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Technical requirements for TAA to certify UTC-traceability

ICS 35.030;35.240.60 Reference number : JIS X 5094 : 2019 (E)

JAPANESEINDUSTRIALSTANDARD

Translated and Published byJapanese Standards Association

JIS X 5094 : 2019 (NICT)

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Date of Establishment: 2011-05-20

Date of Revision: 2019-03-20

Date of Public Notice in Official Gazette: 2019-03-20

Investigated by: Japanese Industrial Standards Committee

Standards Board for IEC area

Technical Committee on Information

JIS X 5094 : 2019, First English edition published in 2019-12

Translated and published by: Japanese Standards Association Mita MT Building, 3-13-12, Mita, Minato-ku, Tokyo, 108-0073 JAPAN

In the event of any doubts arising as to the contents,

the original JIS is to be the final authority.

JSA 2019 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, withoutpermission in writing from the publisher.

Printed in Japan HN



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Contents

Page

Introduction ································································································· 1

1 Scope ································································································· 1

2 Normative references ············································································ 1

3 Terms and definitions ··········································································· 2

4 Symbols and abbreviated terms ······························································ 4

5 General ······························································································ 4

6 Time traceability chains and certification of traceability ···························· 5 6.1 Time dissemination and traceability chains ·············································· 5 6.2 Time auditing of TSA clock by TAA ························································· 5

7 Technical requirements for TAA ····························································· 6 7.1 Policy on requirements for TAA ······························································ 6 7.2 Requirements for TAA clock ·································································· 6 7.3 Requirements for time audit ·································································· 8 7.4 Requirements for time dissemination ······················································ 9 7.5 Other requirement ·············································································· 10

Annex A (informative) Relation between time offset certificate and existing national standards ····················································· 11

Annex B (informative) Traceability chains and required accuracy ····················· 12

Annex C (informative) Examples of TAA-based trusted time source schemes from ITU-R TF.1876 ··················································· 14

Annex D (informative) Required accuracy and frequency stability of the ref-erence clock ······························································ 15

Bibliography ······························································································· 16

Annex JA (informative) Comparison table between JIS and corresponding International Standard ············································· 17



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This Japanese Industrial Standard has been revised by the Minister of Economy, Trade and Industry through deliberations at the Japanese In-dustrial Standards Committee as the result of proposal for revision of Japanese Industrial Standard submitted by National Institute of Infor-mation and Communications Technology (NICT)/Japanese Standards Association (JSA) with the draft being attached, based on the provision of Article 12 Clause 1 of the Industrial Standardization Law applicable to the case of revision by the provision of Article 14.

Consequently JIS X 5094:2011 is replaced with this Standard.

This JIS document is protected by the Copyright Law.

Attention is drawn to the possibility that some parts of this Standard may conflict with patent rights, applications for a patent after opening to the public or utility model rights. The relevant Minister and the Japanese Industrial Standards Committee are not responsible for identifying any of such patent rights, applications for a patent after opening to the public or utility model rights.

Foreword



JAPANESE INDUSTRIAL STANDARD JIS X 5094 : 2019


Technical requirements for TAA to certify UTC-traceability

Introduction

This Japanese Industrial Standard was established in 2011, and has been revised this time with the aim of harmonizing its contents with ISO/IEC 18014-4 : 2015, with some modifications of the technical contents to reflect the needs and conditions unique to Japan.

The dotted underlines indicate changes from the corresponding International Stand-ard. A list of modifications with the explanations is given in Annex JA.

This Standard describes an overall architecture for providing trusted time to the time-stamping authority (TSA) and specifies technical guidelines to guarantee its cor-rectness through the use of the time assessment authority (TAA).

1 Scope

This Standard

— defines the functionality of the time assessment authority (TAA),

— describes an overall architecture for providing the time to the time-stamping au-thority (TSA) and to guarantee the correctness of it through the use of the TAA, and

— gives technical guidelines for the TAA to provide, and to provide assurance in, a trusted time source to the TSA. NOTE The International Standard corresponding to this Standard and the

symbol of degree of correspondence are as follows. ISO/IEC 18014-4 : 2015 Information technology — Security techniques

— Time-stamping services — Part 4 : Traceability of time sources (MOD) In addition, symbols which denote the degree of correspondence in the

contents between the relevant International Standards and JIS are IDT (identical), MOD (modified), and NEQ (not equivalent) according to ISO/IEC Guide 21-1.

