[time-nuts] Warped back to 1993

[Magnus Danielson]

If Furuno can supply the FW to update with, we would be more than happy.

A slight alteration of the code would suffice...

if (week < 729)
    week += 2048;
else
    week += 1024;

Which would keep them floating for another 1024 weeks. If they then let
us know where the two constats is located so we could modify it again
ourselves we be very happy.

Cheers,
Magnus

On 08/11/2013 01:29 PM, Azelio Boriani wrote:
> 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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