[ntp:questions] Tobit LAN!Time DCF77 receiver not working

David Lord snews at lordynet.org
Wed Jan 6 10:47:34 UTC 2010


Rob wrote:
> Steve Kostecke <kostecke at ntp.org> wrote:
>> On 2009-12-25, Marc-Andre Alpers <m-a.alpers at web.de> wrote:
>>> Es schrieb Rob:
>>>
>>>> Be patient.  After a while things will stabilize and you can make another
>>>> judgement about the accuracy of your offset.
>>> I think that's good enough for me. Time1 0.0315
>>>
>>>     remote      refid   st t when poll reach  delay offset  jitter
>>> ===================================================================
>>> LOCAL(0)        .LOCL.  10 l   59   64  377   0.000  0.000   0.001
>>> *SHM(0)          .DCFa.   0 l   30   64  377   0.000 -0.296   0.194
>>> ntp1.sda.t-onli .PPS.    1 u   89  128  377  32.622 -0.116   2.408
>>> ntp1.sul.t-onli .PPS.    1 u   78  128  377  38.116 -0.156   4.512
>>> metasweb01.admi .HBGi.   1 u   80  128  377  39.068  0.323   0.559
>>> chronos.zedat.f .PPS.    1 u   84  128  377  40.878 -2.532  20.878
>>> ntp1.rrze.uni-e .DCFp.   1 u   76  128  377  36.008  0.583   0.930
>> Please keep in mind that this data is only an snapshot.
>>
>> Comparing peer offsets over a long period of time (e.g. at least a day)
>> will give you a better value for time1.
> 
> I think he said "that's good enough for me".
> Not everyone needs microsecond accuracy.  Or even millisecond.
> 
> And if you do, it is not a good idea to use DCF77 anyway.

I'm about 1000km away and propagation effects give me a
complete loss of signal twice a day on most days
depending on weather conditions etc so even ms accuracy
is difficult to maintain.

I'm pretty sure us accuracy is available at closer range
since it is possible to sync to exact cycle of carrier
with period of around 13us, ie to within a fraction of
that so 1us shouldn't be a problem.

The TDF transmission might be usable from here as a lot
closer and at higher frequency than DCF77 and provides
similar capability.

David




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