Japanese Activities and Views on the Agenda Item 1.14 Tsukasa Iwama National Institute of Information and Communications Technology (NICT) JAPAN

CPM text Method A ( continuous time-scale ) – A1 ( name UTC ), A2 ( new name) Method B ( cont. time-scale & UTC on an Equal basis) Method C ( keep UTC, additional cont. time-scale) – C1 (TAI as the cont. time-scale), C2 ( new cont. time-scale)

About Method B Retain UTC as currently defined and introduce a continuous reference atomic time-scale based on TAI with an offset to be broadcasted on an equal basis. Japanese Views – In the case of Method B, it means that two time scales will be disseminated in parallel. – Whenever you act based on time, you always need to check the time-scale and need to convert the time- scale if necessary. – Dissemination of two time scales becomes a cause of significant confusion in social life.

About Method C (1) No change in definition of UTC as specified in Recommendation ITU R TF.460-6, which will remain the only time-scale which is broadcast in order to avoid any confusion. Japanese View – In this part, we agree with the view that only one time-scale should be broadcast in order to avoid any confusion. – It needs to be discussed later whether this “one time-scale” shall be “UTC”.

About Method C (2) Under this method, the recommendation ITU-R TF would be amended to make clear that use of TAI is an acceptable alternative for those requiring a continuous time-scale and that it can be derived from UTC using a difference figure, which is also being broadcasted. Japanese View – This part includes the same problem as Method B, it becomes a cause of significant confusion.

Requirement for the time-scale We consider that the international standard reference time-scale should be only one. Which is better traditional UTC or Continuous Time-scale?

Japanese Contributions to AI Input a questionnaire of UTC (7A/31) /31leap second insertion 2007Input a questionnaire of leap second (7A/49) /31leap second insertion /30leap second insertion 2012 Input report of leap second incidents (7A/11)

Summary of the CRL questionnaire the future of UTC (7A/31 :2002) - Do you think the determination method of UTC should be changed? The questionnaire was circulated at the end of 2001 to major Japanese organizations, companies and to time and frequency users. In total we received 80 replies. *CRL (presently known as NICT)

Japanese Contributions about AI Input a questionnaire of UTC (7A/31) /31leap second insertion 2007Input a questionnaire of leap second (7A/49) /31leap second insertion /30leap second insertion 2012 Input report of leap second incidents (7A/11)

Questionnaire ON “possible future change to Coordinated Universal Time (UTC)” in JAPAN (7A/49 :2007) Field Effect of past leap second adjustment Effect of future change to UTC Agree or disagree with future change Broadcasting carriers None (probably Manual adjustment) None (Find the merit in disappearing in an irregular leap second adjustment) Agree Telecommunications carriers None (probably Manual adjustment) None (Find the merit in disappearing in an irregular leap second adjustment) Agree Time stamp authorities Operation stoppedNoneAgree GPS receiver manufacturers None (Problem with bit length of the navigation message of the GPS in the future ) None in near future (New adjustment method may involve the possibility of significant problems) Both agree and disagree Geographical Survey Institute None (Manual adjustment) Need to adopt some changes to the control programs - Satellite launching enterprise Made some changes to the control programs Need to adopt some changes to the control programs -

Japanese Contributions about AI Input a questionnaire of UTC (7A/31) /31leap second insertion 2007Input a questionnaire of leap second (7A/49) /31leap second insertion /30leap second insertion 2012 Input report of leap second incidents (7A/11)

Incident of the leap second adjustment in Japan (7A/11 : 2012) (1) 1.Many faults were occurred universally on the process in the application of Linux such as MySQL, Hadoop, Cassandra and so on. （ The Linux trouble was also occurred in 2009) – In Japan, the system delay caused by the same faults were also officially reported by well-known Social Network System (SNS), Groupware, and Internet Service Provider (ISP). – Many other faults on applications have been reported.

Incident of the leap second adjustment in Japan (7A/11 : 2012) (2) 2.In Time-stamping services, all the Time- Stamping Authorities were suspended providing the services to the users beforehand to prevent from giving the wrong time information. – The cessation of services lasted about 2hours on the average. – In addition, based on the last experience (2009), they tried to shorten suspension period, and they found that this was impossible from a safe viewpoint.

A Positive leap second will be introduced at the end of June In Japan, it will be at 9:00 on 7/1 Wednesday. Incident of the leap second adjustment in Japan (7A/11 : 2012) (3) 3.Even though the leap second adjustment was implemented on Sunday this time, various kinds of obstacles or system suspensions occurred. In the future, the leap second adjustment carried out on weekdays may cause widely spread confusions throughout the country at 9 o’clock (JST) of the starting time for the general business.

Disadvantage of Cont. time-scale The offset between UT1 and UTC will be higher than the current limit of 0.9 s. – Most of network systems and applications will be work well. But some applications such as earth stations of the satellite non-GSO systems, radio astronomy stations will be affected. – It will be necessary to modify these special systems. A civil time scale would deviate from UT1 after introduction of the continuous time scale. – UT1 - UTC will be on the order of 1 min in the first hundred years.

Which is better? Traditional UTC – Number of Incidents of internet services and applications will increase in every time. – In Asia-Pacific region, leap second adjustment occurs during working hours. Continuous time-scale – Most of network system and applications will work well. But some systems need system modifications. – A civil time-scale would deviate from UT1. But the apparent solar time can differ already by some  16 minutes from the mean solar time. Continuous time-scale is better than traditional UTC.

Japanese Views Japan supports to introduce the new continuous reference time-scale by stopping the insertion of leap seconds in UTC. Japan supports the name of UTC to be retained after the introduction of the new continuous reference time-scale.

THANK YOU FOR YOUR ATTENTION