[time-nuts] Logging the grid frequency....

[Daniel Mendes]

Ok, it´s a relative measurement... now I understand your data. Thank you.

Daniel


Em 28/02/2013 20:03, Tom Van Baak (lab) escreveu:
> Yes, correct, sometimes the power line goes faster than 60 Hz in which case the zero-crossings occur before you "expect them"; so time error can be negative, on average, as often as it is positive.
>
> You cannot design a PLL that always expects phase error to be unidirectional.
>
> The data I provided is time error relative to an ideal 60 Hz; this data can be both positive and negative; and both gaining and losing, as well as both accelerating and decelerating. Welcome to the interesting world of time & frequency, even at 60 Hz.
>
> /tvb (iPhone4)
>
> On Feb 28, 2013, at 10:42 AM, Daniel Mendes <dmendesf at gmail.com> wrote:
>
>> Em 28/02/2013 13:37, Tom Van Baak escreveu:
>>> Daniel,
>>>
>>> I've placed two log files for you under http://leapsecond.com/pages/mains/
>>>
>>> log1932.dat.gz -- timing of every 60 Hz zero-crossing (1.296 million samples)
>>> log97312.dat.gz -- timing of every 60th zero-crossing (21.6 thousand samples)
>>>
>>> Each represents 6 hours of collection time. Units are seconds (elapsed time), resolution is 100 ns, granularity is 400 ns. This data was collected with a picPET (http://leapsecond.com/pic) using an accurate 10 MHz reference.
>> This isn´t very clear to me. First few lines say:
>>
>> 0.0000000
>>
>> -0.0000029
>>
>> -0.0000071
>>
>> -0.0000064
>>
>> 0.0000027
>>
>> -0.0000099
>>
>> -0.0000176
>>
>>
>> Time went backwards?
>>
>>
>> Daniel
>>
>>
>>
>>
>>
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