The correct wording is the rms equivalent of the peak of the modulation envelope. That is what your spectrum analyzer or EMI receiver is calibrated to read. Ditto your field intensity sensor. The only difference there is the physical response time of the sensor element. If it is slow wrt the modulation waveform, it does an unwanted average.
This is checked and accounted for by measuring the field intensity reading unmodulated, then applying modulation and looking for any difference. If there is a difference, that factor has to be applied when reading the field intensity back. For instance, if the target is 200 V/m and the modulation is 50% duty cycle pulse at 1 kHz rate, if the sensor is fast enough it will report 200 V/m, the same as no modulation. But if it is slower, it will be down a little, say 141.4 V/m, and then that is the target you are leveling on instead of 200 V/m. The ratio of peak-to-rms of a sine wave has NOTHING to do with any of this. Ken Javor Phone: (256) 650-5261 > From: David <[email protected]> > Reply-To: David <[email protected]> > Date: Mon, 11 Mar 2019 20:25:58 +0000 > To: <[email protected]> > Subject: [PSES] RTCA modulation measurement for Sec 20 > > RTCA experts I¹m trying to figure out if I am > reading Section 20 correctly with regard to modulation and test level. > > Section 20.3 c) has the below, and Figure 20-5 > is attached. > > The amplitudes associated > with the categories are based on the peak of the rms envelope over the > complete > modulation period as shown in Figure 20-5. Amplitude measurements shall > be made in a manner which clearly establishes the peak amplitude of the > modulated waveform. > > > For radiated susceptibility, the field probe is > reading RMS - so you calibrate to the correct level per 20.3 and 20-5, then > playback your forward power. > > For conducted though, your calibration is done > with a receiver, spectrum analyzer, or power meter. Those can measure peak or > average. If you calibrate by measuring peak on the spectrum analyzer, do you > have to divide the category level by .707 to set the required value? So for > example, Cat Y at 300 mA would actually need to be 424.3 mA on your spectrum > analyzer(ignoring pads, etc.)? If you calibrate in peak without using the .707 > factor are you under testing? > Thanks,David > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. To post a message to the list, send your e-mail to > <[email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used > formats), large files, etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher: <[email protected]> > David Heald: <[email protected]> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
