I read in !emc-pstc that Gelfand, David <david.gelf...@ca.kontron.com> wrote (in <DAE684A26044B6469EF0A1E1565116820F0B63@semsl131>) about 'Demodulating RF', on Fri, 4 Jan 2002: >This is very interesting. I had a terrible battle with rf conducted >immunity. Could you describe your experiment?
Well, it could be said to be very crude. I made a 20 dB gain amplifier on a scrap of board, and monitored the audio output produced by an r.f. signal modulated at 1 kHz. This signal was applied to a very small parallel-plate apparatus with plates only 75 mm wide by 120 mm long, separated by 75 mm. The coaxial feeder to this was simply terminated in 50 ohms at the plates, and the amplifier was supported roughly in the centre of the working volume. Since the apparatus is so small, the field strength within it should be reasonably predictable, even at 1 GHz. But what I did was to compare the signal generator outputs required to produce a fixed 1 kHz output voltage from the two amplifiers, one with a 724 and one with an 072 op-amp, so the actual field strength had little effect on the results. The difference was fairly constant at approximately 26 dB, irrespective of frequency and field strength, up to about an estimated 3 V/m. Above that, the difference decreased a little. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk After swimming across the Hellespont, I felt like a Hero. ------------------------------------------- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
