An intriguing story about undersampling

Started by erine June 5, 2005
Read this astonishing story at 
http://spazioscuola.altervista.org/UndersamplingAR/UndersamplingAR.htm
Here it is an excerpt:
A STORY ABOUT UNDERSAMPLING

by Angelo Ricotta - Rome, Italy

a.ricotta@isac.cnr.it

ITALIAN VERSION



In the article "Turning Nyquist upside down by undersampling" by Bonnie 
Baker, EDN 12 May 2005, are reported the two formulae  and  to compute an 
allowable sampling frequency for undersampling a bandpass signal. I was 
surprised by that because I have been using the



 undersampling technique since the late seventies and even wrote a report 
(Angelo Ricotta, "Some remarks on the sampling and processing of SODAR data", 
Technical Report, IFA-CNR, July 1983) where I gave two simple and practical 
formulae to compute all the allowable sampling frequencies for undersampling 
a given bandpass signal. The report was written in Italian and was known, at 
least, among the Italian community working on SODAR systems in which a few 
people and even students utilized my formulae in an unfair way because they 
did not mention the source. On 10 October and 7 December 1991, also to stop 
the above misuses, I sent two letters, containing my formulae for 
undersampling, to EDN Signals & Noise Editor but I never received an answer. 
On 25 March 1994 I attended a Burr-Brown's Applications Seminar in Rome, 
Italy, where I explained to the two relators my formulae. One of the 
relators, Mr. Jason Albanus, suggested to me to send my formulae to Mr. 
Jerry Horn at Burr-Brown Corp., Tucson, Arizona, for inclusion in future 
seminar books. I did this way but my letter was never acknowledged. Then on 
11 July 1994, on Electronic Design, appeared an article by George Hill of 
Burr-Brown Corp., Tucson, Arizona, in which he exposed, at  p.77, my 
formulae for undersampling, stating literally: "After a recent applications 
seminar given by Burr-Brown in Rome, Italy, one of the attendees suggested 
an approach for easily calculating appropriate sampling rates for 
undersampling any specified range of input frequencies. He offered his ideas 
for inclusion in future seminars, but didn't authorize us to use his name. 
Here is his approach.". Of course I was that attendee and for me was clear 
that Mr. George Hill and everyone else should have used my name in 
connection with my formulae! For that on 13 September 1994 I wrote to Mr. 
George Hill inviting him to do so, but again no answer.

Anyway, the formulae I proposed are the straightforward mathematical 
translation of the "fan-fold paper model" (Ref.2), which is a direct 
consequence of Shannon and Nyquist theorems: more precisely, the sampling 
theorem was formulated by Nyquist in 1928 and mathematically proven by 
Shannon in 1949. My interest on signal processing started in the mid of 1975 
when I began doing my doctoral thesis (Ref.5) which consisted in the design 
and in the realization of a SODAR system for use in atmospheric boundary 
layer studies. For the hardware I basically followed the work done by 
E.J.Owens (Ref.6). During the 1976 this first version of SODAR was 
extensively used in measurement campaigns and at this point emerged the need 
of an efficient sampling and processing of the data, especially because we 
had old computers with slow A/D and poor storage units! My first approach 
was hardware in that I realized an audio heterodyne that worked well. I was 
the first in Italy to build a SODAR system that worked well and even today 
many people use my technical solutions even if not all of them recognize it. 
In 1979 I was designing a new version of the SODAR system when I ran into 
Ref.2, p.230, and imagined the "fan-fold paper model", that I named 
"soffietto" in Italian (Ref.4), from which I deduced the formulae for 
undersampling presented here. Only much more later I read Ref.1 and Ref.3 
and realized that they where already known, even if the topic was treated 
differently and partially and without proof in the quoted references, 
instead I think my proof is simple and smart. The Ref.1 stated the 
fundamental formula in the time domain instead of frequency domain, as I 
did. Furthermore no formula for  is given. In the Ref.3 the undersampling is 
listed among the problems left to the reader and the formula shown refers 
only to the lowest sampling frequency, but one of the terms suggests the way 
to compute . Then I think of my small contribution to undersampling as 
simplifying and clarifying the topic for the practical use, but it should 
not be underevaluated or ignored or, worse, usurped.


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"erine" <erine@hotmail.com> wrote in message 
news:_yxoe.134020$IN.2310899@twister2.libero.it...

> Then I think of my small contribution to undersampling as > simplifying and clarifying the topic for the practical > use, but it > should not be underevaluated or ignored or, worse, > usurped. >
You aren't alone. There's a lot of good work that was done in the 60s and 70s that has been lost and more will be lost as engineers from that era retire and die. As in your case, the wheel will be re-invented, probably more than once. With any luck, global connectivity and vastly improved searchable archives will make this phenomenon an artifact of a time when knowledge was exploding faster than it could be published, catalogued and distributed.
John E. Hadstate wrote:

