Grace:
The first part, requesting "Trace Average" is easy. It's the average of 100
traces, in whatever amplitude you are using. If you were to take the average
of two traces, displayed in units of dBm, and saw -32 dBm on the first trace
and -40 dBm on the second trace, then the Trace Average would be -36 dBm.
Obviously, it wouldn't be average power, since the first trace -32 dBm is
really 0.65 microwatts and the second trace -40 dBm is 0.1 microwatts, so the
average power would be 0.37 microwatts, and that is not -36 dBm.
The second part, requesting "power averaging mode" is not so clear. My
assumption would be that power averaging mode means RMS power.
Trying to read the spec's intent, it sounds like you should set your detector
to RMS, set the display to linear milliwatts or microwatts, and average 100
traces.
Note: Life will become difficult if the various trace power levels exceed the
dynamic display range of the analyzer when in linear mode. You might have to
use log mode, and manually read the level of each trace in dBm, then convert
to linear, and average the data set. At 100 traces, it's up to you do decide
if you want to just do it manually or write some custom software to do it
automatically.
Ed Price
[email protected] <blocked::mailto:[email protected]> WB6WSN
NARTE Certified EMC Engineer
Electromagnetic Compatibility Lab
Cubic Defense Applications
San Diego, CA USA
858-505-2780
Military & Avionics EMC Is Our Specialty
________________________________
From: [email protected] [mailto:[email protected]] On Behalf Of Grace
Lin
Sent: Monday, July 13, 2009 4:50 AM
To: [email protected]
Subject: Settings for DTS & UNII Power Measurement per FCC
Dear Members,
Could members please help me to interprete "
Trace average 100 traces in power averaging mode
" under Method #1 of FCC DTS measurement procedure
(http://fjallfoss.fcc.gov/oetcf/kdb/for
s/FTSSearchResultPage.cfm?id=21124&switch=P) and UNII's
(http://hraunfoss.fcc.gov/edocs_public/attachmatch/DA-02-2138A1.pdf)?
Does this refer to Detector = Average, Trace = Average, and Sweep Count
=
100? I haven't figured out "power averaging mode" from my R&S ESU receiver.
ESU has "RMS" under detector choices. I note Agilent spectrum analyzers do
have power average mode.
Thank you and look forward to your help.
Best regards,
Grace Lin
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