Convolution Tutorial
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From: Rune Allnor on 2 Jan 2010 11:58 On 1 Jan, 17:08, Greg Heath <he...(a)alumni.brown.edu> wrote: > Before the submission I was assigned to a new boss > that had just come back from a 2-year stint at a radar > installation in the south pacific. He looked at my draft, > shook his head and snickered. He said "Have you ever > seen a real missile warhead?". ... He just smiled and walked away > with his head shaking from side to side. .... > To make a long story short: Sometimes the connection > between theory and the real world is very, very tenuous. In your defence - not too many people get to see those kinds of things up close. I used to work with tracking submerged sound sources at sea. The theory is a bit elaborate, but not impossible if one knows what one is doing. The problem is that the tehory is simplified ad absurdum: - Water is a highly dynamic medium, whereas it is modeled as a constant. - The sea surface is almost always rough at several scales, from RMS height centimeters to several meters, and coherence lengths from a coule of meters to several hundred meters. - The sea bottom is a random, mostly unknown surface, and the bottom reflection properties are random, mostly unknown - There are lots of sources and scatterers present in the water column as well as on and in the bottom - The oceanography varies with location (e.g. around river estuaries) and with time (e.g. due to tides) Even the models that attempt to include some of these effects are oversimplified beyond usefulness for practical work. Nonetheless, people are talking about using models to infer all kinds of informations at sea. All it takes is somebody to actually go to sea and contemplate the environment they experience. Rune
From: Manny on 2 Jan 2010 12:34 On Dec 27 2009, 3:39 am, brent <buleg...(a)columbus.rr.com> wrote: > I have created a tutorial on the convolution integral. It uses an > interactive flash program with embedded audio files. > > It is located here: > > http://www.fourier-series.com/Convolution/index.html Back to convolution, one very illuminating example is multiplication, and it works nicely for all bases. -Momo
From: Manny on 2 Jan 2010 12:36 And merry christmas and happy new year to all :). Peace,
From: Eric Jacobsen on 2 Jan 2010 12:56 On 1/2/2010 9:58 AM, Rune Allnor wrote: > On 1 Jan, 17:08, Greg Heath<he...(a)alumni.brown.edu> wrote: > >> Before the submission I was assigned to a new boss >> that had just come back from a 2-year stint at a radar >> installation in the south pacific. He looked at my draft, >> shook his head and snickered. He said "Have you ever >> seen a real missile warhead?". ... He just smiled and walked away >> with his head shaking from side to side. > ... >> To make a long story short: Sometimes the connection >> between theory and the real world is very, very tenuous. > > In your defence - not too many people get to see those > kinds of things up close. > > I used to work with tracking submerged sound sources at sea. > The theory is a bit elaborate, but not impossible if one > knows what one is doing. > > The problem is that the tehory is simplified ad absurdum: > > - Water is a highly dynamic medium, whereas it is modeled > as a constant. > - The sea surface is almost always rough at several scales, > from RMS height centimeters to several meters, and coherence > lengths from a coule of meters to several hundred meters. > - The sea bottom is a random, mostly unknown surface, and > the bottom reflection properties are random, mostly unknown > - There are lots of sources and scatterers present in the > water column as well as on and in the bottom > - The oceanography varies with location (e.g. around river > estuaries) and with time (e.g. due to tides) > > Even the models that attempt to include some of these effects > are oversimplified beyond usefulness for practical work. > Nonetheless, people are talking about using models to infer > all kinds of informations at sea. > > All it takes is somebody to actually go to sea and contemplate > the environment they experience. > > Rune Oh, come on, Rune. What you're describing sounds far, far simpler than climate modeling, and lots of people trust that, especially the politicians. Yes, I'm kidding. ;) -- Eric Jacobsen Minister of Algorithms Abineau Communications http://www.abineau.com
From: Greg Heath on 2 Jan 2010 14:32
On Jan 2, 11:58 am, Rune Allnor <all...(a)tele.ntnu.no> wrote: > On 1 Jan, 17:08, Greg Heath <he...(a)alumni.brown.edu> wrote: > > > > > Before the submission I was assigned to a new boss > > that had just come back from a 2-year stint at a radar > > installation in the south pacific. He looked at my draft, > > shook his head and snickered. He said "Have you ever > > seen a real missile warhead?". ... He just smiled and walked away > > with his head shaking from side to side. > ... > > To make a long story short: Sometimes the connection > > between theory and the real world is very, very tenuous. > > In your defence - not too many people get to see those > kinds of things up close. > > I used to work with tracking submerged sound sources at sea. > The theory is a bit elaborate, but not impossible if one > knows what one is doing. > > The problem is that the tehory is simplified ad absurdum: > > - Water is a highly dynamic medium, whereas it is modeled > as a constant. > - The sea surface is almost always rough at several scales, > from RMS height centimeters to several meters, and coherence > lengths from a coule of meters to several hundred meters. > - The sea bottom is a random, mostly unknown surface, and > the bottom reflection properties are random, mostly unknown > - There are lots of sources and scatterers present in the > water column as well as on and in the bottom > - The oceanography varies with location (e.g. around river > estuaries) and with time (e.g. due to tides) > > Even the models that attempt to include some of these effects > are oversimplified beyond usefulness for practical work. > Nonetheless, people are talking about using models to infer > all kinds of informations at sea. > > All it takes is somebody to actually go to sea and contemplate > the environment they experience. I designed shallow water sonars ( high frequency harmonics generated by nonlinearities formed a narrow beanwidth to avoid backscatter from the surface and bottom)) based on that type of model. However, in this project schools of fish were a major concern. Greg |