"Andy" <none@none.com> wrote in message news:<5vO_a.81309$Ll4.20032@fe14.atl2.webusenet.com>...> On 14-Aug-2003, PaavoJumppanen@iname.com (Paavo Jumppanen) wrote: > > > If you weren't attempting to make an RTA then you could try the AtSpec > > demo version out as a reference to getting your code running the way > > you expect it to. > > No no, not RTA - in SF it's under "Tools", where it analyzes the current > selection. Ok, basic question: in theory, if I collect the average power of > all components in FFT and plot them - is that my basic spectrum? Are there > any catches to it? I mean, I went over the theory quite a few times, but I > think the practical side has more to it than that. > > Sorry for not providing enough information in the beginning - I guess that > goes to show you that I have little idea about what I am doing :)Well, like I said, you can use AtSpec as another reference then. For that matter, you can download the source code that is responsible for the spectrum analysis as it is part of the AtOne Application Framework (ie. free). As to your question about theory, the common approach is to average periodograms (ie magnitude squared FFT coefficients) together as it seems you already know. This reduces the variance of the power spectrum estimate but it does not remove the bias. The bias of the spectrum estimate is caused by leakage from windowing (unavoidable). The nature of that bias will then depend on what type of window you choose to use. Regards, Paavo Jumppanen Author of AtSpec : A 2 channel PC based FFT spectrum analyzer http://www.taquis.com
Problem: stuck with simple spectral analysis
Started by ●August 13, 2003
Reply by ●August 14, 20032003-08-14
Reply by ●August 14, 20032003-08-14
"Jerry Avins" <jya@ieee.org> wrote in message news:3F3BC5A7.65D29F6F@ieee.org...> Andy wrote: > > > ... > > > everything is a bit more complicated than it should be :-) > > > In home repair, that's called "The Mushroom Effect". Under different > aliases, it's universal.Jerry, Good one! Fred
Reply by ●August 14, 20032003-08-14
"Fred Marshall" <fmarshallx@remove_the_x.acm.org> wrote in message news:<RgO_a.3989$Jk5.3709982@feed2.centurytel.net>...> It's a quest to keep things simple / understandable to the least > sophisticated audience. I get a great kick out of helping folks "get it".Yeah, Fred... that's pretty obvious from your posts. You have a very rare gift in that your writing conveys your enthusiasm so clearly. While I get that sort of kicks too, most of the time they come when I talk to colleagues and students face to face... actually, that's the most fun part of the job. Some colleague comes in to my office and sits down and discusses some sort of problem or question over a cup of coffe. Most of the time it's only venting frustration, but every once in a while the discussion takes a "good" turn in that some idea pops up, that may be helpful to pursue. I really like working with students in that manner. My challenge is to find a useful explanation to whatever they ask about. You can literally see how their minds work over the problem, their confusion when they walk out the door... the next time they come back, they have worked the problem over and have their own explanation of what's going on. Some times I make an adjustment, point out something they have missed or redirect their focus from an insignificant detail... and before I understand what's going on, a couple of weeks later I am all of a sudden left wondering what the student meant, and find that I have learned something new from the dicussion. Yep, that's the good part about the job. Seeing the effect on people when they solve a difficult problem or learn a difficult trick, how they slowly and steadily become more and more confident in what they do. Seeing the expression on their faces change literally as they think the problem through and grasp the solution, before they formulate the solution in their own words. Unfortunately, I don't see the close-ups of those kinds of things very often, but when I do, it's what makes the job worth the effort. Rune
Reply by ●August 15, 20032003-08-15
"Rune Allnor" <allnor@tele.ntnu.no> wrote in message news:f56893ae.0308141635.47768de4@posting.google.com...> "Fred Marshall" <fmarshallx@remove_the_x.acm.org> wrote in messagenews:<RgO_a.3989$Jk5.3709982@feed2.centurytel.net>...> > > It's a quest to keep things simple / understandable to the least > > sophisticated audience. I get a great kick out of helping folks "getit".> > Yeah, Fred... that's pretty obvious from your posts. You have a very > rare > gift in that your writing conveys your enthusiasm so clearly. > > While I get that sort of kicks too, most of the time they come when I > talk > to colleagues and students face to face...Thanks Rune! Well, you're certainly one of the stalwarts here yourself! I especially appreciate having someone here to talk with about underwater stuff now and then! Fred