2 Normative references

The following standards contain provisions which, through reference in this text, constitute provisions of this Standard. The most recent editions of the standards (in-cluding amendments) indicated below shall be applied.

ISO/IEC 18014-1 Information technology — Security techniques — Time-stamping services — Part 1 : Framework

ITU-R TF.1876 Trusted time source for Time Stamp Authority



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3 Terms and definitions

For the purpose of this Standard, the following terms and definitions apply.

3.1

accuracy

closeness of the agreement between the result of a measurement and the true value of the measurand (ITU-R TF.686-3 : 2013, ANNEX 1)

NOTE Accuracy is generally characterized by the overall uncertainty of a measured value.

3.2

leap second

intentional time step of one second used to adjust UTC to ensure approximate agree-ment with UT1 (ISO 8601 : 2004, 2.2.2)

3.3

measurement

process of experimentally obtaining one or more quantity values that can be reasonably attributed to a quantity (TS Z 0032 : 2012, 2.1)

3.4

second

basic unit of time or time interval that is equal to the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of caesium-133 (JIS Z 8000-3 : 2014, 3-7.a)

3.5

time assessment authority, TAA

entity which audits the time of the TSA clock and may also disseminate time to TSA

3.6

TAA clock

clock system of the TAA, used for time audit and time dissemination

3.7

time audit

audit of the time of downstream clocks in time traceability chains in order to check that it is consistent within the required accuracies

3.8

time dissemination

distribution of a time signal from one location to another



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3.9

time offset certificate

certificate issued by a TAA to certify the measured time offset of a TSA clock with re-spect to the TAA clock

3.10

time-stamping service

service that provides proof for existence of a data item before a particular point in time (JIS X 5063-1 : 2005, 3.3)

3.11

time-stamping authority, TSA

trusted third party trusted to provide a time-stamping service (ISO/IEC 18014-1 : 2008, 3.17)

3.12

time-stamp token, TST

data structure containing a verifiable cryptographic binding between a data item’s representation and a time-value (ISO/IEC 18014-1 : 2008, 3.15)

NOTE A time-stamp token can also include additional data items in the bind-ing.

3.13

time traceability chain

chain consisting of a sequence of reference clocks starting with UTC(k), used to relate the time from an end user to a timing centre

3.14

timing centre

organization with the means to disseminate the UTC(k) time to a TSA with the re-quired accuracy

NOTE The UTC(k) generated by the timing centre can be used in real time and its time difference from UTC is regularly published by the BIPM (the Bureau International des Poids et Mesures).

3.15

traceability

property of the result of a measurement or the value of a standard whereby it can be related to stated references, usually national or international standards, through an unbroken chain of comparisons all having stated uncertainties (ITU-R TF.686-3 : 2013, ANNEX 1)

3.16



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TSA clock

clock of the TSA, which generates the time information included in the TST

3.17

UTC

time scale maintained by the Bureau International des Poids et Mesures (BIPM) and the International Earth Rotation and Reference Systems Service (IERS) that forms the basis of a coordinated dissemination of standard frequencies and time signals

NOTE UTC is Coordinated Universal Time defined by ITU-R (ISO 19108 : 2002, 4.1.3).

3.18

UTC(k) [UTC(k)]

time scale realized by institute “k” and kept in close agreement with UTC, with the goal to be within ±100 ns, according to Recommendation S5 (1993) of the Consultative Committee for the Definition of the Second (ITU-R TF.536-2 : 2003, 2)

4 Symbols and abbreviated terms

For the purpose of this Standard, the following abbreviations apply :

GNSS Global Navigation Satellite System

GPS Global Positioning System

NMI National Measurement Institute

NTP Network Time Protocol

OID Object Identifier

TTP Trusted Third Party

URL Uniform Resource Locator

5 General

In time-stamping services, the TSA clock used to create TST is required to be syn-chronized with UTC within the declared accuracy, and shall be managed so as to guarantee the correctness of the time parameter included in the TST. The TAA certi-fies the traceability of the time reference of the TSA to the time scale of UTC(k) pro-vided by a timing centre and may, optionally, distribute time information to the TSA. The function of the TAA may be performed by a timing centre or by a TTP.

