[time-nuts] Warped back to 1993

Azelio Boriani azelio.boriani at screen.it
Sun Aug 11 11:29:53 UTC 2013


OK, good, found the bug. Now, iwe wish it were possible to download
the firmware, make the correction and then upload...

On Sun, Aug 11, 2013 at 1:14 PM, Magnus Danielson
<magnus at rubidium.dyndns.org> wrote:
> On 08/11/2013 05:18 AM, Mark C. Stephens wrote:
>> Okay this is what worked for me:
>>
>> 1. Removed power and antenna.
>> 2. apply power with no antenna.
>> 3. send :GPS:INIT:DATE 2007,08,11
>> 4. plug antenna back in.
>>
>> For some reason if I used the correct date, the Z3815A warped back to 1993.
>>
>> But I am curious why did this happen today?
> GPS weeks begin on sundays. Today is first day of week 1753:
>
> http://csrc.ucsd.edu/scripts/convertDate.cgi?time=2013+08+11
>
> Going back 1024 days gives you week 729 day 0, which occurs on 1993 12 26:
> http://csrc.ucsd.edu/scripts/convertDate.cgi?time=1993+12+26
>
> A simple way to compensate for the lack of bits is to assume wrapping
> occurs, so week numbers lower than som value actually lacks 1024 weeks.
> A trivial code like this fixes this:
>
> if (week < 729)
>     week += 1024;
>
> Brilliant until you reach week 1753.
>
> I've seen this happen at 500 and 512.
>
> Cheers,
> Magnus
>
>>
>>
>> --marki
>>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Mark C. Stephens
>> Sent: Sunday, 11 August 2013 1:06 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] Warped back to 1993
>>
>> Hal, I can't get it to take, I keep getting E-350 and the time does not change.
>> Did you unplug the antenna or anything while you changed date?
>>
>>
>>
>>
>>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Hal Murray
>> Sent: Sunday, 11 August 2013 12:54 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] Warped back to 1993
>>
>>
>> marks at non-stop.com.au said:
>>> A Z3805A, a Z3815A and 58534A integrated timing antenna all think it's
>>> 26 Dec 1993.
>>> What happened?! _______________________________________________
>> Is that off by 1024 weeks?  (Looks close, but I haven't checked the details.)
>>
>> There is a week field in the GPS data stream.  It's only 10 bits.
>>
>> I had that problem on a Z3801A.  It did the right thing after I told it the date.
>>   :GPS:INIT:DATE 2011,12,26
>>
>>
>>
>
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