Reply by ●August 15, 20032003-08-15
Fred Marshall wrote:> > "Rune Allnor" <allnor@tele.ntnu.no> wrote in message > news:f56893ae.0308141635.47768de4@posting.google.com... > > "Fred Marshall" <fmarshallx@remove_the_x.acm.org> wrote in message > news:<RgO_a.3989$Jk5.3709982@feed2.centurytel.net>... > > > > > It's a quest to keep things simple / understandable to the least > > > sophisticated audience. I get a great kick out of helping folks "get > it". > > > > Yeah, Fred... that's pretty obvious from your posts. You have a very > > rare > > gift in that your writing conveys your enthusiasm so clearly. > > > > While I get that sort of kicks too, most of the time they come when I > > talk > > to colleagues and students face to face... > > Thanks Rune! Well, you're certainly one of the stalwarts here yourself! > I especially appreciate having someone here to talk with about underwater > stuff now and then! > > FredIgnoring that three's a crowd, I'll join on the admiring side of your mutual admiration society. It's a pleasure to eavesdrop on the way you two -- I don't mean to exclude others by omission -- patiently get tough ideas across and dispel confusion. I learn not only from what you do, but from how you do it. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●August 15, 20032003-08-15
"Jerry Avins" <jya@ieee.org> wrote in message news:3F3D13B4.EA5FF474@ieee.org...> Fred Marshall wrote: > > > > "Rune Allnor" <allnor@tele.ntnu.no> wrote in message > > news:f56893ae.0308141635.47768de4@posting.google.com... > > > "Fred Marshall" <fmarshallx@remove_the_x.acm.org> wrote in message > > news:<RgO_a.3989$Jk5.3709982@feed2.centurytel.net>... > > > > > > > It's a quest to keep things simple / understandable to the least > > > > sophisticated audience. I get a great kick out of helping folks"get> > it". > > > > > > Yeah, Fred... that's pretty obvious from your posts. You have a very > > > rare > > > gift in that your writing conveys your enthusiasm so clearly. > > > > > > While I get that sort of kicks too, most of the time they come when I > > > talk > > > to colleagues and students face to face... > > > > Thanks Rune! Well, you're certainly one of the stalwarts here yourself! > > I especially appreciate having someone here to talk with aboutunderwater> > stuff now and then! > > > > Fred > > Ignoring that three's a crowd, I'll join on the admiring side of your > mutual admiration society. It's a pleasure to eavesdrop on the way you > two -- I don't mean to exclude others by omission -- patiently get tough > ideas across and dispel confusion. I learn not only from what you do, > but from how you do it.Jerry, Wow! Thanks Jerry! No need to mention the "kudos to Jerry" thread that's current!! I don't know if this helps or not but .. I once made acquaintance with an American Prof. of the Sorbonne. He asked me if I'd read Kurt Vonnegut, Jr. At the time I had to say "no". He recommended Vonnegut in response saying: "he dares to be light". I liked the picture and once I "got it", have figured if we don't take ourselves too seriously then we can "dare to be light" and take the risk of being wrong now and then. As long as we're not often misleading, then we can stretch and that's fun! There's an exercise in management schools that you may have seen. You're given a "plane crash in the desert" scenario to be in and a list of items at your disposal to survive / get back home. The exercise is done in two parts: Part 1, you decide all by yourself what to do with what you have. Then you turn this in to the facilitator. Part 2, you form up in groups of 6 or so people and solve the problem all over again. Then you turn in the joint result. (The facilitators have the "right answer"). Almost invariably, the groups do better than the individuals. This is to make the point that "two (or N) heads are better than one" and that diverse views and experiences usually contribute best to solving problems. So, I know we don't always see things the same way - and that becomes a group strength. So, we value the other's contributions even though we sometimes disagree or have a very different perspective. I seem to recall a fairly recent discussion about linear time-varying systems. That's one where I learned a bit in the process about multiplier inputs.... Fred
Reply by ●August 15, 20032003-08-15
Jerry Avins <jya@ieee.org> wrote in message news:<3F3D13B4.EA5FF474@ieee.org>...> It's a pleasure to eavesdrop on the way you > two -- I don't mean to exclude others by omission -- patiently get tough > ideas across and dispel confusion. I learn not only from what you do, > but from how you do it.Eh... for some reason I think that people easily could do infinitely better than following my example in what I do and the way I do things... Of course, having said that, an important part of learning is to learn from other people's mistakes; not only form their successes. Rune
