[time-nuts] HP 5372A vs. 5370A

Ed Palmer ed_palmer at sasktel.net
Wed Feb 9 22:03:01 UTC 2011


The only chance would be to use the binary programming mode, but it 
would only be worthwhile if it would maintain the zero-deadtime 
capability.  I don't know how to confirm if it does or doesn't.  It's on 
my 'round tuit' list to play with, but  it won't be happening  any time 
soon.  Did you get any value out of the 5372A program I sent you last year?

Ed

Bob Camp wrote:
> Hi
>
> We really do need a simple app to "extend" the 5371 and 5372 for longer time
> ranges. If there's one out there, I've certainly missed it as I've looked
> around. 
>
> Bob
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Ed Palmer
> Sent: Wednesday, February 09, 2011 4:14 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] HP 5372A vs. 5370A
>
> If you've got one, it can be hard to justify buying the other unless you 
> have some very specific requirements.  There's a lot of overlap between 
> them.  I have a 5372A and have wondered if it's worth getting a 5370(A 
> or B).  So far, the answer for me is no.
>
> Here are a few things that I've used the 5372A for.
>
> I have a Navsync CW-12 GPS receiver.  I measured 1000 periods of the 
> 1PPS and saw that the Max-Min range is less than 30ns and the Standard 
> Deviation is less than 5 ns.  The minimum, maximum, Mean, RMS, and 
> standard deviation are automatically calculated and shown by the 5372A.  
> By the way, my TBolt has a range of < 4 ns and a Std Dev of  < 1 ns.
>
> The CW-12 also has a 10 MHz output.  I used the Histogram Time Interval 
> function to measure the periods of 100 Million cycles with a resolution 
> of 200ps.  It took less than 30 seconds to measure, process, and display 
> the results.  The results showed that there was a normal distribution 
> around 100 ns and a second normal distribution around 92 ns.  The 
> difference is approximately the period of the internal clock (120 MHz).  
> This told me that the 10 MHz is kept on frequency by occasionally 
> shortening the period by one cycle of the internal clock.  For my unit, 
> this happens about 200 times a second.  I know this by the ratio of the 
> number of long periods to short periods.  This behaviour explains why 
> Navsync warns that this output needs to be cleaned up before using it as 
> a frequency reference.
>
> I routinely use the 5372A to make multiple 1 sec. measurements of 
> frequency or time interval and then dump the results via GPIB for 
> analysis.  Standard stuff for either the 5370 or 5372 except as 
> mentioned elsewhere, these measurements are made with no dead time.
>
> My unit has Option 040 which adds FFT capabilities.  I can do phase 
> noise measurements within the limitations of the 200ps resolution of the 
> box.
>
> The June 2008 issue of Circuit Cellar had an article ("Let's be Crystal 
> Clear") on crystals and oscillators.  The 5372A was used to analyze the 
> startup behaviour of an oscillator.  You should be able to get this 
> article through inter-library loan or maybe there's a copy lurking on 
> the net somewhere.  There are also various manuals and app notes online 
> at the Agilent site.
>
> The biggest limitation of the 5372A is that you can only make 8191 
> frequency measurements or 4095 time interval measurements with each 
> measurement lasting no longer than 8 seconds.  If you want to use it for 
> making more or longer measurements (e.g. long term Allan Deviation 
> measurements) you have to start doing some GPIB programming, but I think 
> you lose the no-dead-time advantage.
>
> If you see a 5372A that's reporting an "Error 160:  Out of sensitivity 
> cal." don't worry about it.  It just means that the onboard lithium 
> battery is dead and needs to be replaced.  The calibration is trivial to do.
>
> The most important thing about either the 5370 or 5372 is to study it.  
> Figure out it's capabilities, limitations, and tricks so that you use it 
> to it's full potential.  I'm still working on that!
>
> Ed
>
> Bert, VE2ZAZ wrote:
>   
>> Hi everyone.
>>
>> I own an HP 5370A. I do GPIB and Labview, KE5FX Utilities, DF6JB's
>>     
> Plotter, 
>   
>> spreadsheets etc. Always looking to improve my setup...
>>
>> Here is a simple question: Why should I try to get an HP 5372A (or 5371A)?
>>     
> What 
>   
>> are the benefits over the 5370A? Worth spending?
>>
>> Thanks in advance,
>>
>> Bert.
>>
>>
>>
>>
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