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  1. #11
    Member memento_mori's Avatar
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    Re: Question: GPS time synch 10 seconds fast GPW-1000

    Wikipedia:

    ++++++++++

    While most clocks derive their time from Coordinated Universal Time (UTC), the atomic clocks on the satellites are set to GPS time (GPST; see the page of United States Naval Observatory). The difference is that GPS time is not corrected to match the rotation of the Earth, so it does not contain leap seconds or other corrections that are periodically added to UTC. GPS time was set to match UTC in 1980, but has since diverged. The lack of corrections means that GPS time remains at a constant offset with International Atomic Time (TAI) (TAI − GPS = 19 seconds). Periodic corrections are performed to the on-board clocks to keep them synchronized with ground clocks.

    +++++++++

    It is of 19 seconds, not 10

    GPS time is not a reference for time adjustment, it is for navigation purposes!
    Last edited by memento_mori; 1 Week Ago at 12:09.

  2. #12
    Member will70's Avatar
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    Re: Question: GPS time synch 10 seconds fast GPW-1000

    Interestingly enough it is 645 am in Nova Scotia and I just performed another GPS time sync and this time the watch ended up being spot on with time.is network time.

    Don’t know what happened last night.




    Sent from my iPhone using Tapatalk

  3. #13
    Member WES51's Avatar
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    Re: Question: GPS time synch 10 seconds fast GPW-1000

    Guys, this GPS offset behavior is NEW here on the F17, at least to me.

    Before that, when ever we were discussing MB6 vs. GPS vs. Bluetooth, no one has ever mentioned that there was such a massive discrepancy of GPS time. GPS was always presented here as an accurate world wide working alternative to MB6, with the only downside of the GPS signal missing DST.

    I have to say I find any inaccuracies unacceptable, let alone 10 or 19 seconds. So I took a note to myself for the future NOT to pursue any GPS sync watch, as such level of inaccuracy just won't work for me.

    Long live MB6!
    Last edited by WES51; 1 Week Ago at 16:42.

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  5. #14
    Member will70's Avatar
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    Re: Question: GPS time synch 10 seconds fast GPW-1000

    Quote Originally Posted by WES51 View Post
    Guys, this GPS offset behavior is NEW here on the F17, at least to me.

    Before that, when ever we were discussing MB6 vs. GPS vs. Bluetooth, no one has ever mentioned that there was such a massive discrepancy of GPS time. GPS was always presented here as an accurate world wide working alternative to MB6, with the only downside of the GPS signal missing DST.

    I have to say I find any inaccuracies unacceptable, let alone 10 or 19 seconds. So I took a note to myself for the future NOT to pursue any GPS sync watch, as such level of inaccuracy just won't work for me.

    Long live MB6!

    Hi Wes

    In all fairness I just got the watch yesterday and it seemed to me that the sync was 10 seconds ahead of network time however as a caveat it was dark and foggy and I was inside first time and then on my deck second time.

    This morning it synced bang on.

    I just did another gps sync at 11:20am to double check and it again was bang on with no discrepancies.

    I wouldn’t discount the technology myself at this point. Seems to be working fine.


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    WES51 and Time4Playnow like this.

  6. #15
    Member WES51's Avatar
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    Re: Question: GPS time synch 10 seconds fast GPW-1000

    Quote Originally Posted by will70 View Post
    I wouldn’t discount the technology myself at this point. Seems to be working fine.
    Well, that is what I always thought, until I stumbled upon this thread.

    I really wish that this is all one big misunderstanding and GPS is always spot on accurate after all.

  7. #16
    Member memento_mori's Avatar
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    Re: Question: GPS time synch 10 seconds fast GPW-1000

    Quote Originally Posted by WES51 View Post
    Well, that is what I always thought, until I stumbled upon this thread.

    I really wish that this is all one big misunderstanding and GPS is always spot on accurate after all.
    What? Have you never had any interest how the navigation on your smartphone works? Or the time synchronization on a gps watch? Really?

    A gps watch reads the time signal of the gps signal and corrects it with 20 seconds — that’s all and everywhere to read.

    GPS time is absolute correct as a navigation tool, not as a time signal.

    Second, the satellites are far, far away, which brings a deviation - just like the radio signal from the time transmitter - the signals take time from the transmitter to the receiver.

