Patrick, I don't understand....please explain your statement:
"....................you can't correlate a 3 Meter chamber to a 10 Meter
OATS................."
The only "correlation" necessary is having the required site attenuation
and ground plane parameters. It is the same "correlation" that 10 meter
sites are required to show. If your chamber falls within plus or minus 4 dB
of the NSA tables using volumetric measurements, then you are deemed
"correlated". OATS have the same requirements except that linear
measurements are made instead of volumetric measurements (volumetric
measurements are harsher requirements).
We use independent commercial testing organizations to do our site
attenuation. Here is the process:
1. Site attenuation measurements are made on a 10 meter open area test site
(OATS) that is known to fall within plus or minus 4 dB of the normalized
site attenuation (NSA) tables.
2. If the OATS measures within 4 dB of NSA then the test equipment used to
measure NSA is determined to be "calibrated".
3. The same test equipment is then used to measure our chamber site
attenuation using volumetric measurements.
4. If the site attenuation data falls within 4 dB of NSA then we are deemed
"correlated".
Our site attenuation data has always been within plus or minus 4 dB of NSA.
It is not an inexpensive process either because we have to fly people and
equipment into our site and pay for two NSA measurements each time.
But to answer your question.....................yes, professionally built
chambers using state-of -the-art materials are quite good at measuring
emissions. In some respects, they are superior to OATS.
Bob
======================================================
"Patrick, Al" <al.patr...@sciatl.com> on 08/19/99 02:28:38 PM
Please respond to "Patrick, Al" <al.patr...@sciatl.com>
To: emc-p...@ieee.org
cc: "Patrick, Al" <al.patr...@sciatl.com>
"'alpatr...@op9.com'" <alpatr...@op9.com> (bcc: Robert E.
Heller/US-Corporate/3M/US)
Subject: 3-Meter Chamber for Emission Pre-Scanning
To all members of this distinguished group. I now come to you not to make
commitment but to ask your for help.
My situation is this; I had an OATS site to which I wanted to add a 3
Meter
chamber (ETS Model 20) for Immunity test per the EU requirements.
I started this quest in 1997 and have succeeded with the installation this
month.
Now my problem, along the way my company moved into a new campus (Great!),
But now the CEO does not want an ugly OATS around his new campus. Now just
before approving the new 3 Meter chamber, which took two years to get
thirteen signatures, he says "You can do your scanning in this chamber,
Right!" and looks at me just before he signs it.
Now my eyes roll back in my head and I say (the only thing which will save
this project) "Yes Sir"
Assumptions: The chamber will only be used for pre-scans and diagnostics.
I already know that you can't correlate a 3 Meter chamber to a 10 Meter
OATS, but I have to try at least try until I can build a 10 OATS somewhere.
I would like to hear from members who have used, or tried to use a 3 meter
(10x10x22 FT. chamber lined with ferrite tile) for emission scans.
I have already found that 1 Meter is about the best distant to scan with
out
to many reflections but it's easy to miss an emission too.
I'm "all ears" as they say.
Thank you,
Al Patrick, EMC Lab Manager
Scientific-Atlanta Inc.
al.patr...@sciatl.com
Title: 3-Meter Chamber for Emission Pre-Scanning
To all members of this distinguished group. I now come to you not to make commitment but to ask your for help.
My situation is this; I had an OATS site to which I wanted to add a 3 Meter chamber (ETS Model 20) for Immunity test per the EU requirements.
I started this quest in 1997 and have succeeded with the installation this month.
Now my problem, along the way my company moved into a new campus (Great!), But now the CEO does not want an ugly OATS around his new campus. Now just before approving the new 3 Meter chamber, which took two years to get thirteen signatures, he says "You can do your scanning in this chamber, Right!" and looks at me just before he signs it.
Now my eyes roll back in my head and I say (the only thing which will save this project) "Yes Sir"
Assumptions: The chamber will only be used for pre-scans and diagnostics.
I already know that you can't correlate a 3 Meter chamber to a 10 Meter OATS, but I have to try at least try until I can build a 10 OATS somewhere.
I would like to hear from members who have used, or tried to use a 3 meter (10x10x22 FT. chamber lined with ferrite tile) for emission scans.
I have already found that 1 Meter is about the best distant to scan with out to many reflections but it's easy to miss an emission too.
I'm "all ears" as they say.
Thank you,
Al Patrick, EMC Lab Manager
Scientific-Atlanta Inc.
al.patr...@sciatl.com
