[time-nuts] Can a VNA be a high resolution frequency counter

[Bob Camp]

Hi

The help file is correct, but possibly a bit misleading. Most of what they show could be done by a computing counter. They have been around long enough that they are a sub $100 ($50?) item these days. Clock jitter is going to be a very real limit doing what they are trying to do.

Bpb

On Nov 13, 2012, at 8:27 PM, Malcolm <g0mic at aol.com> wrote:

> I have been looking at the DG8SAQ VNA for other purposes and it is suggested in the VNWA_Help.pdf  on page 158 that it can be used as a high accuracy / resolution counter. Document available at http://www.sdr-kits.net/vnwasoftware/?20    .
> 
> Ignoring any drift in the TXCO as I would drive it from an external reference source ( GPSDO or Rb derived) of 36 MHz,  being a (junior in knowledge) time nut I added this as another reason to buy the VNA.  However, I do have some reservations and would like the comments of better qualified time nuts and the answers to some questions:-
> 
> 1.  Can the VNA really have that level of resolution?
> 
> 2.   Is the resolution  reduced in the ratio of the measured frequency to the clock frequency e.g. at 360 MHz is the resolution 10 times worse than that at 36 MHz?
> 
> 3.   Are there any other factors that should be taken into account when performing frequency measurement please?
> 
> Whether or not  this feature works is not a deciding factor in my consideration just a possible plus.
> 
> Your comments please ladies and gentlemen.
> 
> Regards
> 
> Malcolm
> G0MIC
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