[time-nuts] Basic question regarding comparing two frequencies

[Leigh L. Klotz, Jr WA5ZNU]

  This is close to the project I showed at the SF Bay Area Maker Faire 
in May.
I showed fractional ppb difference measurements using a $25 flea market 
scope.

The photo below is by a former NIST Cs fountain researcher who stopped by:
http://www.flickr.com/photos/oskay/4640673869/in/set-72157623988565617/


Leigh/WA5ZNU

On 07/24/2010 10:28 AM, Mark Spencer wrote:
> Hello:
>
> Just for grins I decided to compare the frquency from my GPSDO to the time base
> in my 5328A counter.   
>
>
> I connected the 10 mhz time base from the counter to channel A of my 100 Mhz
> scope, fed the 10 mhz signal from my GPSDO into Channel B and with a T adaptor
> also fed this signal into the input of the counter.    I scope to trigger from
> Channel B.  
>
>
> The drift betwen the two signals on the scope seems to match the error in the
> displayed frquency on the counter.  (ie. if the counter shows 9999.9998 it takes
> approx 5 seconds for the the wave form on channel A to slip a full cycle
> realitve to channel B.)  
>
>
> Is this a reasonable approach or is there a better way to compare two
> frequencies using a scope ?
>
> Best regards
> Mark Spencer
>