Recent TTN Upgrade

The recent upgrade to TTN on 18th July, included this comment;

“GPS time leap second calculations taking a new leap second into consideration for 6th of July 2022”

Has there been a GPS leap second added recently ?

The info I can find the last on were 31/12/2016, have not see info that one were needed to be add.

Me neither.

A live GPS is still reporting 18 leap seconds, which is the value set on 31/12/2016.

I have also read reports that the earth rotation are lately slightly faster.

There page were update last June 30, 2022

Speeds up and slows down - think 2020 it slowed slightly IIRC, and the earthquake that hit Fukashima shifted earths plates such that we sped up by (again IIRC) ~1.6millionth of a second! :wink: Didnt think GPS used leap seconds and was fixed to a reference & start point (similar to Unix or Broadcast TV EPOC’s?) but time standard adjusted by leap seconds to keep in sync, usually added end Jun or end Dec…nothing added end Dec 21, and as noted I think last was Dec 2016, think US military already indicating no plan to add one for Dec 22… ITU was considering dropping the whole idea of leap seconds due to logistics of (re)synching the worlds TCom infrastructure…though net effect of that would be we would be ~1hr adrift after 5000 years based on current drift, if I read correctly. Ah well yet another thing to worry about…

Me, too, the last I saw was that a leap second would not be added until ‘at least 31/12/2022’

The time used by the GPS network is fixed at some point in early 1980.

Whilst a lot of people assume a GPS puts out UTC, this is not fully correct. At first start up a GPS will put out GPS time + the number of leap seconds set in firmware and for a lot of GPSs this value is 16.

Every 12.5 mins a navigation message goes out from the GPS network that contains the correct value of leap seconds to give you UTC, when (and if) this is received then the time put out by the GPS is UTC.

Leap seconds have since the beginning of (GPS) time been added on 31st December or 30th June, so the mention of 6th July seemed a little odd.

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Do what Google and Amazon does, smear the second over a 24h period. (each have their own version of it) :slight_smile:

http://leapsecond.com/java/gpsclock.htm

The cryptic message in the changelog had another meaning - we considered 2022-07-06 04:59:42 +0000 UTC to be a leap second due to some technical debt. This caused the GPS timestamps outputted by the stack to always be off by 1 second.

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“On the 29 June 2022, the National Physical Laboratory in England recorded the shortest day in history at 1.59 milliseconds less than 24 hours”

Should we be worried ?

What did LIGO report?

No idea, does LIGO read the TTN Forum ?

I did used to go Walking\Mountaineering with a guy who was worldwide head of educational stuff in LEGO.

The Time travel guys - LIGO

The Laser Interferometer Gravitational-Wave Observatory (LIGO ) - Very interesting stuff.

Have not seen reports from them as to the total influence on our time there observation have had.

Depends! :thinking: does that mean we will live longer or is that now lost time?! :rofl:

:thinking: It says “Oh damn! there was a huge gravitational wave from two super massive black holes colliding some 3Bn years ago causing the earth to spin faster (hence shorter day)…and I must have missed it… my one chance to demonstrate my reason for existing…and I missed it…how could I?”, atleast I’m told that is the summary version of the report :wink: