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From: Mith on 16 Jun 2010 17:42
I must measure the grid frequency (50Hz here).

I don't have any zero crossing detector on board. But I can sample the
voltage. I don't want to sample too often.

But the voltage is going to be noisy and have disturbances so I think i must
filter my samples before trying to analyze the frequency.

Any tip?


From: Tim Wescott on 16 Jun 2010 18:19
On 06/16/2010 02:42 PM, Mith wrote:
> I must measure the grid frequency (50Hz here).
>
> I don't have any zero crossing detector on board. But I can sample the
> voltage. I don't want to sample too often.
>
> But the voltage is going to be noisy and have disturbances so I think i must
> filter my samples before trying to analyze the frequency.

How often is reasonable, how accurately can you sample the voltage, how
accurate must your measurement be, and how close to 50Hz is your grid
frequeny (i.e. is it always grid frequency, or might you have occasion
to measure the output of a 50Hz synchronous generator)?

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
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