[time-nuts] Basic question regarding comparing two frequencies

J. Forster jfor at quik.com
Sat Jul 24 19:06:26 EDT 2010


If you have NI card(s) it is easy. National makes the simple SW available
for free. Last time I looked there is a console command line utility and a
VB and C interfaces.

Labview is a different story. A new version is $$$. You can sometimes find
older versions on eBay. Some versions are PW keyed, so be careful. NI has
a stunning selection of virtual instruments for free, I think.

The HP-IB cards are much more problematic. AFAIK, there is little to no SW
support. I have a couple, but only because they are required to run a
specific instrument (a Laser Interferometer) with a PC and HP system SW.

There are also 2nd source GPIB cards (Prologix, etc). The SW support is
spotty, although I'm told that Prologix is pretty good.

FWIW,

-John

==============


> I would agree. GPIB (aka HPIB) is ubiquitous and is a great place to
> start.
> Unfortunately, I haven't gotten that up to the top of my 'to-do' list yet.
> I have a computer, HP and National interface cards, cables, but no time to
> find the software to make everything communicate yet.  I think it has a
> lot
> to do with the fact that I have relatively old HP equipment that is
> relatively 'tongue-tied' but I think I will be able to figure it out once
> I
> get the time.
>
> Certainly the right place to start though, IMO.
>
> Joe
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of J. Forster
> Sent: Saturday, July 24, 2010 5:24 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Basic question regarding comparing two
> frequencies
>
> "..  more generic interface." ??
>
> The vast majority of professional test equipment has GPIB. Virtually
> anything else is an "also ran".
>
> FWIW,
>
> -John
>
> ============
>
>
>> Thanks, I'm glad to hear I am on the right track.   At some point
>> it would
>> be
>> nice to obtain a counter that can measure the drift of the time base in
>> the
>> 5328A.  The 5328A has a GPIB interface but as the display only varies by
>> a
>> few
>> counts I'm not inclined to track down a GPIB adapter just to plot
>> this.)  
>> Hopefully a newer counter would have a more generic interface.
>>
>> Best regards
>> Mark Spencer
>>
>>
>> ----- Original Message ----
>> From: J. L. Trantham <jltran at att.net>
>> To: Discussion of precise time and frequency measurement
>> <time-nuts at febo.com>
>> Sent: Sat, July 24, 2010 1:49:51 PM
>> Subject: Re: [time-nuts] Basic question regarding comparing two
>> frequencies
>>
>> Sounds about right.  One cycle per 5 seconds or about 0.2 Hz difference.
>> Therefore, 9,999,999.8 Hz.
>>
>> I would feed the GPSDO to trigger your scope and look at the output of
>> the
>> time base on one channel of the scope.  You could also look at the GPSDO
>> on
>> the other channel.  Then you could adjust your counter time base to
>> 'freeze'
>> the display.  Probably good to 'align' the counter time base but for
>> long
>> term comparison, probably better to use a counter and plot the
>> difference.
>>
>> Joe
>>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Mark Spencer
>> Sent: Saturday, July 24, 2010 12:29 PM
>> To: time-nuts at febo.com
>> Subject: [time-nuts] Basic question regarding comparing two frequencies
>>
>> 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
>>
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>
>






More information about the time-nuts mailing list