As for time-stamping services, those specified in ISO/IEC 18014-1 shall be referred to. As for functionalities of the TAA, those defined in ITU-R TF.1876 shall be referred to.

This Standard describes an overall architecture for providing accurate and traceable time to the TSA and for certifying the traceability of the time of the TSA to UTC(k). It also addresses technical requirements for the TAA :



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a) to provide certification to the TSA by auditing that the time used in the TSA is within the required accuracy, and

b) to distribute time information to the TSA if the TAA operates in time dissemina-tion mode.

In Japan, UTC(k) is established by National Institute of Information and Communi-cations Technology (NICT); for the purpose of this Standard, UTC(k) in Clause 7 refers to UTC(NICT).

6 Time traceability chains and certification of traceability

6.1 Time dissemination and traceability chains

Timing centres can disseminate their UTC time scale by broadcast over a radio, tel-ephone or network path as services to end users. These services allow end users to connect to a timing centre and to establish a time traceability chain.[12] The TSA, as an end user, uses time signals from the clock located upstream in the chain as a refer-ence signal. The chain thus enables traceability of a time signal to UTC(k).

The TSA clock and the TAA clock are located downstream from the timing centre on such time traceability chains, and the TAA clock is located upstream from the TSA clock when the TAA operates in time dissemination mode, as described in 6.2.

Traceability chains can also be established through time signals not controlled by a timing centre, provided that an NMI monitors and compares these signals to its UTC time scale.[12] This type of traceability chain is realized by using a certified GNSS timing receiver. The TSA can use a local oscillator controlled via the timing signal from the receiver as a traceable reference time source for the TSA clock. In this case, the timing centre referred to by the TAA is usually different from the NMI associated with the GNSS, as shown in case d) of Figure C.1.

The type of broadcast services used depends on the required accuracy for down-stream clocks in the chain.

The NTP[2] can be used to synchronize clocks over computer networks.

6.2 Time auditing of TSA clock by TAA

The role of the TAA is to audit that the TSA clock synchronized with UTC(k) is traceable to UTC(k) within the required accuracy and to provide a time offset certifi-cate (see 7.3.5) asserting traceability to the TSA. The architecture specified in this Standard provides time auditing by using the TAA in the following way.

The TAA maintains synchronization of its clock with UTC(k) by using disseminated time from a timing centre as described in 6.1. Alternatively, the TAA clock can be di-rectly controlled by a timing centre if the TAA is operated by the timing centre. The TAA provides assurance of traceability chains by periodically measuring the time offset between UTC(k) and the TAA clock, and between the TAA clock and the TSA clock. The TAA records the measured time offset and issues a time offset certificate to the TSA.

The TAA may distribute time information to the TSA using this synchronized TAA



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clock, and such an arrangement can also be classified into one of the time traceability chains, as described in 6.1.

A block diagram of the architecture is given in B.1. NOTE Examples of TAA-based trusted time source schemes specified in ITU-R

TF.1876 are given in Annex C.

7 Technical requirements for TAA

7.1 Policy on requirements for TAA

This Standard stipulates the minimum necessary requirements to make it possible for the TAA to certify that time values in the TST issued by the TSA should be accu-rate to within ±1 s of UTC(k). The permitted margin of error of ±1 s allows for problems that might arise from the introduction of a leap second.

Clause 7 provides requirements for the TAA that also disseminates time to the TSA. Requirements related to time dissemination given in 7.4 are not applicable to the TAA operating in time auditing mode only.

