Road vehicles — Child seat presence and orientation detection system (CPOD) — Part 2: Resonator specification

This document specifies the child seat presence and orientation detection (CPOD) resonator as part of the CPOD system. It defines the electrical and environmental requirements to be met by the resonators as a condition for CPOD compatibility.

Véhicules routiers — Système de détection de la présence d'un siège enfant et de son orientation (CPOD) — Partie 2: Spécifications relatives aux résonateurs

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ISO/TS 22239-2:2018 - Road vehicles -- Child seat presence and orientation detection system (CPOD)
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Standards Content (Sample)

Second edition
Road vehicles — Child seat presence
and orientation detection system
(CPOD) —
Part 2:
Resonator specification
Véhicules routiers — Système de détection de la présence d'un siège
enfant et de son orientation (CPOD) —
Partie 2: Spécifications relatives aux résonateurs
Reference number
ISO/TS 22239-2:2018(E)
ISO 2018

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ISO/TS 22239-2:2018(E)

© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
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ii © ISO 2018 – All rights reserved

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ISO/TS 22239-2:2018(E)

Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 CPOD resonator components . 2
5 Coil requirements . 2
6 Electrical properties . 3
6.1 Digital resonator protocol . 3
6.2 Subcarrier bitstream . 5
6.3 Modulation . 7
6.3.1 General. 7
6.3.2 Useful resonator signal, Ф (t) . 8
6.3.3 Lowpass filtering .11
6.3.4 Spectral contents of Ф (t) .11
6.3.5 The useful signal, Θ (f ,H ) .13
6.3.6 The useful signal power, P (f ,H ).13
6.3.7 Noise power, P (f ,H ) .13
6.3.8 The signal-to-noise ratio (SNR) .15
6.3.9 Definition of W(H ) .15
6.3.10 Definition of N(H ) .16
6.4 Modulation parameters .17
7 Resonator timing .19
7.1 General .19
7.2 Power-up .20
7.3 Reset .20
7.4 Relevant timing and reset parameters .21
8 Electrical and environmental parameters .22
8.1 Absolute maximum ratings .22
8.2 Operating ranges .23
8.3 Storage conditions .23
9 CPOD resonator compatibility test .23
10 Resonator environmental qualification .23
10.1 Application profile .23
10.2 Common test parameters .25
10.3 Operating states .25
10.3.1 General.25
10.3.2 Operating state A (transport and storage) .25
10.3.3 Operating state B (non-functional state) .25
10.3.4 Operating state C (functional state) .25
10.3.5 Operating state D (intermitting functional state) .26
10.4 Parametrical test and parameter checking .26
10.4.1 Parametrical test before/after every single test .26
10.4.2 Continuous parameter check .26
10.5 Qualification tests .26
10.5.1 General.26
10.5.2 Acceptance criteria .26
10.5.3 Temperature storage (transport and storage) .26
10.5.4 Low temperature durability test .27
10.5.5 High temperature operating endurance test .27
10.5.6 Power thermal cycle endurance (PTCE) .28
10.5.7 Thermal shock test .29
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ISO/TS 22239-2:2018(E)

10.5.8 Temperature cycling test, constant humidity .30
10.5.9 High temperature and humidity endurance (HTHE) .31
10.5.10  Vibration test.31
10.5.11  Mechanical shock test .33
10.5.12  Fall test, not packed .34
10.5.13  Protection against intrusion of hard bodies .34
10.5.14  Protection against intrusion of fluids .35
10.5.15  Corrosion test with gutting corrosion gas .35
10.5.16  Salt spray test .36
10.5.17  Resistance to chemical substances.36
10.6 Electromagnetic compatibility (EMC) test .38
10.6.1 General.38
10.6.2 Functional status qualification .38
10.6.3 Acceptance criteria .39
10.6.4 Community .39
10.7 Electrostatic discharge (ESD) test .47
10.7.1 Test parameters .47
10.7.2 Discharge locations . .47
10.7.3 Powered-up test .48
10.7.4 Packaging and handling test (unpowered test) .49
10.8 Magnetic field stress test .49
10.8.1 Test parameters .49
10.8.2 Test procedure .49
10.8.3 Acceptance criteria .49
10.9 Qualification flow chart .50
Annex A (normative) CPOD resonator compatibility test set-up .51
Annex B (normative) CPOD resonator compatibility test parameters .56
Annex C (normative) Continuous parameter check .59
Annex D (normative) CPOD reference resonator .62
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ISO/TS 22239-2:2018(E)

