceiver on the other side. The contact shape of the FOT-
side ferrules provides different diameters (mechanical coding). Apart from that, the SP2/SP3 contacts
have different contact dimensions. According to IEC 61300-3-4 an adaptor may be used (known as
“temporary joint”) for coupling of these differently shaped ferrules.
Figure 8 shows the usage of adaptors for matching different contact shapes.
Key
1 launching fibre #1
2 launching fibre #2
3 adaptor “temporary joint”
Figure 8 — Usage of adaptors for matching different contact shapes
Figure 9 shows an example of a mode mixer (D = 42 mm, d = ~4,5 mm, number of turns = 10, length of
optical fibre ≤15 m).
Key
d distance
D diameter
Figure 9 — Example of a mode mixer
10 © ISO 2020 – All rights reserved

8.4 Spectral parameters at SP2
Centre wavelength and spectral width
ISO 21806-8 defines the wavelength spectrum of a transmitter with the parameter centre wavelength
and spectral width. This is necessary to consider possible spectral asymmetries of state-of-the-art light
sources.
The measurement procedure shall be in accordance with IEC 61280-1-3 with the following constraints:
— measurement resolution is ≤1 nm;
— SNR for the measurement equipment is ≥20 dB;
— SNR determines the part, which may be cut from the spectrum; and
— dark calibration.
Measurement resolution shall be ≤1 nm:
— SNR for the measurement equipment at least 20 dB;
— SNR determines the part which may be cut from the spectrum;
— dark calibration necessary.
Figure 10 shows an example of how to determine centre wavelength and spectral width.
Key
X wavelength [nm]
Y relative optical power [dB]
1 measured values in grey zone are set to zero
Figure 10 — Example determination of spectral parameters
8.5 b /b detection at SP2
0 1
To determine b /b levels, the pattern generator shall generate the MOST150 oPHY stress pattern. At
0 1
least 500 pulses (5 UI or 6 UI) shall be extracted out of the measured data. Extraction can be done by
triggering on pulse-width ranges or by software-based selection on a prior acquired waveform. b is
the statistical mean of all amplitude samples lying in the slice between t and t for all acquired
OSLS OSLE
high pulses. b is the statistical mean of all amplitude samples lying in the slice between t and t
0 OSLS OSLE
for all acquired low pulses. t and t are specified in Table 1.
OSLS OSLE
Table 1 — Optical signal level measurement interval
Measurement region Value Unit
t 2,5 UI
OSLS
t 4,0 UI
OSLE
The measured optical amplitudes b and b are an integral part of further measurements at SP2. The
1 0
accuracy of b /b detection determines the accuracy of such a linked measurement. Any variation in a
0 1
measurement set-up or in the environmental conditions has an impact on b and b . Therefore, b /b
1 0 0 1
detection should be a part of the linked measurement.
For b /b detection, DC-coupled or AC-coupled measurement OECs may be used but there are
0 1
restrictions given due to the corresponding measurement. Table 2 shows the parameters, which are
based on b /b and the restriction for the measurement OEC.
0 1
Measurement should compensate the DC offset of a DC-coupled OEC using dark calibration. For accurate
measurement results, the signal-to-noise ratio (SNR) shall be in accordance with Annex B.
Table 2 — Restrictions for measurement OECs
Parameter Symbol Restriction Usage of b and b
0 1
Extinction ratio r DC-coupled, BW > 250 MHz Calculation, ratio of b to b
e2 1 0
DC-coupled, BW > 750 MHz
Determination of the 20 % and 80 %
Transition times t , t
r2 f2
amplitudes
AC-coupled, BW > 750 MHz
DC-coupled, BW > 750 MHz
Determination of the trip-point, 50 %
Transferred jitter J
tr2
amplitude
AC-coupled, BW > 750 MHz
DC-coupled, BW > 750 MHz
Normalization of the amplitude for
Alignment jitter ---
adjusting the eye mask
AC-coupled, BW > 750 MHz
DC-coupled, BW > 750 MHz
Overshoot/ Normalization of the amplitude for
---
undershoot adjusting the masks
AC-coupled, BW > 750 MHz
In the case of using an AC-coupled measurement OEC for all measurements excluding extinction ratio,
a DC-coupled OEC with lower bandwidth-setting such as used for MOST25 oPHY can be reused for
determination of extinction ratio. See 6.2 for more detailed OEC requirements.
Figure 11 provides an example of how to measure b and b by a histogram method.
0 1
12 © ISO 2020 – All rights reserved

Key
X normalised timeline
Y normalised amplitude
1 histogram box
Oscilloscope measurements: b = 192,37 mV, b = −246,46 mV, ρ = 147,455 989 Mbit/s.
1mean 0mean BR
Figure 11 — Detection of b and b
0 1
Measuring optical signals at SP2 using averaging is described in Annex A.
8.6 Extinction ratio at SP2
Extinction ratio r is calculated based on the measured optical levels for b and b as described in 8.5
e2 1 0
by using a DC-coupled OEC according to Table 2.
The extinction ratio r is given with Formulae (3).
e2
b
 
r =×10 log (3)
 
e2
b
 0 
where
r is the extinction ratio;
e2
b is the optical signal level when a logic 0 is transmitted;
b is the optical signal level when a logic 1 is transmitted.
For measuring b and b , a DC-coupled OEC according to Table 2 shall be used. The measurement
1 0
procedure shall be in accordance with IEC 61280-2-2.
8.7 Optical overshoot and undershoot at SP2
8.7.1 General
The optical pulse shape of an SP2 signal is tested with a parameterized mask. The mask parameters
are given in normalized amplitude, which is based on the measured optical signal levels b and b . Time
0 1
parameters are specified in units of UI and the origin for the timescale is defined from the midpoint
of the rising or falling edge of the signal. Overshoot and undershoot measurements contain only one
edge of a pulse class, which forms the trigger edge. Timing variations that might be included in the data
stream and be visible on subsequent edges are excluded from this measurement. The timing corridor
given around the trigger point (overshoot H , C , undershoot G , R given in this document) serves for
O O U U
tolerating noise coming from the measurement OEC. The test case shall verify that the measured signal
does not touch the keep-out areas of the masks.
There are two basic strategies to perform the measurement:
a) Draw a mask that is adjusted in vertical and horizontal scale to the conditions (b , b , timing
1 0
resolution) given by a particular measured waveform.
...