[time-nuts] Warped back to 1993

[Bob Camp]

Hi

One point worth mentioning - the device will still be quite happy acting as a GPSDO. It simply will not be of much use for NTP (or any other date dependent system).

Bob

On Aug 11, 2013, at 7:44 AM, Mark C. Stephens <marks at non-stop.com.au> wrote:

> Azelio, is your Furuno playing up?
> 
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Azelio Boriani
> Sent: Sunday, 11 August 2013 9:30 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Warped back to 1993
> 
> 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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