[SQM] firmware update for the SQM-LE

Christopher Kyba christopher.kyba at wew.fu-berlin.de
Wed Feb 1 13:35:12 UTC 2012


Dear SQM-LE users,

I wanted to let you know about a firmware update for the SQM-LE that
has just been released by Unihedron.  Several groups independently
noticed that many SQM-LEs display a strange "jumping" behavior at
around 15 mag/arcsec^2, and it was determined that this behavior is
due to pickup of external electromagnetic fields (e.g. the 50/60 Hz
line signal).  It is possible to correct this "jumping" simply by
averaging the results obtained by the SQM over a minute period, but
with the new firmware update from Unihedron you won't have to do this.
 Instead, the SQM averages several readings itself and reports this
averaged value when you do an "rx" command.

Take a look at the attached plot, comparison.pdf.  The new version of
the firmware allows you to get the old "unaveraged" data using the
"ux" command, and this allowed me to do a direct comparison of the old
and new code as the sun set last night.  You can see that when the sky
got down to about 14.2 mag/arcsec^2 the SQM developed the jumping
behavior, and that with the new code the transition is smooth, and the
jumping is eliminated.

Unihedron has worked to make installing the update as easy as
possible, so I hope that everyone running an SQM-LE will be able to do
it.  Windows and Linux users can do it by downloading the new
Unihedron Device Manager (udm).  (Linux users can also use the older
sqmutil perl program.)  Here are the links to the windows device
manager and the updated firmware:


Windows version here (setup.exe installs program):
 http://unihedron.com/projects/sqm-le/cd/windows/udm/

Linux version here (20Mb file):
 http://unihedron.com/projects/sqm-le/cd/unix/udm

The updated firmware is here:
 http://unihedron.com/projects/sqm-le/cd/utility/SQMLE-4-3-21.hex

The previous firmware is here (in case you want to go back):
 http://unihedron.com/projects/sqm-le/cd/utility/SQMLE-4-3-19.hex


As far as I am aware, the SQM-LU is not affected by this problem, so
you don't have to do anything if you're running an SQM-LU.

Because I think it is so important that all SQM-LE users apply this
patch I'm sending this to several email distribution lists, so I'm
sorry to those of you who receive multiple copies.  If you aren't
already subscribed to the official Unihedron SQM mailing list, maybe
you should sign up today:
http://unihedron.com/cgi-bin/mailman/listinfo/sqm

Wishing you starry skies,

Christopher Kyba
Institute for Space Sciences
Freie Universität Berlin
http://userpage.fu-berlin.de/~kyba/


ps. If you are a light pollution researcher, you may want to subscribe
to the Yahoo light pollution research group.  It's a list for sharing
information about light pollution
research (e.g. sharing announcements about upcoming conferences,
papers that you have had published, looking for collaborators for
grant proposals), and not about dark sky activism, legislation, etc
(which the IDA already does a great job of promoting).  It's not
necessary to have a Yahoo
account to sign up, you can subscribe to the email list simply by
sending a message to LPResearch-subscribe at yahoogroups.com
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