The accuracy required for the TAA clock and the TSA clock with respect to UTC(k) and the accuracy required for time offset measurement of the TSA clock are defined and quantified in this Standard. The TAA clock comprises a reference clock, a time au-diting unit and an optional time dissemination unit. The time source used by both units is the reference clock. The accuracy of the TAA clock refers to the accuracy of the time value output at the interface point of the time auditing unit and the time dissem-ination unit, and this output time is referred to as the disseminated time of the TAA clock. Similarly, the accuracy of the TSA clock refers to the accuracy of the time value output at its interface point (see Figure B.2).

The required accuracy of the disseminated time of the TAA clock is determined so as to make its time offset to UTC(k) negligible. For the permitted margin of error of ±1 s, the required accuracy of the disseminated time of the TAA clock is determined to be one tenth of the average accuracy error of ±500 ms of the TSA clock. Both the required accuracy of time offset measurement and the required accuracy of the reference clock are determined in the same way.

The clock time error of the TAA caused by the reference clock frequency instability over the time offset measurement interval of the TSA clock shall be negligible com-pared to the accuracy of the reference clock. Specifically the time error of the TAA shall be less than one tenth of the accuracy of the reference clock.

NOTE 1 An atomic clock or an oven crystal clock is commonly used as a refer-ence oscillator in actual services to meet the accuracy required of the TSA clock.

NOTE 2 The accuracy required for the TAA clock and the TSA clock and the ac-curacy required for time offset measurement in this Standard are shown in B.2.

7.2 Requirements for TAA clock



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7.2.1 General

The requirements specified in 7.2.2 to 7.2.6 apply to both time auditing and time distributing.

7.2.2 Configuration of TAA clock

The configuration of the TAA clock shall meet the following requirements.

a) The TAA clock shall consist of a reference clock, a time auditing unit, and option-ally a time dissemination unit. The time auditing unit and time dissemination unit shall use the reference clock as a time source.

b) The TAA shall employ a redundant configuration for the implementation of the reference clock, incorporating two or more clocks.

7.2.3 Time synchronization with UTC(k)

Time synchronization shall meet the following requirements.

a) The reference clock of the TAA clock shall be synchronized with UTC(k) within suf-ficient accuracy so as to meet the requirements specified in 7.2.4.

b) The TAA shall specify the time synchronization policy with UTC(k) and disclose its OID or URL.

c) It is recommended that the TAA make reference to another time source (e.g. GPS) in addition to UTC(k) in preparation for extraordinary situations, especially if the TAA operates in time dissemination mode. NOTE A TAA operating in time auditing mode only can abort audit operations

when its time source fails.

7.2.4 Accuracy of TAA clock

The accuracy of the TAA clock shall meet the following requirements.

a) The clock time error caused by reference clock frequency instability over the time offset measurement interval, typically several hours, of the TSA clock shall be less than one tenth of the accuracy of the reference clock which is better than ±5 ms from b). For more details, see Annex D.

b) The accuracy of the reference clock shall be more than ten times better than the accuracy of time distribution and the accuracy of time offset measurement, both of which are specified to within ±50 ms in 7.4.4 c) and 7.3.4 c), respectively.

7.2.5 Time offset measurements and retention of data

Time offset measurements and retention of measured data shall meet the following requirements.

a) The TAA shall measure the time offset between UTC(k) and the reference clock by the GPS common view method[13] or an equivalent method and shall retain meas-ured data. NOTE Other methods currently available are, e.g, the GPS all-in-view method

[14] and the satellite two-way comparison method [15].



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b) The TAA shall disclose relevant measured data to subscribers and their related persons as needs arise.

7.2.6 Records of instrument manipulation and their retention

The TAA shall record instrument manipulation (e.g. GPS receivers) relating to time offset measurements and retain their records.

7.3 Requirements for time audit

7.3.1 General

The requirements specified in 7.3.2 to 7.3.7 apply to time auditing of the TSA clock by the TAA.

7.3.2 Time audit policy

The TAA shall specify the time audit policy for TSA clocks and disclose its OID or URL.

7.3.3 Authentication of TSA clock

The TAA shall use a communications protocol by which a TSA clock to be time-audited can be identified and authenticated.

