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

[Dan Kemppainen]

On 2/28/2013 11:37 AM, time-nuts-request at febo.com wrote:
> About the difficulty of measuring every cycle with a conventional
> counter... thanks for that info, seems that i?ll have to make my own
> measurement hardware. I liked the idea of a time stamping counter....
> it?s very doable in a FPGA:)

At work we have a similar issue, where we need to measure the 
frequency of every cycle of a pulse train running from a few Khz to 
100Khz. We built a dedicated data acquisition system that will do just 
this. It will actually measure 8 independent frequency chains and ship 
the data via USB to a PC. This is referred to a 200Mhz clock (~5nS 
resolution). It took took a while to finish to the thing, but managed 
to pack it into an CPLD clocked at 200Mhz. It also has 6 CH of analog 
input +/- 10V at 14bit resolution at up to 125Khz sample rate, just 
for extra stuff one might want to add in...

Something like this is probably overkill for your application, but is 
possible to pack it all into one chip. If you were doing one channel, 
it'd be pretty simple to do.

Dan