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Hi All,<br><br>
Well I have been seeing these steps (or temporary offsets) off & on
for a couple of years. I thought they were only seen on the older
Applied MEMS accelerometers. We had this problem in a couple of the
MEMS used in the Wells, Nevada, deployment. After the deployment I
sent the MEMS (5) in for repair Fall 2009. The explanation was that
some contacts inside the MEMS were "dirty". They were
cleaned. After I received them back I checked them out and they all
appeared to not have the steps. The generation of Applied MEMS
should not have this trouble I was informed.<br><br>
I sent some of these systems to Am Samoa. On their return a couple
of them have the steps again. Below is a plot of one of them with
steps happening quite frequently. This system had no communications
with Ethernet record disabled but the RT-130 TCP/IP stack power was left
set to "on". Not sure if this has any connection but I
doubt it. I should test it. Here is the plot:<br>
<img src="cid:.0" width=1024 height=768 alt="Emacs!"><br><br>
MArk<br><br>
At 22:03 2/27/2010, Dave Drobeck wrote:<br>
<blockquote type=cite class=cite cite="">We definitely have seen it on
Episensors and the Geotech PA-23. Problem <br>
seemed to be solved by making sure the sensors have well regulated power,
but <br>
now we seem to be seeing it (at about 30 counts only) even with regulated
<br>
power in a few cases. We've not had time to investigate that
yet. In the <br>
Geotech case there was no question it was related to the Freewave radio
<br>
transmitting and briefly pulling down power as we could vary the size of
the <br>
data packet and the noise tracked perfectly with the radio
transmitting. <br>
Installing the regulator took care of it.<br>
Dave<br><br>
On Thursday 25 February 2010 05:48 pm, Don Farrell wrote:<br>
> Hello to all,<br>
> Are
there any networks that are seeing electronic stepping on<br>
> velocity or acceleration sensors and data loggers? So far
the<br>
> Kinemetrics EpiSensors are the most vulnerable with one of the<br>
> triaxial directions sometimes showing a greater amplitude. Most<br>
> problems are with Nanometrics HRDs with Episensors, Ref Tek<br>
> 130-ANSS/02/6 data loggers with Mark products L4s and some
broadband<br>
> sensors. Freewave radios seem to be the cause of most of the
problems<br>
> but paging transmitters and SCADA are possible sources. A cell
modem<br>
> with a Ref Tek twenty feet underground causes stepping on the
MEMS<br>
> sensors. A recent switch to a Freewave FGRplusRE model
resulted in<br>
> stepping on one channel of a K2 and on an external vertical
Mark<br>
> Products L4. Ferrite cores rarely solve the problem. A
separate<br>
> solar panel and battery to power the external sensors can
eliminate<br>
> or lower the amplitude of the steps. In a recent experiment a
test<br>
> box with a 5 Hz sine wave output into an HRD showed stepping.<br>
> Shorting the inputs in the test box still showed stepping on the
HRD<br>
> channels. If you have seen this problem do you have any
additional<br>
> ways of eliminating it? Seismograms and PSD plots are attached.<br>
> --<br>
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