Doug, Very interesting! Can we show something like VI<= constant that is similar to the uncertainty principle in micro-world/quantum mechanisim ? Or it does exist in physics books? I believe that will be very helpful to back up your statements. The paper is basically based on experimental descriptions. Intuitively, we know that a physical quantity must be disturbed when it is measured. How to measure the uncertainty quantitatively? When it is acceptable or not. Thanks, Mick -----Original Message----- From: Doug Smith [mailto:doug@xxxxxxxxxx] Sent: Monday, October 06, 2003 7:32 PM To: SI-List Subject: [SI-LIST] Heisenberg and signal measurements Hi Everyone, It's that time again this month and I have finished my latest article. Most of us worry about probe response when measuring a signal in the lab, but the probe's effect on the signal can be significant, especially for active probes older than a year or two. I have included the abstract for the article below on my site (http://emcesd.com). Page down to the bottom of the index page (past the 80 or 90 other articles) and click on the waveform graphic to read the article. Abstract: Heisenberg's Uncertainty Principle might be adapted in the context of signal measurements to say that one cannot measure a voltage at a node without affecting it. Simulation data is presented to show that under realistic conditions, active probes without damping resistors can significantly affect the signal to be measured. The result can be more serious than just signal loading. ---------- Upcoming event: My 2 day High Frequency Measurements and Noise in Electronic Circuits course at Oxford University in November. For details go to the Oxford site: http://www.conted.ox.ac.uk/cpd/electronics/courses/high_frequency_measuremen ts.asp If the above URL breaks into two lines, use cut and paste to enter the URL into your web browser. Many US airlines are running sales to the UK for as little as about US$200! It may be less expensive to fly from Denver to London than from Denver to Boston in the US. And... Oxford is a great place to visit. Doug -- ------------------------------------------------------- ___ _ Doug Smith \ / ) P.O. Box 1457 ========= Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-----( ) | o | Email: doug@xxxxxxxxxx \ _ / ] \ _ / Website: http://www.dsmith.org ------------------------------------------------------- ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu