Hello John, The purpose of a pre-amplifier in the test set-up is to lower the noise floor. I.e. if the over-all noise floor is to high as a result of low gain in the total system, low antenna gain, high cable losses or bad noise figure in the receiving device a pre-amplifier will definitely give a better result. But if the reason for the high noise floor is due to bad shielding of the screened room it will definitely not help. Therefore I asked Russel: Which antenna and measuring receiver/spectrum analyser do you use? Information on those items may help to guide further on the issue.
Best regards Helge Knudsen Test & Approval manager Niros Telecommunication Hirsemarken 5 DK-3520 Farum Denmark Tel +45 44 34 22 51 Fax +45 44 99 28 08 email [email protected] -----Oprindelig meddelelse----- Fra: John Woodgate [mailto:[email protected]] Sendt: 28. februar 2002 08:03 Til: [email protected] Emne: Re: SV: Screened Room Ambient Scans I read in !emc-pstc that [email protected] wrote (in <DCFCB38F97E9CF46 [email protected]>) about 'SV: Screened Room Ambient Scans', on Wed, 27 Feb 2002: >May be you should consider a pre-amplifier. Is there any reason to use a preamplifier apart from the possibility that its noise figure may be better than that of the spectrum analyser? It seems unlikely that it would be much better than that of a CISPR receiver. Or do you mean a preamplifier at the antenna, to send a larger signal to the antenna cable and thus to the analyser or receiver? -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