    The right time is UTC and this is an international convention. There is no such thing as a right time, there is only a deviation from UTC, that's all.

    Furthermore, the GPS satellites are in zero gravity, which means that the atomic clocks go a little faster on board than on earth, so they have to be corrected with a reference atomic clock on earth (general relativity theory)
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  8. #17
    Member WES51's Avatar
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    Re: Question: GPS time synch 10 seconds fast GPW-1000

    Quote Originally Posted by memento_mori View Post
    What? Have you never had any interest how the navigation on your smartphone works? Or the time synchronization on a gps watch? Really?
    No, please forgive my ignorance, but I was completely unaware of this. Moreover like I have mentioned, there have been countless discussions about MB6, GPS and Bluetooth and none of them has mentioned anything about GPS being not spot on. I recall quite the contrary.

    I didn't mean to bash GPS watches, I just could not hide my disappointment that has poured out of me. To better understand my background, one of my MB6 watches syncs to about 0.1-0.2 seconds off spot on and that already drives me nuts.

  9. #18
    Member Time4Playnow's Avatar
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    Re: Question: GPS time synch 10 seconds fast GPW-1000

    Quote Originally Posted by will70 View Post
    Hi Wes

    In all fairness I just got the watch yesterday and it seemed to me that the sync was 10 seconds ahead of network time however as a caveat it was dark and foggy and I was inside first time and then on my deck second time.

    This morning it synced bang on.

    I just did another gps sync at 11:20am to double check and it again was bang on with no discrepancies.

    I wouldn’t discount the technology myself at this point. Seems to be working fine.

    Sent from my iPhone using Tapatalk

    Just my opinion, but I suspect you did not actually sync via GPS when you first thought you did. (Especially if inside; it doesn't work unless the watch has a direct view of the sky) Might the watch have synced via MB6? Or maybe it did not actually sync when you thought it did?

    I think some ppl have incorrect views of GPS time syncing. Do you really think Casio would provide GPS sync capability on their watches if it could be 10 or 20 seconds off????! No.

    I have had a large number of Casio GPS watches. Mostly GPW-1000s, but also an MT-G, two GPS Rangers, and currently an MR-G. They have always been spot-on with the correct time after a sync. Without fail. If there are in fact discrepancies in a GPS satellite's time reference signal, clearly it is compensating for that somehow. This is not hypothetical. It's based on my own experience.

    Casio GPS time syncs work. Don't believe the naysayers.
    Last edited by Time4Playnow; 1 Week Ago at 21:38.
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  10. #19
    Member memento_mori's Avatar
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    Re: Question: GPS time synch 10 seconds fast GPW-1000

    Quote Originally Posted by WES51 View Post
    To better understand my background, one of my MB6 watches syncs to about 0.1-0.2 seconds off spot on and that already drives me nuts.
    The radio wave travels, this needs time, more the processor in the watch needs time. With 0.2 seconds it is very good.

    And think of the equitation of time! Earth itself is in between +16 and -14 minutes (!) of the correct time over a year — so 0.2 seconds are not really a problem


    https://http://en.wikipedia.org/wiki/Equation_of_time

  11. #20
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    Re: Question: GPS time synch 10 seconds fast GPW-1000

    Quote Originally Posted by Time4Playnow View Post
    Just my opinion, but I suspect you did not actually sync via GPS when you first thought you did. (Especially if inside; it doesn't work unless the watch has a direct view of the sky) Might the watch have synced via MB6? Or maybe it did not actually sync when you thought it did?

    I think some ppl have incorrect views of GPS time syncing. Do you really think Casio would provide GPS sync capability on their watches if it could be 10 or 20 seconds off????! No.

    I have had a large number of Casio GPS watches. Mostly GPW-1000s, but also an MT-G, two GPS Rangers, and currently an MR-G. They have always been spot-on with the correct time after a sync. Without fail. If there are in fact discrepancies in a GPS satellite's time reference signal, clearly it is compensating for that somehow. This is not hypothetical. It's based on my own experience.

    Casio GPS time syncs work. Don't believe the naysayers.

    Thanks for the info.

    It is all quite interesting isn’t it. The way we humans measure time and in our arrogance we still have to add here and subtract there and makeup here and regulate there.

    It makes me contemplate on math itself being an imperfect language to describe certain circumstances.


    Sent from my iPhone using Tapatalk
    Time4Playnow likes this.

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