[time-nuts] 58503A date code problem

[Dave Martindale]

Interesting.  It was May 22 this year when I first noticed that my
Garmin 45XL was reporting a date in 1994, exactly 1024 weeks early.
That's also consistent with Garmin having used 768 weeks as their
"fence" for a GPS week being in the past instead of the future.

It's really the same as the International Date Line, picking an
arbitrary line that advances and retards the apparent time as you
cross it.  But the delta-time for the GPS week rollover is nearly 10
years, instead of 24 hours.

- Dave

On Sat, Jun 21, 2014 at 3:44 PM, Tom Van Baak <tvb at leapsecond.com> wrote:
> Hi Daniel,
>
> What you have is a 58503A, the GPS time/frequency receiver (the 58530A is a GPS bandpass filter).
>
> Note that today is MJD 56829. Exactly 1024 weeks (7168 days) ago was November 4, 1994. So this looks like a typical GPSDO week number rollover issue. It shouldn't affect the time or the 1PPS or the 10 MHz. One thing to try is manually setting the date using a SCPI command.
>
> You can check www.realhamradio.com/GPS_websites_list.htm to see if anyone else has seen this on their 58503A or Z3801A receivers.
>
> Did you notice it happened just today, or did it start happening maybe a few weeks ago?
>
> I ask because recently we passed the 3/4 mark in the current 1024-week (19.6 year) GPS cycle. Specifically, on 2014-05-04 it was 768 weeks since the last rollover (1999-08-15) and 256 weeks before the next rollover (2019-03-31).
>
> /tvb
>
> ----- Original Message -----
> From: "Daniel Burch" <daniel.burch at ieee.org>
> To: <time-nuts at febo.com>
> Sent: Saturday, June 21, 2014 10:06 AM
> Subject: [time-nuts] 58503A date code problem
>
>
>> Hi All,
>>
>> I have a HP/Symm 58530A that has the correct time, but date keeps
>> defaulting to 1994, Nov, 4 after GPS Lock.  The pre-lock is 1996, so I do
>> see a change when it locks, just to the wrong date.....time is exactly
>> correct and tracks.
>>
>> Any ideas?
>>
>> Thanks!
>>
>> db
>
>
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