Most likely the case, but not entirely. The OP was about a QP measurement, which implies a broadband signal. If that signal were large enough, it alone could overload and desensitize the receiver as the first respondent mentioned. This could be checked during the initial peak detection pre-scan, with enough attenuation to guarantee a linear measurement, and then depending on the result, an informed decision could be made whether a preselector was necessary with enough attenuation removed to make a good measurement.
Note that in this scenario, the preselector must be narrow enough to protect against the spectrum of the signal to which we are tuned, as opposed to rejecting a completely different out-of-band signal. This requires a tunable front end, not a series of fixed bandpass filters as is common in many bands nowadays. Ken Javor Phone: (256) 650-5261 From: Ken Wyatt <[email protected]> Reply-To: Ken Wyatt <[email protected]> Date: Thu, 22 Oct 2015 13:22:45 -0600 To: <[email protected]> Subject: Re: [PSES] Preselector requirement in ANSIC63.4 -low PRF I would think that if the measurements were taken in a chamber and the product emissions were characterized and amplitudes known and the analyzer was a good quality one, justification could be made to eliminate the preselector. I suspect the requirement was established during the days we all were using OATS. Kenneth Wyatt Woodland Park, CO Sent from my iPhone. On Oct 22, 2015, at 12:58 PM, Sundstrom, Mike <[email protected]> wrote: > So the SA is not in overload, which could give a wrong amplitude otherwise. > > > Thanks, > > Michael Sundstrom > Garmin Compliance Engineer > 2-2606 > (913) 440-1540 > KB5UKT > > ³Never give up on a dream just because of the time it will take to accomplish > it. > The time will pass anyway.² > Earl Nightingale > > > From: Grasso, Charles [mailto:[email protected]] > Sent: Thursday, October 22, 2015 1:53 PM > To: [email protected] > Subject: [PSES] Preselector requirement in ANSIC63.4 -low PRF > > Hell all, > > ANSI C63 *requires* the use of a preselector on an SA when making QP > measurements > of a signal with a low repetition rate (lower than 20Hz or less). Does anyone > know why? > > Best Regards > Charles Grasso > Compliance Engineer > Echostar Communications > (w) 303-706-5467 > (c) 303-204-2974 > (t) [email protected] > (e) [email protected] > (e2) [email protected] > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. 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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) <http://www.ieee-pses.org/list.html> > 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) <http://www.ieee-pses.org/list.html> 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]>
