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GPS Week Number Rollover....and GLONASS!

Discussion in 'Fred's House of Pancakes' started by ETC(SS), Mar 11, 2019.

  1. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    Fun fact: GPS uses 10 bits to store the week. That means it runs out... oh heck – April 6, 2019 • The Register

    What was old is new again! :)

    Back about a million years ago (as measured by millennials) I worked for a company that was eventually swallowed up by SAIC.
    We made big coin back then in an intense effort to thwart the end of human life on Earth by certifying dot.gov systems to be free of the Y2K bug.
    One must remember that this was back in an ancient time when bipeds struggled to feed, shelter and clothe themselves without iphones, and only birders listened to tweets.
    Since I didn't like the drama and tumult of working as a tick feeding on the backside of DOD at that time, I transitioned into a layoff-proof industry:
    Telecommunications.

    ...Oops. :eek:
    One of my very first overtime checks in fact, came from sitting in a central office as 1999 became 2000, since I was junior enough to be 'voluntold' to sit and watch the clocks switch from 23:59:59 to 00:00:00.

    Another Fun Fact: Earlier that same day, Russian President Yeltsin announced that he would be resigning early in the belief that “Russia should enter the new millennium with new politicians, new faces, new people, who are intelligent, strong and energetic, while we, those who have been in power for many years, must leave."
    An obscure Incumbent Prime Minister Vladimir Vladimirovich Putin was then elevated to that post, an office that he would be elected to later by more than 100-percent. ;)

    Sadly, my only personal devices that support GLONASS are my fitness tracker and a recently re-retired iPhone 5S.... :(

    What is GLONASS And How It Is Different From GPS
     
    #1 ETC(SS), Mar 11, 2019
    Last edited: Mar 11, 2019
  2. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    I stopped buying devices that relied on GPS alone. I find it incredibly annoying that it's run by the DoD and they randomly interfere with it for "tests".

    My current phone uses a BCM47755 inside. It's a simultaneous dual frequency chip (L1 and L5) that I can connect to:
    • GPS L1 C/A
    • GLONASS L1
    • BeiDou (BDS) B1
    • QZSS L1
    • Galileo (GAL) E1
    • GPS L5
    • Galileo E5a
    • QZSS L5
    Covered and works perfectly all across the globe. And when the US decides to disrupt GPS for a few days, I still get marginal enough coverage from the others that it doesn't matter.

    It technically can do tenths of a meter accuracy without relying on the clearance-required GPS signals. Just the open signals on the other sats. However in practice, the software in my phone uses only the main bands but that still gives me about 1m accuracy like GPS. With the dual frequency though I get the same accuracy while walking through skyscrapers in New York City as I do out in a field on a remote atoll in the South Pacific.
     
    #2 2k1Toaster, Mar 11, 2019
  3. bisco

    bisco cookie crumbler

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    Much ado about nothing?
     
    #3 bisco, Mar 11, 2019
  4. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    Not even that.
    Not much ado about nothing much......

    ....maybe. ;)


    If I'm not mistaken the week number rollover problem was a thing with Block I and maybe early Block II birds, and not even much of a problem at that.
    It's easy to forget that the GPS system is over 40 years old, and we're trying to get Block III birds in orbit - a military expenditure that a future administration may or may not cut at will.

    As mentioned above, multi-band GNSS receivers have gone from zero to medium-significant in just a few years, and even now it's more likely than not that you have GLONASS and perhaps even Gallileo capability (Beidou is regional IIRC.)
    GLONASS is always subject to "control segment issues" but it's also wise to remember that even the newer Galileo systems are subject to their little interruptions as well, albeit from more of a committee or a technological thing.
    Brussels has to green light "planned" outages and they've pretty much sorted out their clock problems.

    It will be fun to watch how L4 and L5 autonomous vehicles treat this newfound wealth of navigation inputs.....
     
    #4 ETC(SS), Mar 11, 2019
  5. bisco

    bisco cookie crumbler

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    I’m thinking Toyota gps can only improve...
     
    #5 bisco, Mar 11, 2019
  6. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    The Toyota GPS is already very good. The external mounted antenna is rarely blocked and it is completely compensated by wheel speed and magnetic inputs for directionality. That's why you can still see the map update while driving through a long tunnel when the GPS signals are long gone. If you're talking about the UI for the navigation, that's not "GPS". GPS is one of the input to the UI to draw the pretty arrow.
     
    #6 2k1Toaster, Mar 11, 2019
    Trollbait likes this.
  7. ChapmanF

    ChapmanF Senior Member

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    I was just sitting in a 2009 last night and noticed (for the first time ever) the MFD has a 'calendar' function! You can even enter reminders. But it's convinced the date is in May 2005.

    So I looked in my 2010 and found it, too, has a calendar function, de-featured so now I can't select a day and add reminders or anything, it's just a static calendar. But my 2010 still has the date right (even though it was made long before the 2019 rollover).

    I saw an article from Raymarine that could shed light. Their receivers come with the week of their manufacture baked in. So their dates don't roll over when the week number rolls to zero, but when it rolls past the manufacture week again. So my 2010 might make it as far as 2029 before the calendar gets wrong.

    On the other hand, the nav unit could have been manufactured a lot earlier than the car ... witness the 2009 unit thinking it's 2005. (That 2009 happens to be a salvage rebuild, so the actual vintage of the MFD could be different.)

    The 2009 is still able to locate satellites and give accurate lat/lon, despite having the date wrong.
     
    #7 ChapmanF, Nov 10, 2024 at 11:55 AM
  8. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    GNSS is still GNSS.
    That means that you can derive your 3-D position. (lat/lon/alt) with the your receiver - because: Physics.

    ALSO!
    You can solve for the 4th-D, because: Physics.
    You just need to use RI (Real Intelligence) instead if AI.
     
    #8 ETC(SS), Nov 11, 2024 at 5:15 AM
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