Why is DSP considered the hardest subject to study at school?
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From: Joerg on 9 Jul 2010 12:15 Jerry Avins wrote: > On 7/9/2010 5:14 AM, Rune Allnor wrote: >> On 9 Jul, 07:40, Le Chaud Lapin<jaibudu...(a)gmail.com> wrote: >>> >>> 1. Every person who considers himself/herself to be scientist/engineer >>> should take responsibility for the domain, depth, and breadth of what >>> s/he learns. Learning slowly is OK. The end-result is worth the >>> effort. >> >> One of the few professors I know (the only one?) who I consider >> worthy of his credentials once said something like "true insight >> in a handful of well-chosen subjects beat vast amounts of superficial >> knowledge hands down." >> >> I couldn't agree more. > > I agree, but not completely. As a generalist, I have solved practical > problems that stumped colleagues more expert than I. My applying what > seemed to them unrelated techniques and ideas had them asking "Why > didn't I think of that?" > Yes. Many of us have to venture into very far-off turf. For example, for me that is often dynamic load changes and stresses on an electronics module, engine behavior, foresee what-ifs in the end user marketplace and so on. Without being a generalist I could not do my job. [...] -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Tim Wescott on 9 Jul 2010 15:03 On 07/08/2010 09:17 PM, steveu wrote: >> On 07/08/2010 02:26 PM, Nasser M. Abbasi wrote: >>> On 7/8/2010 2:07 PM, HardySpicer wrote: >>> >>>> ahhh diddums...you should try some advanced control engineering and >>>> see how you get on. >>>> No sympathy. >>>> >>>> Hardy >>> >>> But DSP and control in a way are interrelated? >>> >>> A filter is just a system. IIR has feedback. Feedback is used in DSP. >>> Using Costas loop (phase-locked loop) in demodulation sues feedback > loop >>> to detect carrier frequency, and I am sure there many other examples. >>> >>> Matlab uses state space approach in converting analog filter to digital >>> filter. Modern control theory is all state space. >>> >>> For me, control/ linear system theory/ signal processing are all very >>> much interrelated. Advanced control theory goes a little more crazy > with >>> advanced math and matrix theory than DSP, but at the end of the day, it >>> is all just a system, with input/output and feedback and fancy >>> disturbances thrown in to make it real. >>> >>> I love to study control theory also, and I also found it very hard. I >>> think control engineers and DSP engineers have the same genetics. >> >> Real control (forget theory) is about attempting to fit some tractable >> mathematical model to a plant that is -- at root -- viciously nonlinear >> with unknowable dynamics. Many control engineers are so used to doing >> this that they don't even consciously do so -- they use integrator >> anti-windup because "things won't work if I don't", they use >> conservative plant models, etc., -- because at root, it's a nasty, nasty >> problem to solve. > > Isn't a more common case that the plant is pretty well known, and pretty > well linear, but only over a certain range. The tricky stuff is typically > ensuring things don't do wacky if you step outside the well characterised > areas. Yes and no. It's pretty common that what you pretend you know about the plant (or what you confidently think you know about the plant, if you're not paying attention) is clear and indicates that the plant is linear over some range that you have a pretty good grasp of. What you really don't know is the details of the plant behavior beyond the first couple of poles, and maybe a resonance or two -- when was the last time you successfully made a controller work with two differentiators? Three? What about dealing with bearing friction -- given a plant with sticky bearings, can you say "sure, there's a control rule for that", or do you adopt a grave expression and say "I'm sorry, you'll just have to flog the mechanical guys through another iteration of the design; what you have here just can't be controlled to the precision you want". Those problems (and more -- how about gain or damping changes with temperature!) all -- I contend -- fit my statement that it's a nasty problem to solve. We've just learned by experience to label some parts of the problem space as "clear sailing" and some parts as "here be dragons". -- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" was written for you. See details at http://www.wescottdesign.com/actfes/actfes.html
From: Jerry Avins on 10 Jul 2010 01:46 On 7/8/2010 9:42 PM, Fred Marshall wrote: ... > School was about linear systems - Laplace transforms and I think Z > transforms were self-taught. But I have never been to drawn into the > math - in my view the math follows the situation. If it's a necessity > then fine - but much is to be understood with cartoons really. I learned > that method in an RCA lecture series on DSP. It's just a variation on > the "graphical convolution" method - which is something worth > understanding. I'm not sure what you mean by cartoons. (I know what Feynman meant.) I learned to place great store by graphical solutions as grounding and illustration of math. I had an early AC Circuits course taught by an instructor named Lieljestrand at RCA Institutes. He was a whiz at analyzing circuits using phasor diagrams that he drew on the blackboard. His classroom performance would have been outstanding had he been sighted. It was absolutely remarkable considering that he was stone blind. Examples of a picture being worth a thousand words (or a hundred equations) are the conversion of low-percentage-modulation AM to NBFM by a quadrature shift of the carrier's phase relative to the sidebands, and the junction of a R and C across the ends of a transformer's grounded-centertap secondary providing an output whose phase is variable over a 180 degree range by varying the resistor. Lieljestrand's blindness taught me to do analysis by visualizing these diagrams -- you call them cartoons? -- without actually drawing them. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
From: Rune Allnor on 10 Jul 2010 04:12 On 10 Jul, 07:46, Jerry Avins <j...(a)ieee.org> wrote: > Lieljestrand's blindness taught me to do analysis by visualizing these > diagrams -- you call them cartoons? -- without actually drawing them. I think that's the key for learning anything: Being able to start from a sylized sketch that contains the essentials, and expand from there. Like looking at a chess board and internally visualizing a battle scene as from Lord of the Rings. I the '70s one of the great astronomical communicators, Carl Sagan, had his 12-13 episode show Cosmos, that might have been simple, by today's standards on special effects, but that had me totally stunned. I supect (I haven't seen the show since it first ran in the late '70s) that the 'primitive' graphics effects were good enough to give the general idea, but crude enough to allow viewer's imagination to fill in its part. Soon afterwards - I don't know if it was a spin-off from Sagan's show or mere opportunistic coincidence - a book 'Cosmos' was published. I remember sitting for hours in the school library reading about stars, protoplanetary disks, black holes, the Herzpung-Russel classification of stars - and trying to visualize all of that in my mind. For the past decade or so, a number of cable TV channels have started producing shows on astronomical subjects. Stunning as the computer graphics in these programs is, I find them totally boring. There is nothing left for me to figure out or imagine. Those things have degenerated to mere show-off pieces for computer graphics artists. Or standard as the graphics seems to be - computer graphics *engineers*. Nah, the real effort has to take place inside the student's mind. As somebody once said "I can't teach you, but I can help you learn." Rune
From: Jerry Avins on 10 Jul 2010 10:27
On 7/10/2010 4:12 AM, Rune Allnor wrote: ... > For the past decade or so, a number of cable TV channels have > started producing shows on astronomical subjects. Stunning as the > computer graphics in these programs is, I find them totally boring. > There is nothing left for me to figure out or imagine. Those things > have degenerated to mere show-off pieces for computer graphics > artists. Or standard as the graphics seems to be - computer graphics > *engineers*. > > Nah, the real effort has to take place inside the student's mind. > As somebody once said "I can't teach you, but I can help you learn." I often, not always, prefer to read a book than see a movie made from it. Visualization is a powerful tool. Once, in a meeting, I gave an approximate (10%) numeric solution to transcendental equation that had just become germane. I simply visualized my slide rule. Visualizing a calculator doesn't work for me. :-) Jerry -- Engineering is the art of making what you want from things you can get. ����������������������������������������������������������������������� |