[time-nuts] Comparing the frequency of two gpsdo's.

[EWKehren at aol.com]

Thank you   Will remember it. Thought I had stayed within the  guidelines.  
 Bert 
 
 
In a message dated 11/13/2010 3:45:21 P.M. Eastern Standard Time,  
jra at febo.com writes:

Bert, I  just approved your message, so it should show up soon.  The reason 
for  the size increase is that the internet email format is 7-bit ASCII, so 
a  binary file has to be encoded down from 8 bits and grows as a  result.

John

On Nov 13, 2010, at 3:32 PM, EWKehren at aol.com  wrote:

> Hi
> I give up a 113.3 K picture attachment no text  turns into 157 K. I 
tried.  
> It is particular frustrating when  seeing how much bandwidth is wasted 
with  
> garbage that has  nothing to do with time and frequency.
> Bert Kehren
> 
>  
> In a message dated 11/13/2010 2:14:04 P.M. Eastern Standard  Time,  
> lists at rtty.us writes:
> 
> Hi
>  
> Ok, so right now you are looking at about 10 degrees out  of 360  where 
one 
> cycle is 100 ns. More or less you are in the 3 ns  range.  
> 
> Some cheap stuff that will do better:
>  
> HP 5334
> HP 5335
> HP  5345
> HP 5370
>  HP 5371
> 
> All are in the "sub $300" range on the  normal  sites. Some are sub $100. 
> All are available with GPIB for   logging.
> 
> For a bit more money
> 
> HP  53131
> SR 620
> 
> You may  find one for sub $1000.  Often you see them listed for nutty 
> prices. I  certainly would  not pay anywhere near $1,000 for either one. 
> 
> The one   I'd go for is the 5334. It's smaller than the rest. They likely 
> are  the  cheapest of the group. The ones I have *seem* to be more 
reliable  
> than some of  the rest of the stuff listed. 
> 
>  All of them can run in any one of three  modes:
> 
> 1) PPS  to PPS timing
> 2) PPS to 10 MHz edge timing
> 3) 10  MHz to  10 MHz timing
> 
> Number 2 on the list seems to have the  fewest  issues. 
> 
> A completely different  approach:
> 
> Pump both signals into  a phase detector  (RPD-1 or X-OR or what ever) 
and 
> use a DVM to log the  voltage.  You can get some super  overkill DVM's 
for 
> less than you can  get  any of the counters. They will easily get you 
into the 
> sub  ns range on  resolution. Weather the setup will be accurate at this 
or  
> that  level is  in the "that depends" category.
>  
> Bob
> 
> 
> On Nov 13, 2010, at  11:18 AM,  Mark Spencer wrote:
> 
>> Hello:
>> 
>> I'm  looking  for some advice about ways I can compare the frequency of  
> two gpsdo's.   To date I have been using an oscilloscope  that supports 
phase 
> measurements to  measure the small  (typically 10 degreees or so at 10 
mhz) 
> change in phase  between  the two signals over a period of a few hours 
and then 
> calculating  the  frequency change.
>> 
>> I realize this is sub  optimal but I wanted  to use the gear on hand.   
>  Recently the phase measurement fuction of  my scope has stopped  
working.  
>> 
>> As the useage I have  ever found  for the phase measurement function in 
my 
> scope was comparing  the  frequencies between gpsdo's I'm thinking it 
might 
> be better  to invest in some  other equipment rather then getting the 
scope 
>  fixed.
>> 
>> Any  thoughts as to what could be  obtained used for less than 1K that 
> would be  suited for this  type of measurement ?
>> 
>> Regards
>>  
>> Mark S
>> 
>> 
>> 
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