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

Bob Camp lists at rtty.us
Wed Feb 9 21:36:13 UTC 2011


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.
>
>
>
>
> _______________________________________________
> 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_lists.febo.com mailing list