[time-nuts] Line Frequency

[Chris Albertson]

On Sun, Feb 9, 2014 at 4:27 PM, M. Simon <msimon6808 at yahoo.com> wrote:

> Tom,
>
> I was hoping for  1E-5 precision or better. My time stamping counter will
> have a 30 MHz clock (for convenience).


I think noise will not allow that level of accuracy with only one time
stamp per cycle.   I think you'd be better off making many samples per
cycle.  Taking 48,000 samples per second give 800 samples per cycle.  48K
is the "standard" sample rate for audio used with video.    Likely your
computer already has the means to sample two audio signals at 48K samples
per second.   It is not taxing on any modern computer or even for a smart
phone.

Doing this on my iMac is so trivial I don't bother to save the setup.  I
have an audio interface to samples 24 bits at 96K SPS.  I placed a 1 volt
peak to peak signal on it and then brought up a spectra display.  I can log
the spectra to a file.  This kind of software is available for free.

Chris Albertson
Redondo Beach, California