[time-nuts] High rate, high precision/accuracy time interval counter methods

[David]

Wouldn't this be a natural application of a centroid or transition
midpoint timing TDC implemented with a pulse shaper, fast ADC, and
FPGA?

What about sampling inphase and quadrature sine waves?  This should be
more amendable to a microcontroller only solution and if I had to
start working on something immediately, this is what I would try
first.

I assume in the earlier discussion Bruce mentioned these methods since
they are included on his page of the various ways to implement TDCs:

http://www.ko4bb.com/~bruce/TDC.html

On Tue, 3 May 2016 08:40:53 -0700, you wrote:

>HP/Agilent/Keysight laser interferometers
>measure at the kind of rates you are talking
>about and (last time I heard) could divide
>an interference fringe down to 1/512 of a
>wavelength.  As you say, they definitely use
>an ASIC with a ring oscillator.  Perhaps
>there is some way you could repurpose the
>interferometer electronics to make your
>measurement.
>
>You also might consider that over 25 years
>ago, HP developed the 5313X counters with
>interpolators implemented in FPGA's.  The
>FPGA's available now are vastly more
>sophisticated and much faster.  Perhaps there
>is a way you do your ASIC in an FPGA.
>
>If you really do need an ASIC, the best way
>to get that done is to partner with a university
>and have some PhD student design it.  Universities
>often have arrangements to do this.
>
>Rick