[time-nuts] Portable Time Standard

[Joe Hobart]

Hello Petr,

Your accuracy results are impressive.  I have questions:

   What manufacture or brand DS3231 do you have?

   What do you use to communicate with the DS3231 and display time?

   How long has your DS3231 been running?

   Have you changed the crystal aging offset register(s) to compensate for
crystal aging?

Thank you,
Joe


On 2/15/2019 12:51 PM, Petr Titěra wrote:
> Hello,
> 
> sorry to reopen this old thread but it took me some time to measure. As
> I've said I have one RTC module sitting right on my desk in my room
> where temperatures can go anywhere between 3C and 20C.
> 
> Using naive method of comparison of time difference between system time
> and RTC module I get time difference only about 4.487869e-02 seconds in
> 22 days.
> 
> Petr Titera
> 
> Dne 14. 1. 2019 v 16:11 Joe Hobart napsal(a):
>> Hello Petr,
>>
>> I have not found a low power RTC chip that will keep 1 second a month with
>> changes in temperature.  This clock will be used to synchronize a portable
>> communications system.
>>
>> Thank you,
>> Joe
>>
>>
>> On 1/13/2019 2:23 PM, Petr Titěra wrote:
>>> I will probably sound dumb but did you consider cheap RTC chips? I have
>>> one based on DS3231 currently on my table and although its is specified
>>> to have precision +/-2PPM my seems to be in range about 0.5PPM right
>>> from package with possibility to do some corrections.
>>>
>>> Petr Titera
>>>
>>> Dne 11. 1. 2019 v 20:57 Joe Hobart napsal(a):
>>>> I need a relatively lightweight, self powered, portable clock accurate to 1
>>>> second per month.  Temperatures may range from 10 to 35 C; altitude from 1000 to
>>>> 7000 feet.  Although expensive, some of the marine quartz chronometers appear to
>>>> meet this requirement. ~0.3 PPM.
>>>>
>>>> Does anyone have any experience with these devices?
>>>>
>>>> If so, has anyone tried to detect the probably weak magnetic field generated by
>>>> the clock mechanism for time comparison purposes?
>>>>
>>>> Thanks,
>>>> Joe, W7LUX
>>>>
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>>>
>