7.3.4 Measurements of time offset

The measurement of time offset shall meet the following requirements.

a) The TAA shall confirm that the adopted method for time offset measurements is valid and shall document it. NOTE It is preferable to use generally accepted methods for time offset meas-

urements such as those published in public standards and journals of acknowledged technology institutes, or those published in refereed aca-demic journals.

b) The TAA shall disclose the accuracy of time offset measurements between the TAA clock and the TSA clock; the TAA shall also disclose the time interval between suc-cessive time offset measurements.

c) The accuracy of time offset measurements shall be within ±50 ms, including net-work delay jitter.

7.3.5 Time offset certificates

The issuance of time offset certificates shall meet the following requirements.

a) The time offset certificate shall include the following fields, with the information in 6) being optional :

1) identifier for the TAA : name and/or other identifier for the TAA which issues the time offset certificate;

2) identifier for the TSA : name and/or other identifier for the TSA to which the TAA issues the time offset certificate;

3) ntpTime : time at which certification took place;



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4) offset : current offset of the TSA clock;

5) delay : path propagation delay;

6) leapSecondInfo : adjustment information for a leap second. NOTE The relationship between the above and existing national standards

is described in Annex A.

b) The TAA shall issue certificates to the TSA at appropriate intervals.

c) An issuance interval of time offset certificates shall be included in the time audit policy.

NOTE It is preferable that the TAA issues certificates at an interval of less than 24 h.

7.3.6 Retention of records

The TAA shall retain issued time offset certificates and records of their issue.

7.3.7 Measures against extraordinary time discrepancy of TSA clock

The TAA shall notify the TSA concerned regarding a loss of accuracy, if the TAA de-tects jumps or drifts of the TSA clock outside the stated accuracy.

7.4 Requirements for time dissemination

7.4.1 General

The requirements specified in 7.4.2 to 7.4.5 apply to time dissemination to the TSA from the TAA.

7.4.2 Time dissemination policy

The TAA shall define the time dissemination policy to TSA clock and shall disclose its OID or URL.

7.4.3 Authentication of TSA clock

The TAA shall use a communications protocol by which the TSA clock to be time- disseminated can be identified and authenticated.

7.4.4 Time dissemination control

The time dissemination control shall meet the following requirements.

a) The TAA shall achieve accountability that the adopted method for time dissemina-tion control is valid, and shall document the method.

NOTE It is preferable to use generally accepted methods for time dissemina-tion control such as those published in public standards and journals of acknowledged technology institutes, or those published in refereed academic journals.

b) The TAA shall declare the accuracy of time dissemination between the TAA clock and the TSA clock.

c) The accuracy of the disseminated time of the TAA clock shall be maintained within ±50 ms.



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7.4.5 Measures against falsification of disseminated time

The TAA shall ensure that the channel used for disseminating the time between the TAA and the TSA is integrity-protected.

7.5 Other requirement

The TAA shall provide appropriate measures to ensure that clock synchronization with UTC(k) is maintained when a leap second occurs, as notified by the appropriate body.



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Annex A (informative) Relation between time offset certificate and existing

national standards

This Annex describes the relationship between the time offset certificate discussed in 7.3.5 and examples of such certificates from existing national standards.

A.1 Time Offset Certificate of this Standard

The time audit certificate in the 2011 edition of this Standard is formatted as an ISO/IEC 9594-8 [7] attribute certificate version 2.

Field in 7.3.5 Field in a time offset certificate for JIS X 5094 : 2011 Identifier for TAA Issuer field of the attribute certificate Identifier for TSA Holder field of the attribute certificate ntpTime ntpTime field of TimingMetrics attribute in the attribute certificate Offset offset field of TimingMetrics attribute in the attribute certificate Delay delay field of TimingMetrics attribute in the attribute certificate leapSecondInfo leapEvent field of TimingMetrics attribute in the attribute certificate

A.2 ANSI X9.95 Time Calibration Report

The time calibration report of ANSI X9.95[1] is formatted using ASN.1[11] or XML.

