[time-nuts] Counter display resolution

A.H.Schmidt horsts at iinet.net.au
Sat Dec 22 13:16:24 UTC 2007


Mike , this is correct. if you display just under 10Mhz , you have a 
digit better resolution. My counter does the same

The same applies to 1Mhz , 100Mhz , etc . When the counter just has to 
go to the next higher digit, it will loose one digit resolution.

Regards, Horst


Mike Feher wrote:
> Bill -
>
> Sorry if I was vague. I am assuming that the frequency read out is the
> frequency in the display, and, not one over the bus. Regardless of the fact
> that the counter is auto scaling or not, they can only display a fixed
> number of digits. I am also assuming that these are reciprocal type of
> counters. So, given a fixed time base, and a fixed number of digits, if the
> delta f measured is above 10 MHz, then with a 11 digit display, you would
> read 10,000,000.000 Hz plus the offset from that number. So, the observable
> delta f would be at best in the 0.000 Hz range. Now, if the frequency
> measured was slightly below 10 MHz, you would be able to display up to
> 9,999,999.9999 Hz. I am not considering any averaging at this time, just
> what is displayed. So, in this case you should be able to measure down to
> 0.0000 Hz delta f. Hence my statement of the extra LSD being shown. This has
> been my experience. Regards - Mike  
>
>  
>  
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell, NJ, 07731
> 732-886-5960
>  
>  
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of WB6BNQ
> Sent: Saturday, December 22, 2007 7:00 AM
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] Counter display resolution
>
> Mike,
>
> Your statement about "counters" is rather general and misleading.  You need
> to
> explain your comment better.
>
> For instance, are your referring to the input signal or did you mean having
> the
> internal reference frequency  offset from a standard value ?  All the
> counters I
> have do not "auto-scale" which is what it sounds like your counter is doing.
> However, you do not mention the word "scaling" or "auto" in your statement.
>
> In all of my counters the digits displayed is what you get no matter what
> frequency is being observed.  There is no gain in resolution by being
> slightly
> lower then or any loss by being higher then some arbitrary point.
>
> For the sake of the less skilled that might be on the list -server, could
> you
> explain in more clear detail what you were eluding to ?
>
> Thank you ... Bill....WB6BNQ
>
> Mike Feher wrote:
>
>   
>> Bob -
>>
>> With most counters, I have found that running them at slightly less than
>>     
> 10
>   
>> MHz gives you an extra displayed digit of resolution. If the "1" out of 10
>> MHz were to be displayed, it would take up one more digit in the MSD
>> position, leaving you one less in the LSD position. Since the numbers are
>>     
> so
>   
>> close anyway, if measuring for stability, I personally would prefer that
>> extra digit in the LSD position. Regards - Mike
>>
>>
>>
>> Mike B. Feher, N4FS
>> 89 Arnold Blvd.
>> Howell, NJ, 07731
>> 732-886-5960
>>
>>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Robert E. Martinson
>> Sent: Saturday, December 22, 2007 1:57 AM
>> To: 'Discussion of precise time and frequency measurement'
>> Subject: Re: [time-nuts] HP 5370B question
>>
>> I ran my 5370B for one hour, counting its own reference with a one second
>> gate.  The summary of the results are:
>>
>> min     9999999.99650  Hz
>> max     9999999.99963  Hz
>> avg     9999999.99796  Hz
>> median  9999999.99787  Hz
>>
>> Per the manual's  Performance Test 5 (page 4-12) the spec is +/- 0.005 Hz.
>> It would be nice if my average was 10,000,000.000 HZ but??  From a
>>     
> Time-nuts
>   
>> thread of several months ago, the adjustment for this result is very
>>     
> touchy
>   
>> and it's likely you will make the result worse rather then better.  Since
>> mine is in spec, I'll leave it alone.
>>
>> I have sent the graphical & raw data to Corby, if anybody else is
>>     
> interested
>   
>> please advise me of your email address.
>>
>> Regards,
>> Bob Martinson, N1VQR
>>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of corby d dawson
>> Sent: Wednesday, December 19, 2007 2:15 PM
>> To: time-nuts at febo.com
>> Subject: [time-nuts] HP 5370B question
>>
>> Hi,
>>
>> Could a few of the 5370B owners connect the counters reference output to
>> its counting input jack and with a 1 second gate let me know what the
>> last 2 digits are doing?
>>
>> An earlier post implied that the last couple digits will wander around
>> due to the way its designed.
>>
>> I'd like to know what a couple different counters show to see if that is
>> indeed true!
>>
>> Thanks,
>>
>> Corby Dawson
>>
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>
>
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