This is how CISPR16-1 writes about it:

"6.4.1 Amplitude relationship
Up to 1 000 MHz, the average detector is defined as follows:
(linear average): 
the response of the measuring receiver to pulses of repetition rate nHz 
and impulse area of 1,4/n 
mVs  at 50 ohm source impedance, shall be equal to the response of an 
unmodulated sine-wave signal
at the tuned frequency having an rms value of 2 mV [66 dB(μV)]. "

"A tolerance of 2,5 dB/–0,5 dB is permitted on the sine-wave voltage 
level."

Note the fairly generous tolerance for the sinewave reference level.
_____________________________________________________________________________________
 


Ralph McDiarmid  |   Schneider Electric   |  Renewable Energies Business | 
  CANADA  |   Regulatory Compliance Engineering




From:
Ken Javor <ken.ja...@emccompliance.com>
To:
EMC-PSTC@LISTSERV.IEEE.ORG
Date:
12/06/2011 02:56 PM
Subject:
Re: [PSES] Average detector/s



I don’t know what it is, but would expect the definition of the average 
detector, meaning the time constant, is in CISRR 16-1.
 
Ken Javor

Phone: (256) 650-5261


From: Bill Owsley <wdows...@yahoo.com>
Reply-To: Bill Owsley <wdows...@yahoo.com>
Date: Tue, 6 Dec 2011 14:23:20 -0800 (PST)
To: Ken Javor <ken.ja...@emccompliance.com>, "EMC-PSTC@LISTSERV.IEEE.ORG" 
<EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: Re: [PSES] Average detector/s

Indeed it does.  The measured signal in this particular case is broadband 
stuff of a modulated carrier.
So far I can get a 20 dB spread when measuring the signal with all the 
different buttons and techniques available for average.
And you know the limit falls right in the middle !!  And the fingers start 
pointing...

The instrument manual says the average detector finds the average of 
everything in each measuring window and reports that.
"instantaneous" average ?!?!  And then do a trace max hold on that, and it 
begins to look similar to peak.
Now if I turn on averaging over time, for instance a running average of a 
100 runs, The reported value settles down nicely. 
But, I suspect any interference has already happened.
Or, If I slow the sweep time down, then the same settling occurs as each 
window is averaged during the measurement dwell and that number is 
reported. 

I have not found a reference to an averaging time.  Is there one? 


 
 
  
 From: Ken Javor <ken.ja...@emccompliance.com>
 To: EMC-PSTC@LISTSERV.IEEE.ORG 
 Sent: Tuesday, December 6, 2011 4:43 PM
 Subject: Re: [PSES] Average detector/s
  
Re: [PSES] Average detector/s 
If video averaging is done with a log amplifier instead of linear, then a 
geometric mean is taken rather than an arithmetic mean, the latter being 
an average detector.  Both means naturally yield the same output with a cw 
input, but as the variation in the averaged quantities gets greater 
(standard deviation increases) the difference between the two types of 
means gets larger and larger.  Hence, for an intermittent broadband signal 
of high amplitude but very low duty cycle and duration, one would expect 
very different outputs when using the log display vs. linear.
 
Ken Javor

Phone: (256) 650-5261


From: <ralph.mcdiar...@schneider-electric.com>
Date: Tue, 6 Dec 2011 11:15:40 -0800
To: Bill Owsley <wdows...@yahoo.com>
Cc: <EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: Re: [PSES] Average detector/s


For in-house pre-compliance testing, we use a VBW of 10Hz to approximate 
the time response of an AVG detector.  Seems to work quite well.
_____________________________________________________________________________________
 


Ralph McDiarmid  |  Schneider Electric  |  Renewable Energies Business  |  
CANADA  |   Regulatory Compliance Engineering 


From: Bill Owsley <wdows...@yahoo.com> 
To: EMC-PSTC@LISTSERV.IEEE.ORG 
Date: 12/06/2011 09:15 AM 
Subject: [PSES] Average detector/s 



Quasi-peak was fun, so now let's have fun with the Average detector/s, 
each and all of them ! 

For reference, EN 302 208-1, Sec. 8.3, 8.4, 8.5. 
Detection mode: Averaging 

Which averaging would this be?  On the SA that I'm using, 
There is video averaging by reducing the VBW to something a lot smaller 
than RBW. 
There is EMI average detector, and 
There is average detector which has two modes, power and video. 
(one is the log of the average of power, the other is the average of the 
log of power.) 
And there is a multiple sweep averaging of the above. 
And there is adjusting the sweep time while averaging is turned on. 
And adjusting the span to be measured has an effect on the average 
measurement. 

Each can give a different result. 

So starting with the always correct answer in EMC, "it depends,"  what are 
these dependencies? 






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