Field in 7.3.5 Field in a time calibration report of ANSI X9.95 Identifier for TAA tseInfo field of TimeCalibrationReport Identifier for TSA tsaInfo field of TimeCalibrationReport ntpTime ntpTime field of TimingMetrics of TimeCalibrationReport Offset offset field of TimingMetrics of TimeCalibrationReport Delay delay field of TimingMetrics of TimeCalibrationReport leapSecondInfo leapSecond field of TimingMetrics of TimeCalibrationReport



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Annex B (informative) Traceability chains and required accuracy

B.1 Time traceability chains

Time traceability chains from the timing centre to the TSA are illustrated in Figure B.1, where the flow of the traceability chain is shown by the dotted line.

Note a) A TSA can select the time dissemination paths.

Figure B.1 Time traceability chains

B.2 Accuracy required for TAA clock and TSA clock

The accuracy required for the TAA clock and the TSA clock, and the accuracy re-quired for time offset measurement with respect to UTC(k), are illustrated in Figure B.2.

TSA

TAA

UTC(k1)

UTC(kn)

UTC

UTC(k2)

UTC(ki)

Timing centre

UTC(k) : Time scale realized by the institute “k”

Flow of traceability chainRecord of measured offset

Time dissemination

Time disseminationa)

Time disseminationa)

Time offsetmeasurement Time offset

certificate

TAA clock

Time audit

Time offsetmeasurement

TSA clock



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時刻配信

UTC(k) TSA時計

TAA時計

時刻配信

基準時計配信時刻

イン

ター

フェ

イス

点での

時刻

TST生成

精度 ≦ 50 ms

精度 ≦ 1 s (注: タイムスタンプの要件)

時刻差測定精度 ≦ 50 ms

Figure B.2 Example of calculations of required accuracies

TSA clock

TAA clock

Reference clock Disseminated time

Time dissemination Time dissemina-tion

Accuracy 50 ms

Measurement accuracy of offset 50 ms

Accuracy 1 s (Note : Time stamp requirement)

TST issuance

Tim

e at

inte

r-fa

ce p

oint

Tim

e at

inte

rfac

e po

int



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Annex C (informative) Examples of TAA-based trusted time source schemes from

ITU-R TF.1876

UTC(k)

タイミングセンタ

TSA 信頼できる第三者

信頼できる第三者

TAA

UTC(k)

TAA

TSA


TSA

UTC(k)


TAA

TSA

TAA UTC(k)

UTC(I)

TAA タイムアセスメント機関TSA タイムスタンピング機関

配信

監査

a) b)

c) d) ITU-R TF.1876から引用



信頼できる第三者タイミングセンタ



Figure C.1 Examples of implementation of traceability chains and certification mechanism

Figure C.1 illustrates examples of the implementation of traceability chains and the certification mechanism. In cases a) and b), a timing centre disseminates the timing information directly to the TSA. While the same timing centre provides the certifica-tion function in case a), the TAA provides certification to the TSA in case b).

In case c), the TAA provides both timing information and certification to the TSA. In case d), the TSA uses appropriate means to retrieve timing information, such as a cer-tified GNSS timing receiver, and the credibility of the information is assessed and cer-tified by the TAA. In this case, the TAA will need to have access to the UTC(k) provided by a timing centre to provide assurance in the traceability chain.

Timing centre Timing centre

Trusted third party

Trusted third party

Trusted third party

Trusted third party

Trusted third party

Trusted third party

Trusted third partyTiming centre Timing centre

TAA : Time assessment au-thority

TSA : Time stamp authority Dissemination Certification

cited from ITU-R TF.1876



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Annex D (informative) Required accuracy and frequency stability of

the reference clock

The reference clock used as a time source for the time auditing unit and for the time dissemination unit of the TAA clock should be accurate and stable.