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 on 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 the following
URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 36,
Safety and impact testing.
This second edition cancels and replaces the first edition (ISO 22239-2:2009), which has been technically
revised to take account of the development in technology since the first edition was published. The
main changes compared to the previous edition are as follows:
— coil geometry parameters have changed;
— CPOD resonator protocol has changed;
— modulation parameters have been updated;
— the temperature storage test has been redefined;
— the CPOD resonator test parameters have been updated; and
— the ESD test has been updated.
A list of all parts in the ISO/TS 22239 series can be found on the ISO website.
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Road vehicles — Child seat presence and orientation
detection system (CPOD) —
Part 2:
Resonator specification
1 Scope
This document specifies the child seat presence and orientation detection (CPOD) resonator as part of
the CPOD system. It defines the electrical and environmental requirements to be met by the resonators
as a condition for CPOD compatibility.
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 10605:2008, Road vehicles — Test methods for electrical disturbances from electrostatic discharge
ISO 11452-1, Road vehicles — Component test methods for electrical disturbances from narrowband
radiated electromagnetic energy — Part 1: General principles and terminology
ISO 11452-2, Road vehicles — Component test methods for electrical disturbances from narrowband
radiated electromagnetic energy — Part 2: Absorber-lined shielded enclosure
ISO 11452-3, Road vehicles — Component test methods for electrical disturbances from narrowband
radiated electromagnetic energy — Part 3: Transverse electromagnetic (TEM) cell
ISO 20653, Road vehicles — Degrees of protection (IP code) — Protection of electrical equipment against
foreign objects, water and access
ISO/TS 22239-1:2018, Road vehicles — Child seat presence and orientation detection system (CPOD) —
Part 1: Specifications and test methods
ISO 22241-1, Diesel engines — NOx reduction agent AUS 32 — Part 1: Quality requirements
IEC 60068-2-11, Environmental testing — Part 2: Tests. Test Ka: Salt mist
IEC 60068-2-38, Environmental testing — Part 2: Tests. Test Z/AD: Composite temperature/humidity
cyclic test
IEC 60068-2-60, Environmental testing — Part 2: Tests — Test Ke: Flowing mixed gas corrosion test
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/TS 22239-1 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https: //www .electropedia .org/
— ISO Online browsing platform: available at https: //www .iso .org/obp
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ISO/TS 22239-2:2018(E)

4 CPOD resonator components
The CPOD resonator shall consist of a coil and of electronics. It might be encapsulated by a housing
as indicated in Figure 1. In order to pass the resonator compatibility test successfully, the different
components shall meet the requirements defined. The transponders shall be passive, i.e. they shall take
their energy out of the magnetic field produced by the CPOD sensor.
1 encapsulation/housing
2 electronics
3 coil
Figure 1 — CPOD resonator components
5 Coil requirements
The CPOD resonator coil shall be an air coil with an elliptical shape. The geometry of the resonator
probe coil is defined as indicated in Figure 2.
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ISO/TS 22239-2:2018(E)

P , P position vectors determined by Formula (1)
1(x,y) 2(x,y)
Figure 2 — Resonator coil geometry
The position vectors of the inner and outer shape of the coil are described by Formula (1) with
parameters as specified in Table 1:
   
x y
P = + =1 (1)
   
x y
 mm  
Table 1 — Coil geometry parameters
Dimensions in millimetres, measured at 25 °C
Parameter min. max.
x — 57,4
y — 32,8
x 53,4 —
y 28,6 —
d — 1,5
6 Electrical properties
6.1 Digital resonator protocol
By generating a modulated magnetic field that is detected in the receiving antennae of the CPOD sensor
in the seat, the resonator shall transmit a digital data protocol which is built up as indicated in Figure 3.
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ISO/TS 22239-2:2018(E)

Header: Sequence of 12 bits with logical bit value = 1.
Synchronization Sequence of three logical 0/1 transitions.
Parity bit: Odd parity for T4-, T1-bit.
Divider bit: Subcarrier divider bit:
1 → divider by 40;
0 → divider by 56, right resonator.
Child seat type: T4 . T1.
Figure 3 — CPOD resonator protocol
Additional information about the child seat is provided via the child seat type bits as defined in Table 2.
Table 2 — Child seat type classification
Type T4 T3 T2 T1 Description
0 0 0 0 0 Not allowed
1 0 0 0 1 Rear-facing child seat
2 0 0 1 0 Forward-facing child seat
Convertible child seat, resonators
3 0 0 1 1
in stiff connection with child seat
Convertible child seat, resonators
4 0 1 0 0
not connected with child seat
5 0 1 0 1 Booster cushion
6 0 1 1 0 Carry-cots
7 0 1 1 1 Not yet defined
8 1 0 0 0 Not yet defined
9 1 0 0 1 Not yet defined
10 1 0 1 0 Not yet defined
11 1 0 1 1 Not yet defined
12 1 1 0 0 Not yet defined
13 1 1 0 1 Not yet defined
14 1 1 1 0 Not yet defined
15 1 1 1 1 Not yet defined
The protocol shall be repeated cyclically if the exiting magnetic field is still present. Thus, after the T4-
bit, the next bit shall again be the first bit of the header part of the data protocol (see Figure 4).
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ISO/TS 22239-2:2018(E)

