In article <400eb4e1$0$2440$61fed72c@news.rcn.com>, Jerry Avins <jya@ieee.org> wrote:>> >> Luiz Carlos. > >We knew what you meant, but try this one on for size: all real-world >signals are bandlimited. Otherwise, when striking a bell, you would getWell, there might be some IR illumination from the heating generated by the signal decay. But it would be pretty hard to measure if there were any real-world signals were still present as specified by the model once you got down to quantum sizes and durations. IMHO. YMMV. -- Ron Nicholson rhn AT nicholson DOT com http://www.nicholson.com/rhn/ #include <canonical.disclaimer> // only my own opinions, etc.
Fast response filter?
Started by ●January 15, 2004
Reply by ●January 21, 20042004-01-21
Reply by ●January 21, 20042004-01-21
"Ronald H. Nicholson Jr." wrote:> > In article <400eb4e1$0$2440$61fed72c@news.rcn.com>, > Jerry Avins <jya@ieee.org> wrote: > >> > >> Luiz Carlos. > > > >We knew what you meant, but try this one on for size: all real-world > >signals are bandlimited. Otherwise, when striking a bell, you would get > > Well, there might be some IR illumination from the heating generated > by the signal decay. But it would be pretty hard to measure if > there were any real-world signals were still present as specified > by the model once you got down to quantum sizes and durations. >Wouldn't a large chunk of iron emit radio signals if it was vibrating at radio frequencies. Actually, probably a lot worse things would happen. So it would seems safe to conclude that striking a bell does not produce vibrations above a certain frequency . -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =-----
Reply by ●January 21, 20042004-01-21
In article <400ef819_8@corp.newsgroups.com>, jim <"N0sp"@m.sjedging@mwt.net> wrote:>Wouldn't a large chunk of iron emit radio signals if it was vibrating at >radio frequencies.There once was a mystery about why "orbiting" electrons didn't spiral in due to the energy loss from EM radiation emitted by their vibrations. This led to quantum mechanics, which placed a lower size limit on the assumption that the model of nature must be mathematically continuous and determinate. It would be an interesting exercise to see if the frequency response tailed-off to below the levels of quantumly determinate measurement for any physically realisable impulse. IMHO. YMMV. -- Ron Nicholson rhn AT nicholson DOT com http://www.nicholson.com/rhn/ #include <canonical.disclaimer> // only my own opinions, etc.
Reply by ●January 21, 20042004-01-21
On Wed, 21 Jan 2004 12:20:31 -0500, Jerry Avins <jya@ieee.org> wrote:>Luiz Carlos wrote: >> Oops, >> >> Not all periodic signal are bandlimited! >> >> Luiz Carlos. > >We knew what you meant, but try this one on for size: all real-world >signals are bandlimited. Otherwise, when striking a bell, you would get >radio interference, illumination, and X-rays. Math is about models.How do you know you *don't* get radio interference, illumination and X-rays when you strike a bell? Maybe they're just at a really low level, too low for you to detect. Does this come down to the difference between the mathematical idea of zero and the engineering idea of zero? Regards, Allan.
Reply by ●January 22, 20042004-01-22
Allan Herriman <allan.herriman.hates.spam@ctam.com.au.invalid> writes:> How do you know you *don't* get radio interference, illumination and > X-rays when you strike a bell? Maybe they're just at a really low > level, too low for you to detect. > > Does this come down to the difference between the mathematical idea of > zero and the engineering idea of zero?I thought that was what Slepian's paper "On Bandwidth" was all about: in engineering, only terms that have an effect have to be included... once the effect is of the same order as your measurement noise, it can be neglected. Ciao, Peter K. -- Peter J. Kootsookos "I will ignore all ideas for new works [..], the invention of which has reached its limits and for whose improvement I see no further hope." - Julius Frontinus, c. AD 84
Reply by ●January 22, 20042004-01-22
> Luis Carlos, > > Nor are all bandlimited signals periodic..... > > FredHi Fred, Can you give me an example? Luiz Carlos.
Reply by ●January 22, 20042004-01-22
Allan Herriman wrote:> > > How do you know you *don't* get radio interference, illumination and > X-rays when you strike a bell? Maybe they're just at a really low > level, too low for you to detect.What if you just pushed the bell with your finger? What if the bell were made of marshmellows? Would you still expect the frquency response to go to infinity? Under what conditions does striking a bell become mathematically perfect? -jim -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =-----
Reply by ●January 22, 20042004-01-22
Fred Marshall wrote:> "Jerry Avins" <jya@ieee.org> wrote in message > news:400eb4e1$0$2440$61fed72c@news.rcn.com... > > > >>......Otherwise, when striking a bell, you would get >>radio interference, illumination, and X-rays. > > > Jerry .... how in the world .... ???? > > Or, did you have some transformation of energy mechanism in mind that isn't > obvious. > > Were you referring to heat -> IR -> electromagnetic radiation? > > Otherwise, the model generally stays focused on mechanical energy in the > case of a bell and the heat is neglected. Either way bandwidth has nothing > to do with it. Well .... unless there's some mechanism in going to heat / > IR that somehow supports the creation of infinite bandwidths. > > Yeah, I know that supports the point of it being "real". But the example > seems to jump from one type of energy to another without justification. > > I have the feeling that I'm missing something but, as one might expect, > don't know what it is! > > FredI did sort of leave something out. (Big time!) I was thinking of eddy currents in the moving metal caused by the earth's magnetic field, but my mind skipped that paragraph. A steel guitar string won't do very well unless the ends are shorted. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●January 22, 20042004-01-22
jim wrote:> > Allan Herriman wrote: > >> >>How do you know you *don't* get radio interference, illumination and >>X-rays when you strike a bell? Maybe they're just at a really low >>level, too low for you to detect. > > > What if you just pushed the bell with your finger? What if the bell were > made of marshmellows? Would you still expect the frquency response to go > to infinity? > Under what conditions does striking a bell become mathematically > perfect? > > -jimStephan Sprenger once wrote here (when that was still his name), "Papier ist duldig" (paper is compliant), meaning you can write lots of plausible words, but writing doesn't make reality (Hieronymus again). Instead of a bell, bounce a steel ball on a steel plate. If the time of each bounce is 95 percent of the previous one and the first interval is one second, mathematics predicts with fair accuracy that the ball will bounce for 20 seconds. The same calculation predicts a ridiculous number of times the ball bounced. What audio bandwidth do we need to record the sound of this experiment? That depends on the diameter of the ball! Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●January 22, 20042004-01-22
Luiz Carlos wrote:>>Luis Carlos, >> >>Nor are all bandlimited signals periodic..... >> >>Fred > > > Hi Fred, > > Can you give me an example? > > Luiz Carlos.You needn't look far: excite a filter with noise. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
