This is another small project I have not finished yet, but I am working hard on it...
The aim of this project is to evaluate some of the high-end
oscilloscopes available in our laboratory for suitability in my
research applications, especially for low-noise high-resolution power
analysis.
Very first impression from the Agilent MSO8104A oscilloscope
was really good. The boot time is considerably shorter than for the
Tektronix TDS7254B. The Agilent oscilloscope software (revision
05.20.0001) has some easy-to-use features such as minimisation button
and touch-screen Zoom while the Tektronix software required several
clicks and actions to get there. Data acquisition worked really fast
even for 16MB of the acquisition memory, thus allowing acquire and
average up to 4 trigger events per second while for Tektronix it took
about 3 seconds to acquire each event.
Other advantages of the Agilent MSO8104A oscilloscope: I have a
big list of them and I am going to place it here soon.
Talking about disadvantages of the Agilent oscilloscopes, and
most of other oscilloscopes, I want to mention the customer robbering
feeling for memory upgrades. When you buy the MSO8104A in a standard
configuration (1MB of memory) you already get the oscilloscope
hardware with 128MB of acquisition memory, but the Agilent software
will not allow you to use all this memory until you pay tens of
thousands dollars to Agilent for an enabling code that will tell the
software to expand the use of the memory up to 128MB.
The other horrible thing with the Agilent MSO8104A oscillscope is
the lack of the recovery CDs/DVDs. This is really horrible and puts a
big cross on in-field applications for Agilent oscilloscopes. Just
imagine - you are far away from the Agilent support team and your hard
drive crashes (that actually happens very often especially when RoHS
was introduced and became mandatory, but this is a different story and
probably already a headache for their technical support team). For
some long-term applications this might be very important issue and the
buying decision will be made definitely in favour of Tektronix
oscilloscopes which are fortunately supplied with the recovery CDs.
Other useful things which the Agilent oscillscope might benefit
from is DVD Writer (their cost has dropped significantly these days
and Tektronix does put CD-RW as a default driver). Relying on USB
Flash drives as Agilent offers, is not a good practice as their
failure rate is terribly high, especially for extensive data transfer
use. Luckily, Agilent has a LAN port which can be used to trasfer
large files. However, that requires some experience to set up, plus
availability of a server to hold the files.
So far, I was able to spot only one problem in the Agilent
software for MSO8104A oscilloscope. It is related to incorrect
handling of the Math functions.
For example, I do some measurements with one of the channels
(Channel 3 in the above picture) and define the following two Math
functions: f3 = m3 - 3 (m3 is a copy of the earlier Channel 3
waveform), f4 = intg f3 (integrate). Once enabled, these functions work perfectly.
However, if I repeat acquisitions, sometime the function 'f4'
shows incorrect result as in the picture above.
Going to the Math menu, unchecking the 'Display On' box, then
checking it again helps to restore the 'f4' waveform to the correct
state as it the above picture.
I already notified the Agilent software development team and I
hope the problem will be fixed soon.
Sergei Skorobogatov
<Sergei.Skorobogatov (at) cl.cam.ac.uk>
<Sergei.Skorobogatov (at) hushmail.com>
created 04-05-2007 -- last modified 04-05-2007 -- http://www.cl.cam.ac.uk/~sps32/