OK, but do you think the overload feature is less reliable implemented than the actual read-out of a peak value? Did the manufacturer do a lousy job ? We use an instrument to rely on its features, so do we on the overload feature. It often does the job better than its operating engineer.
My R&S receiver has a two stage warning system: if the readout approaches the end of the linear region (and above) it gives an over-range message, making clear that improved accuracy and reliability can be obtained by adjusting the attenuator. (same for under-range) If you grossly exaggerate the input signal, a overload warning is also given. Maybe the differences between spectrum analyzers and measuring receivers have to be found in this area instead in functional (cispr16) specs, where tend to similar. Regards, Ing. Gert Gremmen ce-test, qualified testing bv Van: Cortland Richmond [mailto:k...@earthlink.net] Verzonden: Friday, December 05, 2008 2:48 AM Aan: Gert Gremmen; Ralph McDiarmid CC: emc-p...@ieee.org Onderwerp: RE: EMI Receiver I believe that relying on a receiver to warn it is in overload is a mistake. It is important that those performing measurements understand not only how to operate a reciever and its software, but also what the receiver is *doing* under control of that software. I've seen errors made during tests that can be attributed to this lack of understanding. One of our duties in such cases (IMO) is to correct them. Cortland Richmond, ka5s cortland.richm...@ge.com My remarks are not those of my employer > [Original Message] > From: Gert Gremmen <g.grem...@cetest.nl> > To: Ralph McDiarmid <ralph.mcdiar...@xantrex.com> > Cc: <emc-p...@ieee.org> > Date: 12/4/2008 1:52:19 PM > Subject: RE: EMI Receiver > > I think this is more a theoretic exercise, > and as true as unlikely to fool you. > > Any decent receiver in overload > does not show a measurement value > but blinks, reports an error condition (IEEE-bus) > or has a bright red blinking error led > or beeper. > > I have never been able to reproduce this > phenomenon with a spectrum analyzer without > reported error condition. (and certainly > not with all signals -spurious included- meeting limit lines, > and make me conclude a compliant result.) > > > > > Gert > > -----Oorspronkelijk bericht----- > Van: emc-p...@ieee.org [mailto:emc-p...@ieee.org] Namens Ralph McDiarmid > Verzonden: donderdag 4 december 2008 17:57 > Aan: emc-p...@ieee.org > Onderwerp: RE: EMI Receiver > > That's my understanding too. > > > Ralph McDiarmid, AScT > Compliance Engineering Group > Xantrex Technology Inc > > -----Original Message----- > From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Clif > Brick > Sent: Thursday, December 04, 2008 8:50 AM > To: Gert Gremmen; emc-p...@ieee.org > Subject: RE: EMI Receiver > > I could be wrong as it's been a few years, but it seems to me that a > spectrum analyzer receiver in overload will show a signal to be a lower > amplitude than it really is (in addition to ghosts, spurs and intermod > products). The issue is one of compression, and in fact an overlaoded > analyzer will show comply when in fact the device is non-compliant just > as readily as the opposite. > > If an overlaod condition exists, you may get a reading of a real (from > the EUT) signal that is say 0dBm, you add 10 dB of attenuation and get > -3dBm. This means that in fact your signal is at least 7dB larger than > your display. If you add 10 dB more and get say -7, you're still in > overload. You would need to continue until you get linear response. > Important to understand is that it may be well outside of the band of > interest that the overlaoding signal is comin in on. This is why > preselection helps.... > > Best regards, > Clif - 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 <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <emcp...@ptcnh.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
