# How is quasi peak calculated

As said in the headline, how is quasi-peak calculated?

I was not lucky on google this time, so I will ask here.

I'm just looking for the formulas behind the calculation, since I want to make some simulation in Matlab.

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Quasi-peak means 'not quite peak'.

It is intended to detect peaks that exceed a certain duration in RF with pulse amplitudes using a low pass filter, defined for EMC calibration testers and used to shape spectral curves for Audio Noise. The weight is served to emphasize the peaks that cause most of the nuisance noises. There are other interpretations depending on the field of application.

I recall seeing this in the early 80's in a Paoli, PA Burroughs EMC test facility. Spike bursts of radiation usually got partially suppressed so extended bursts got detected. The RC time constant was probably in the <1 millisecond range or <5% duty cycle (est)

This expert also has a lot to say about it but still has questions on the formulae. http://www.ieee.org/organizations/pubs/newsletters/emcs/summer01/pp.bronaugh.htm

Of course this has the acceptance criteria for quasi-peak, http://www.dbicorporation.com/ite.htm but not the calibration test or criteria for Quasi, which may be defined in this http://goo.gl/qxRR0

I think there is a quasi-analogical reasonâ„˘ ;) why the specification for quasi is not readily available, so if you dont find one, I would use model it with 1st order LPF = T1 and decay to zero time constant T2. My best guess is 100uS for T1 and 10mS for T2.

Rationale for quasi-analogical is idiopathic. quasi-humour

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I am also looking for this answer... Here is something I found that does actually include some formulas. I haven't found a direct conversion (it depends on the QP circuit, which I believe is defined by the standard you'd be using, e.g. CISPR 22), but it has formulas for each one in a table on page 6.

http://www.isplc.org/docsearch/Proceedings/2000/pdf/0595_001.pdf

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 I found another pdf which describes it very good: adv-radio-sci.net/2/27/2004/ars-2-27-2004.pdf – JakobJ Jun 7 '12 at 16:51