[time-nuts] Basic question regarding comparing two frequencies

Mark Spencer mspencer12345 at yahoo.ca
Sat Jul 24 14:01:29 EDT 2010


Thanks.  I'll try that, with the x10 trace magnifier turned on my scope can 
resolve down to 2ns per division so that should work.


----- Original Message ----
From: Bob Camp <lists at rtty.us>
To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
Sent: Sat, July 24, 2010 10:51:21 AM
Subject: Re: [time-nuts] Basic question regarding comparing two frequencies

Hi

If you have a fast enough scope you can also use the:

Moved X ns in 10 seconds => X/10 ppb of frequency error. 

Bob


On Jul 24, 2010, at 1:28 PM, 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
> 
> 
> 
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