In message <f38c1e8a75404347a126608a8f48af5503097...@mer2-excha2.echostar.com>, dated Tue, 3 Jul 2007, "Grasso, Charles" <[email protected]> writes:
>In the absense of any data, we decided to *strive* for 6dB of margin. >That allows for measurement uncertainty >and a couple of db for manufacturing varience. The proof of the pudding... It is most unlikely that a practicable margin could be determined by reasoning alone. You make a reasonable guess, such as 6 dB indeed, and see whether in practice it eliminates problems, from failures when new products are first sent to the test house, through rejections in production testing, to complaints from regulatory authorities. With this approach, as with EMC limits, you can't tell if the requirement is too severe, i.e. you can't tell (usually) if 5 dB margin would still keep you out of trouble. Quality assurance statistics may give a steer. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk There are benefits from being irrational - just ask the square root of 2. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] 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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
