GPS Epoch Issue

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  • 16 Feb 2019 14:44
    Reply # 7168326 on 7167569
    Anonymous wrote:

    My deal little Garmin 76 that was given to me in 2001 and works perfectly, will now be obsolete and something else to go into landfill.  And every time I turned it one, it reminded me of my old friend, now long deceased, who gave it to me.  There are times that the 21st century fills me with despair.  I still have my sextant, of course, but liked my GPS to see how miles I'd sailed.  I also found it useful for 'will I get there before sunset?' calculations.  I am disinclined to shell out for another one.

    Phones and GPS.  I must have this wrong, but on occasion I've used the GPS on my phone, via Maps, and when it's lost its phone signal, it also loses its map.  Could one trust it as an alternative to GPS offshore?




    Bonjour

    The change should not affect the main GPS function (providing the position on a WGS84 reference) but a side function that provides the UTC time reference. The GPS time is not exactly the same as the UTC (there are few seconds shift) and, for size of the signal issue, the date data is shortened. The GPS signal gives only a week information. If the receptor GPS program is "economic" the decoding from the GPS "date" reference to the UTC date reference could be affected by the present change. The impact would be that the date could be strange (something like 20 years ago) but the time and position would remain good.

    So, please, keep your loved GPS for manny years.

    Eric

    Last modified: 17 Feb 2019 18:07 | Anonymous member
  • 15 Feb 2019 22:29
    Reply # 7167778 on 7167569
    Anonymous wrote:

    My deal little Garmin 76 that was given to me in 2001 and works perfectly, will now be obsolete and something else to go into landfill.  And every time I turned it one, it reminded me of my old friend, now long deceased, who gave it to me.  There are times that the 21st century fills me with despair.  I still have my sextant, of course, but liked my GPS to see how miles I'd sailed.  I also found it useful for 'will I get there before sunset?' calculations.  I am disinclined to shell out for another one.

    Don't give up on it until you've asked https://support.garmin.com/en-NZ/ about epoch rollover.

    Phones and GPS.  I must have this wrong, but on occasion I've used the GPS on my phone, via Maps, and when it's lost its phone signal, it also loses its map.  Could one trust it as an alternative to GPS offshore?

    You need a marine chart app. Try going to Google Play and looking for Aqua Map, free to download the app, then pay for the charts. On my iPad (in iOS) I could get an everlasting set of LINZ charts in this app for £9.99 or a 1 year subscription for £4.49 so I guess it's the same in Android.




  • 15 Feb 2019 21:35
    Reply # 7167676 on 7167569
     Annie Hill wrote:

    Phones and GPS.  I must have this wrong, but on occasion I've used the GPS on my phone, via Maps, and when it's lost its phone signal, it also loses its map.  Could one trust it as an alternative to GPS offshore?

    You could try OsmAnd (free I think) which continues to work with no wifi/phone service.

    And here I was wondering what was going to happen in 2038 (32bit clock rollover) ... I still hope to be around 20 years from now. I sort of thought 64 bit everything would get rid of that, but the standard calls still return a 32 bit value. :P (a 65bit clock is good for (I think) 5000 years or so.

  • 15 Feb 2019 20:50
    Reply # 7167569 on 7163048

    My deal little Garmin 76 that was given to me in 2001 and works perfectly, will now be obsolete and something else to go into landfill.  And every time I turned it one, it reminded me of my old friend, now long deceased, who gave it to me.  There are times that the 21st century fills me with despair.  I still have my sextant, of course, but liked my GPS to see how miles I'd sailed.  I also found it useful for 'will I get there before sunset?' calculations.  I am disinclined to shell out for another one.

    Phones and GPS.  I must have this wrong, but on occasion I've used the GPS on my phone, via Maps, and when it's lost its phone signal, it also loses its map.  Could one trust it as an alternative to GPS offshore?



  • 15 Feb 2019 10:18
    Reply # 7166731 on 7163048

    Never mind - there's a GPS in the phone on which I'm writing this. If anyone is seriously concerned,  I have a Freiberger Sextant on eBay, bidding starts at £200.

  • 15 Feb 2019 08:45
    Reply # 7166630 on 7163048

    Thanks for bringing this to our attention, Roger. As far as I understand it (which isn't very far), equipment manufactured after 2010 should be OK.

    But still, after April 6th and before I go cruising for the summer, I'll check my Furuno GP31 and my iPad, in case I've suddenly become a Prairie Schooner.

  • 13 Feb 2019 20:55
    Message # 7163048

    Hi Folks, 

    I'm posting this as it has the potential to affect members.

    Reading one of my technical geek sites I came across this this URL https://www.theregister.co.uk/2019/02/12/current_gps_epoch_ends  which explains the issue.

    I can't summarise it better than the article, so I'll re-produce this snippet.

    Older satnavs and such devices won't be able to use America's Global Positioning System properly after April 6 unless they've been suitably updated or designed to handle a looming epoch rollover.

    Think of it as the Millennium Bug for older GPS systems.

    I've attached the PDF from US Homeland Security.

    Roger

    1 file
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