Scott, What you have outlined below sounds dangerous to me. Here's why.
We also have used HP8591EM for a few years. We had discovered that care must be taken to establish where the marker is placed to obtain an accurate "auto" reading. We previously had used 5-20 MHz spans, marked the peak signal of interest, and then performed auto measure at marker. We found that there was sometimes a difference of as much as 15 dB between doing this and measuring manually. Later we determined that due to the characteristic of the emission, we needed to narrow the span to somewhere in the range of 100 kHz to perhaps 500 kHz to define the peak of the signal we were interested in prior to activating the auto test at marker function. This produced comparative results of approximately 1 dB between auto and manual measurements. The real issue is to have a sufficiently narrow span to define the peak of the signal of interest. To me that means the peak occupies an area of at least 20% of the display span, i.e., a broad hump. However, it is not sufficient to switch directly from a broad span to a narrow span as the neighboring signal may be a few dB higher in a cluster of emissions. For this reason, I always step down the span incrementally, monitoring neighboring peaks as I go until I have narrowed the span sufficiently to produce a well defined peak signal -- then I measure qp or whatever detector I am interested in (not forgetting to set the span to less than the max span allowed for qp measurements by the instrument algorithm), or run auto measure at marker. By the way, by the time I have done this in my ambient jungle, I have done 75% of the work of the auto test. There is almost 0 benefit to doing auto test at marker. By doing it manually, I do sleep well at night (now). Hope this helps. Don Umbdenstock Sensormatic > ---------- > From: [email protected][SMTP:[email protected]] > Reply To: [email protected] > Sent: Tuesday, September 29, 1998 3:14 PM > To: [email protected] > Subject: Re(2): Conducted Emissions, average method. > > You guys kind of lost me. I program my 8591EM with the antenna, preamp, > cable, limit and whatever factors. I push the measure button and get all > three readings, PK, QP, AVG. I hope I am not off in left field assuming > that my analyzer knows how to make CISPR measurements and I can take the > readings I get as gospel. I manually tune the spectrum, pick a signal and > measure it. I do also spend a lot of time a zero span so I can listen to > the signals. My stuff is pretty easy to pick out once you know it. Whether > it is lin or log, I don't know, log I guess. As for spectral plots, forget > it, not available (no plotter). No computers either, except the Excel > workbook on my desktop. I record the three readings above by hand and > later put them in a spreadsheet. I only do that to make it pretty since > the analyzer has already corrected my signals. So, somebody please tell me > that I am NOT off in left field and can sleep tonight knowing I am OK. > Please? > > Scott > [email protected] > > > > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to [email protected] > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to [email protected], > [email protected], [email protected], or > [email protected] (the list administrators). > --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
