[time-nuts] NAVSTAR proteus GPS time and frequency unit
magnus at rubidium.dyndns.org
Sun Nov 8 21:06:38 EST 2015
On 11/09/2015 01:07 AM, paul swed wrote:
> Because the roll over is a pain.
> Thats good engineering if they checked that far.
> What happens if you have a receiver that doesn't handle it correctly is you
> do not tend to get satellite lock because the dates all wrong.
No. The GPS internal date-format avoids this issue altogether, it's the
conversion from the GPS date gears to "user dates" that gets confused
due to lack of additional bits for GPS weeks, but the GPS receiver can
keep operate even if the GPS weeks wrap, with very little software
concern. So, after the GPS week wrapping, wherever it occurs for a
receiver, only means that the published user date becomes wrong, not the
GPS system internal date, the receiver keeps working through it,
whatever it is.
> You cheat this "The pain part" by figuring out what the date should have
> been by subtracting 1024 weeks. Seems easy right. Nope.
I've only seen receivers fail in their date conversion, and in exactly
> That works for the old austron. But as I say serious thinking. There are
> some online tools that help. But it all gets old very fast.
> On Sun, Nov 8, 2015 at 4:01 PM, Rob Sherwood. <rob at nc0b.com> wrote:
>> Why is this an issue?
>> Sent from my iPad
>>> On Nov 8, 2015, at 1:00 PM, "Brendan Giles" <brendan_giles at hotmail.com>
>>> I was the project manager who was in charge of the NAVSTAR proteus GPS
>> time and frequency unit.The two GPS rollover dates 1999/2018 were tested in
>> product test plan. Also various dates were checked upto 2037 for the PC
>> output message.
>>> Brendan Giles
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