Scott, An old rule of thumb from way back says that if you are looking for narrowband signals (defined as narrow with respect to the bandwidth of the receiver), you should not tune in steps larger than 1/2 of the bandwidth you are using. Larger steps may result in missing signals. As FCC radiated emissions testing above 1 GHz is performed with a 1 MHz bandwidth, this would suggest tuning in steps no larger than 500 kHz. When a signal is found, you should then re-tune to determine the actual frequency and maximum amplitude.
The time the receiver sits at each frequency should be determined by several factors. These include the settling time of the detector used (to allow an accurate reading) and any characteristics of the expected emissions that may cause a time variance of the amplitude (need to look long enough to catch the highest reading). Ghery Pettit Intel -----Original Message----- From: scott....@jci.com [mailto:scott....@jci.com] Sent: Thursday, December 06, 2001 5:17 AM To: emc-p...@majordomo.ieee.org Subject: Stepping receiver, step sizes. Hello Group! I would like to ask a question regarding EMI Receiver step sizes in the higher frequency range. We are performing radiated emissions testing in a semi-anechoic chamber using an EMI receiver. We plan to cover a high frequency range between 1 and 5 GHz (a large spanse to cover!). I would like to know what practical step size (ie. 8kHz or 20kHz or 80kHz) I could choose for such a wide range and keep: 1. The data accurate, meaning that I wouldn't be "missing" or stepping around energy by taking to large of a step. 2. Keep the amount of data I'm collecting to a reasonable amount so that I may process it (apply correction factors for antenna, cable loss, pre-amplifier). My question comes up primarily because I haven't found any specifications that require things like minimum scan time, maximum step size, or the like. Is anyone aware of a specification out there that covers this, or have any information/personal experience that could help me make a determination? Thanks for any help in advance! Regards, Scott Mee EMC Engineer Johnson Controls Inc. PH: 616.394.2565 EMAIL: scott....@jci.com ------------------------------------------- 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. ------------------------------------------- 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.
