Ouch! if the origin of the potentially offending tone is an upper harmonic of a crystal source and all the units you just tested used the high quality Bulova IC which had a very well-behaved 50-50 duty cycle the power in the offending 6th harmonic is zero, thus the reading is also zero, or quite low.
Then, since Engineering did not spec the duty cycle of the Clock Chip, Purchasing bought a whole bunch from ?? that cost half as much, but had a duty cycle of 35-65 and ZAP!! suddenly there is a huge amount of energy at the 6th harmonic which unbeknownst to anybody now finds its way out. So how do you think in terms of statistical variance in such a situation? It's a little like predicting where the curb is by measuring the slope at the center of the road. Just very, very difficult to get there from here. Robert On Tue, 3 Jul 2007 02:46:41 -0000 "Conway, Patrick R (Houston)" <[email protected]> wrote: > That is a great answer, the best so far regarding > statistical nature of > our field (pardon the pun). > Although not a fan of the measurement uncertainty cult > within > our discipline, I understand the intention and support > the result. > > > It seems to me we are still missing 1/2 of the > "statistical" picture. > Here is what I think - > (I could be whacked out here- so please view this with > a > large portion of skepticism...) > I think the measurement "system" includes two items: > a) the measurement facility, and > b) the EUT. > > I think the "measurement uncertainty" does a good job of > defining > quantity a). > But how do we define b), the variance of a product from > an > assembly line? > > > The reason this is important to me is that I do not own, > operate or work > in a test lab. > So the only part of the above equation I can influence > is the b) > part. > (that is of course, assuming that there truly is two > parts to > this "system", and I'm not whacked ) > (- THAT may be too much to assume!) > > Has anyone on this list performed measurement to > understand the > statistical RF nature of the EUT? > I have not. > And I'm not sure how I would start. > > > > Best Regards, > > Patrick. > [email protected] > - 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 ______________________________________________________________________
