Pre-selectors offered on EMI receivers on the market today do not fulfill the function of allowing a weak signal to be measured in the presence of a nearby strong signal. Especially in the microwave bands, the “pre-selector” is nothing more than a small set of fixed bandpass filters, and even where they provide a tuning pre-selector below 1 GHz, it will be 50 MHz wide or larger. The original idea of a pre-selector BW being maybe ten times the widest available IF BW seems to be extinct.
That being said, if measurements are being made inside a chamber the lack of a pre-selector shouldn’t cause too much of a problem. Where a real pre-selector is very useful is on an OATS, when using an impulse generator to calibrate the receiver, or doing a test like MIL-STD-461 CE106. Ken Javor Phone: (256) 650-5261 ________________________________ From: Jason Smith <[email protected]> List-Post: [email protected] List-Post: [email protected] List-Post: [email protected] Date: Thu, 2 Sep 2010 10:58:44 -0400 To: <[email protected]>, <[email protected]> Conversation: Preselector Subject: RE: Preselector There is nothing that dictates a pre selector must be used in the standard. The standard is written so that as long as you can make the required measurements it does not mater what technology you use. But historically a preselector has been the only way to meet the CISPR requirements. This is no longer true, there is at least one (that I know of) certified CISPR receiver that does not use one. Thank you, Jason H. Smith Manager Applications Engineer ar rf/microwave instrumentation ________________________________ From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Thursday, September 02, 2010 9:01 AM To: [email protected] Subject: Preselector I have a vendor that is telling me that a preselector for your EMI receiver is required for compliant testing for radiated emissions for Europe. I don't see anything in CISPR 16 stating this. Is the vendor correct? Bob Heller St. Paul, MN 55107-1208 Tel: 651- 778-6336 Fax: 651-778-6252 - 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.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 <[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.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 <[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.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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]>
