[time-nuts] Z3815 question

[Hui Zhang]

Hello Azelio:


 I browsed that webpage of TVB, I know Z3801A's EFC is 20bit, that is 2^20=1048576, I also review old archive of our mail-list, I saw Bob rbenward said his Z3801' EFC ramped up to the 1048560 so he got a EFC error. My 3801's EFC absolutely value now is +494788, about half value of full EFC range, it's not bad. I don't worry about my HP E-1938 Oscillator become to fail.
    I am looking for a new version Furuno GPS board or HP58534 (use GT-77 module) to replace my z3815 by acceptable price. But for now, even I don't replace it, my GPSDO also works well except data error.
    Thanks for your infomation.


Hui Zhang




At 2013-08-28 22:31:11,"Azelio Boriani" <azelio.boriani at screen.it> wrote:
>You can take a look here
>http://leapsecond.com/pages/z3801a-efc/
>for some insight about the EFC of the Z3801A that should be the same
>as the Z3815A.
>I think that the Furuno's problem with the 1024 week rollover is not
>properly a bug. I should say that the problem is with GPS designers
>that used only 10 bits to encode weeks. Anyway, it should be very
>interesting if the firmware of the GPS is readable, then the code can
>be patched to permanently add 1024 to the week number. Until now I
>have not found any reference about Furuno's firmware upload/dowload.
>
>On Wed, Aug 28, 2013 at 3:26 PM, Hui Zhang <ba6it at 163.com> wrote:
>> Hello Azelio:
>>     Thanks for your reply, about Z3815A auto survey, I found a command can fix it, it's:
>>    :GPS:POS:SURV:STAT:POW 0
>>    I don't know this command before, the Z3801 manual not include it (I haven't Z3815 manual, but they are kind of similar). When I used SatStat software, I found this command, it does worked.
>>   About strange years, my friend told me it's a Furuno GPS's bug, he gave me two url to explain it:
>>   http://www.furuno.com.cy/important-notice.html
>>   http://www.vk2hmc.net/blog/?p=727#comment-334
>>   I will review the old discussion that you talk about.
>>   I still not understand how HP define absolute EFC and relative EFC value, I will figure it out.
>>
>>
>> Best regards.
>>
>>
>> Hui Zhang
>>
>>
>>
>>
>>
>>
>>
>>
>> At 2013-08-28 18:14:53,"Azelio Boriani" <azelio.boriani at screen.it> wrote:
>>>The Z3815 doesn't store the surveyed location so at every power on it
>>>has to survey again. It is supposed you leave it on forever once
>>>installed.
>>>Strange date: the date reflects the fact that the Furuno GPSes have a
>>>1024 weeks rollover correction that was designed in 1993 and past 19
>>>years it reverts back. This "bug" was discussed here 2 weeks ago.
>>>
>>>On Wed, Aug 28, 2013 at 3:30 AM, Hui Zhang <ba6it at 163.com> wrote:
>>>> Sorry I forgot a qeustion about EFC, last night when I power on my Z3815A, it had a alarm message is "EFC limit", I use follow command to watch EFC value:
>>>>
>>>>
>>>> Sent: :DIAG:ROSC:EFC:ABS?
>>>> reply: +489118
>>>>
>>>>
>>>> Sent: :DIAG:ROSC:EFC:rel?
>>>> reply: -6.70809E+000
>>>>
>>>>
>>>> And then, I reboot the device, the alarm disappeared, the EFC value is:
>>>> Sent: :DIAG:ROSC:EFC:rel?
>>>> reply: +5.78499E-001
>>>>
>>>>
>>>> Sent: :DIAG:ROSC:EFC:ABS?
>>>> reply: +494788
>>>>
>>>> So, I want know what is normal EFC range of Z3815A?
>>>>
>>>>
>>>>
>>>>
>>>> Hui
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> At 2013-08-28 09:03:40,"Hui Zhang" <ba6it at 163.com> wrote:
>>>>>Dear All:
>>>>>     I just got a Z3815A GPSDOS, now it working well, but I have few questions:
>>>>>
>>>>>
>>>>>1, Why my Z3815A will do survey everytime at power on? Even its finished survey 100%.
>>>>>2, Why its date is 1994 Jun 11? But time is correct.
>>>>>3, What's type of antenna connector in back panel?
>>>>>
>>>>>
>>>>>Thanks!
>>>>>
>>>>>
>>>>>Hui
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