1 resonator protocol
Figure 4 — Cyclical sending of the resonator protocol
Depending on whether it is a left or a right resonator, the bit frequency of the data protocol varies as
shown in Table 3.
Table 3 — Data protocol bit frequency
Resonator type Parameter Data protocol frequency
left f f /40/8 = f /320
data,left TX TX
right f f /56/8 = f /448
data,right TX TX
6.2 Subcarrier bitstream
Every resonator protocol bit value in accordance with Figure 3 logically summarizes eight consecutive
bits of the same logical value (hereafter defined as subcarrier bits) with another, higher bit frequency
(hereafter defined as subcarrier frequency). The relation between data protocol bits and subcarrier
bits is indicated in Figure 5.
1 resonator data protocol
2 subcarrier bitstream
Figure 5 — Difference between original and resonator Manchester coding
In order to prepare the subcarrier bits for transmission, every subcarrier bit value shall be Manchester
coded, as indicated in Figure 6.
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ISO/TS 22239-2:2018(E)

1 subcarrier bit values
2 resulting Manchester code
Figure 6 — Manchester coding of subcarrier bit values
A subcarrier bit value of 1 shall cause a LOW to HIGH transition in the Manchester code pattern. A
subcarrier bit value of 0 shall cause a HIGH to LOW transition on the Manchester pattern.
Table 4 — Subcarrier bit frequency, f
Resonator type Parameter Data protocol frequency
left f f /40
subcarrier TX
right f f /56
subcarrier TX
If there is a 0 to 1 transition or a 1 to 0 transition in the resonator data protocol, the resulting Manchester
code shows a ±180° phase shift (phase shift keying, PSK).
The frequency of the subcarrier bitstream, as well as the phase angle of the concerned Manchester code,
shall be used to modulate the magnetic field generated by the resonator, e.g. Figure 7 shows the main
structure of the analogue front end of a resonator. The impedance of the LC oscillator is controlled by
the Manchester code derived by the subcarrier bitstream, e.g. a HIGH level in the Manchester code leads
to state one of the oscillators impedance (HIGH state); a low level in the Manchester code leads to state
two (LOW state) of the oscillator’s impedance.
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ISO/TS 22239-2:2018(E)

1 magnetic field
2 resonator
3 resonator oil
4 control logic
5 impedance variation of LC oscillator
Figure 7 — Exemplified electrical structure of resonator analogue front end
6.3 Modulation
6.3.1 General
The resonators shall produce a phase modulation in the receiving antenna which is demodulated by
the CPOD electronic control unit (ECU). Depending on the magnetic field supplying the resonators with
energy, these shall produce a corresponding magnetic field that assures compatibility with all CPOD-
compatible systems. The Manchester code of the bitstream specified in 6.2 shall be used to control
physically the state of modulation.
The ability of a CPOD resonator to generate a phase modulation in the receiving antenna, which can be
evaluated by the CPOD sensor, is characterized by two parameters: the parameter W determines the
ability of the resonator to produce sufficient receiving amplitude in a CPOD-compatible sensor after
demodulation; the parameter N specifies a maximum noise power at the demodulator’s output.
Both parameters are derived using the following procedure, whose blocks are explained in 6.3.2 to 6.3.10.
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ISO/TS 22239-2:2018(E)

Figure 8 — Procedure to derive W(H ) and N(H ) for magnetic field strength, H
6.3.2 Useful resonator signal, Ф (t)
Since CPOD sensors usually have a high magnetic coupling between transmitting and receiving
antennae, the useful resonator signal in the resonator magnetic field reduces to the component being
perpendicular to the exiting magnetic transmitter field, which is also flooding the receiving antennae.
The amplitude phase diagram in Figure 9 shows the relation between exciting magnetic field and
resulting resonator magnetic flux.
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ISO/TS 22239-2:2018(E)

Φ transmitter magnetic flux component supplying resonator
Φ phase angle between resonator field and resonator magnetic flux, high state of modulation
Φ amplitude of resonator magnetic flux, high state of modulation
φ phase angle between transmitter field and resonator magnetic flux, low state of modulation
Φ amplitude of resonator magnetic flux, low state of modulation
Figure 9 — Resonator amplitude phase diagram
The magnetic flux generated by the resonator, which is flooding the receiving antenna, superposes to
the part of the magnetic flux generated by the transmitting antenna, which also floods the receiving
antenna. The resulting magnetic flux, Φ , in the receiving antenna is indicated in Figure 10.
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ISO/TS 22239-2:2018(E)

φ (t) phase angle modulation in receiving antenna
Φ transmitter field component flooding receiving antenna
φ phase angle between transmitter field and transponder magnetic flux, high state of modulation
Φ amplitude of resonator magnetic flux flooding receiving antenna high state of modulation
φ phase angle between transmitter field and transponder magnetic flux, low state of modulation
Φ amplitude of resonator magnetic flux flooding receiving antenna, low state of modulation
Figure 10 — Resulting magnetic flux in receiving antenna
Only the quadrature part of the magnetic flux generated by the resonator underlies CPOD compatibility
requirements (depending on the physical realization of the resonator, the part of the magnetic flux

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