Bitten by the Y2K7 Bug

Was about to go to some Geocaching when it occurred to me that GPSr's use the time in order to know where the satellites are. If you're using your GPSr to keep you from getting lost in the wilderness, make sure you manually adjust for DST (assuming you're in a DST zone, and your GPSr doesn't know about the legislative changes). You might think you're headed back to the trail and end up heading into the mouth of a volcano.

See what happens when we rely too much on tools?


  1. junglejim16:03

    It's not quite like that.

    The GPS device will get a precise time signal from the satellites, each of which has an atomic clock on board. That's one reason why GPS can be used as a time source for NTP.

    I think the internal clock on the GPS is only used for getting a rough idea of where the satellites are going to be. If it's out then it might take a little longer to get a fix, that's all.

  2. @junglejim: Not only that, but the device SHOULD be internally set to UTC. The local timezone is only how the time is presented to the user. And you're correct - the internal quartz clock is only used to determine the approximate time so that it knows which satellite is which as it begins to receive the sequencing signal.