> "erine" <erine@hotmail.com> wrote in message > news:_yxoe.134020$IN.2310899@twister2.libero.it... > > >>Then I think of my small contribution to undersampling as >>simplifying and clarifying the topic for the practical >>use, but it >>should not be underevaluated or ignored or, worse, >>usurped. >> > > > You aren't alone. There's a lot of good work that was done > in the 60s and 70s that has been lost and more will be lost > as engineers from that era retire and die. As in your case, > the wheel will be re-invented, probably more than once. > With any luck, global connectivity and vastly improved > searchable archives will make this phenomenon an artifact of > a time when knowledge was exploding faster than it could be > published, catalogued and distributed. > > >
While investigating speech I've "discovered" formants. I'm currently interested in GPS. I suspect I'm about to "discover" the ionosphere. After compensating for ionosphere, I suspect I will "discover" the troposphere. It is very *EDUCATIONAL".
"Richard Owlett" <rowlett@atlascomm.net> wrote in message 
news:11a6lnggpuktv57@corp.supernews.com...
> John E. Hadstate wrote: > >> You aren't alone. There's a lot of good work that was >> done in the 60s and 70s that has been lost and more will >> be lost as engineers from that era retire and die. As in >> your case, the wheel will be re-invented, probably more >> than once. With any luck, global connectivity and vastly >> improved searchable archives will make this phenomenon an >> artifact of a time when knowledge was exploding faster >> than it could be published, catalogued and distributed. >> > > While investigating speech I've "discovered" formants. > I'm currently interested in GPS. I suspect I'm about to > "discover" the ionosphere. > After compensating for ionosphere, I suspect I will > "discover" the troposphere. > > It is very *EDUCATIONAL". >
Absolutely right. However, you probably will not *have to* expend the same amount of effort going down wrong paths and getting stuck in blind alleys that the original discoverers did. You have a bigger choice of what to take at face value and re-use, and what to throw away and re-discover. It's the curse of the double-edged sword.
"Richard Owlett" <rowlett@atlascomm.net> wrote in message
news:11a6lnggpuktv57@corp.supernews.com...
> John E. Hadstate wrote: > > > "erine" <erine@hotmail.com> wrote in message > > news:_yxoe.134020$IN.2310899@twister2.libero.it... > > > > > >>Then I think of my small contribution to undersampling as > >>simplifying and clarifying the topic for the practical > >>use, but it > >>should not be underevaluated or ignored or, worse, > >>usurped.
> > > > You aren't alone. There's a lot of good work that was done > > in the 60s and 70s that has been lost and more will be lost > > as engineers from that era retire and die. As in your case, > > the wheel will be re-invented, probably more than once. > > With any luck, global connectivity and vastly improved > > searchable archives will make this phenomenon an artifact of > > a time when knowledge was exploding faster than it could be > > published, catalogued and distributed. > > > > While investigating speech I've "discovered" formants. > I'm currently interested in GPS. I suspect I'm about to "discover" the > ionosphere. > After compensating for ionosphere, I suspect I will "discover" the > troposphere. > > It is very *EDUCATIONAL".
Re-inventing the wheel is great for education or hobbey purposes. But if you are working on a commercial project, your boss would probably prefer you take advantage of other's work as much as possible to save time/money.
Jon Harris wrote:

   ...

> Re-inventing the wheel is great for education or hobbey purposes. But if you > are working on a commercial project, your boss would probably prefer you take > advantage of other's work as much as possible to save time/money.
Sometimes it takes longer to search out what has been done than it does to cobble together a sound solution. It usually took the corporate patent attorneys longer to discover that I had re-invented something than it took me to "invent" it. Jerry -- Engineering is the art of making what you want from things you can get. &#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;
Un bel giorno Richard Owlett digit&#2013265922;:

> While investigating speech I've "discovered" formants. > I'm currently interested in GPS. I suspect I'm about to "discover" the > ionosphere. > After compensating for ionosphere, I suspect I will "discover" the > troposphere.
It may be, but I don't think you are planning to take the credit for these "discoveries". Reinventing the wheel is good in some circumstances; taking other people's work and claiming that is yours, it isn't so good. -- asd
"Jerry Avins" <jya@ieee.org> wrote in message 
news:hYOdnePZgL2-7j7fRVn-pw@rcn.net...
> Jon Harris wrote: > > ... > >> Re-inventing the wheel is great for education or hobbey >> purposes. But if you >> are working on a commercial project, your boss would >> probably prefer you take >> advantage of other's work as much as possible to save >> time/money. > > Sometimes it takes longer to search out what has been done > than it does to cobble together a sound solution. It > usually took the corporate patent attorneys longer to > discover that I had re-invented something than it took me > to "invent" it. >
Someday there may be a web site like Citeseer that catalogs more than just technical papers. It will take a major re-vamping of how we think about intellectual property rights, trade secrets and patents to make it attractive to corporate sponsors. The flip side of publishing is that someone in a Galaxy far, far, away might read what you published, ignore your IP rights and get rich (allowing him to upgrade from a Galaxy to a Continental).
"erine" <erine@hotmail.com> wrote in message
news:_yxoe.134020$IN.2310899@twister2.libero.it...
> Read this astonishing story at > http://spazioscuola.altervista.org/UndersamplingAR/UndersamplingAR.htm > Here it is an excerpt: > A STORY ABOUT UNDERSAMPLING > > by Angelo Ricotta - Rome, Italy > > a.ricotta@isac.cnr.it > > ITALIAN VERSION >
If it aint done in the USA - forget it. Rimmer
"dalai lamah" <antonio12358@hotmail.com> wrote in message
news:y21jlt7yncxf.pcw2x7rrbsvv.dlg@40tude.net...
> Un bel giorno Richard Owlett digit&#2013265922;: > > > While investigating speech I've "discovered" formants. > > I'm currently interested in GPS. I suspect I'm about to "discover" the > > ionosphere. > > After compensating for ionosphere, I suspect I will "discover" the > > troposphere. > > It may be, but I don't think you are planning to take the credit for these > "discoveries". Reinventing the wheel is good in some circumstances; taking > other people's work and claiming that is yours, it isn't so good. > > -- > asd
Shannon himself reinvented the wheel - sampling theory was known way before he appeared. Rimmer