In the case of the permitted margin of error of ±1 s, the required accuracy and fre-quency stability of the reference clock described in 7.2.4 are obtained as shown below.

a) The required accuracy of the reference clock is defined as ten times better than the accuracy of time distribution and the accuracy of time offset measurement in 7.2.4 b). Since the accuracy of time distribution and the accuracy of time offset meas-urement are stipulated to be both within ±50 ms in 7.4.4 c) and 7.3.4 c) , respec-tively, the required accuracy of the reference clock becomes ±5 ms or better.

b) The time error caused by the reference clock instability over the time offset meas-urement interval of the TSA clocks can be estimated to be τσy(τ), where τ is the time offset measurement interval and σy(τ)2 is the Allan-variance of the reference clock, which is a measure for frequency stability for τ. From the stipulation of 7.2.4 a) and by using the result of a) above, τσy(τ) becomes ±0.5 ms or less. In case of τ = 12 h, for example, σy(τ) is obtained to be 1.2 × 10－8 or better.

The concepts of accuracy and stability of a frequency source are shown in Figure D.1.

時間

周波数

安定度は高いが精度は低い

安定度は高く精度も高い

安定度は低いが精度は高い

安定度は低く精度も低い

fo

周波数周波数周波数

時間時間時間

Figure D.1 Accuracy and stability of a frequency source

Stable but not accurate

Not stable andnot accurate

Accurate but not stable

Stable and accurate

time time time time

freq. freq. freq. freq.



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_______________________________________________________________________________

Bibliography

[1] ANSI X9.95-2012 Trusted Time Stamp Management and Security [2] IETF RFC 5905 Network Time Protocol Version 4 : Protocol and Algorithms

Specification, June 2010 [3] ISO 19108 : 2002 Geographic information — Temporal schema [4] JIS X 5063-1 : 2005 Information technology — Security techniques — Time-

stamping services — Part 1 : Framework [5] JIS Z 8000-3 : 2014 Quantities and units — Part 3 : Space and time

NOTE The corresponding International Standard cites ISO 80000-3 : 2006 Quantities and units — Part 3 : Space and time.

[6] ISO 8601 : 2004 Data elements and interchange formats — Information inter-change — Representation of dates and times

[7] ISO/IEC 9594-8 : 2014 Information technology — Open Systems Interconnec-tion — The Directory : Public-key and attribute certificate frameworks, 6th edi-tion

[8] TS Z 0032 : 2012 International vocabulary of metrology — Basic and general concepts and associated terms (VIM)

NOTE The corresponding International Standard cites ISO/IEC GUIDE 99 : 2007 International vocabulary of metrology — Basic and general concepts and associated terms (VIM).

[9] ITU-R TF.536-2 : 2003 Time-scale notations [10] ITU-R TF.686-3 : 2013 Glossary and definitions of time and frequency terms [11] ITU-T Recommendation X.680 (11/2008) Information technology — Abstract

Syntax Notation One (ASN.1) : Specification of basic notation [12] Michael A. Lombardi, Traceability in Time and Frequency Metrology, Cal Lab :

The international Journal of Metrology, pp. 33-40, September-October 1999

[13] W. Lewandowski and C. Thomas, GPS time transfer, Proc. IEEE, vol. 79, No. 7, July 1991, pp. 991-1000

(References added for the purpose of JIS)

[14] Tadahiro Gotoh, et al., Evaluation of Time Transfer Precision with GPS All in View, IEEJ Transactions on Electronics, Information and Systems Vol. 125, No. 8, 2005

[15] Michito Imae, et al., Special Issue on Time and Frequency Standard, 4-3 Two Way Satellite Time and Frequency Transfer, Journal of the Communications Research Laboratory, Vo. 49, No. 1/2, 2003



17X 5094 : 2019


Ann

ex J

A (i

nfor

mat

ive)

C

ompa

riso

n ta

ble

betw

een

JIS

and

corr

espo

ndin

g In

tern

atio

nal S

tand

ard

JIS

X 50

94 :

2019

Tec

hnic

al re

quir

emen

ts fo

r TAA

to ce

rtify

UTC

-trac

eabi

lity

ISO

/IEC

180

14-4

: 20

15 I

nfor

mat

ion

tech

nolo

gy —

Sec

urity

tec

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— T

ime-

stam

ping

serv

ices —

Par

t 4 :

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of ti

me

sour

ces

(I)

Req

uire

men

ts in

JIS

(I

I) In

ter-

na

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anda

rd

num

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.


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