From picone at ece.msstate.edu Thu Mar 5 12:09:11 2009 From: picone at ece.msstate.edu (Joseph Picone) Date: Thu Mar 5 12:09:41 2009 Subject: [ece3163] laser turntables Message-ID: <49B01547.2060007@ece.msstate.edu> We have briefly discussed analog vs. digital issues in audio. On page 24 of the March issue of IEEE Spectrum, there is a short article on a laser turntable. The product discussed can be found here: http://www.elpj.com/ An interesting piece of retro technology ;) -Joe From picone at ece.msstate.edu Wed Mar 11 08:37:59 2009 From: picone at ece.msstate.edu (Joseph Picone) Date: Wed Mar 11 08:38:08 2009 Subject: [ece3163] a new generation of baseball cards Message-ID: <49B7BEB7.5030508@ece.msstate.edu> I thought this was interesting: http://www.nytimes.com/2009/03/09/technology/09topps.html?ref=technology High quality computer graphics makes use of many of the concepts we discuss in this class. -Joe From picone at ece.msstate.edu Sat Mar 14 11:11:26 2009 From: picone at ece.msstate.edu (Joseph Picone) Date: Sat Mar 14 11:11:57 2009 Subject: [ece3163] plasma speakers Message-ID: <49BBD72E.8050602@ece.msstate.edu> From the "what will they think of next" file: http://en.wikipedia.org/wiki/Plasma_arc_loudspeaker Since we have some audio experts in class this semester, I thought I would pass this along. Some military weapons are being designed that utilize this concept: http://blog.wired.com/defense/2009/03/army-turns-bomb.html Enjoy, -Joe From picone at ece.msstate.edu Sun Mar 15 06:34:09 2009 From: picone at ece.msstate.edu (Joseph Picone) Date: Sun Mar 15 06:34:42 2009 Subject: [ece3163] exam no. 2 results Message-ID: <49BCE7B1.1030408@ece.msstate.edu> The results for exam no. 2 were somewhat disappointing and are attached below. I think many of you simply did not spend enough time studying over the past five weeks. Remember, reading the book and working all the homework problems are extremely important, and it takes time for this material to sink in. As I have mentioned several times, simply copying the online solutions will not guarantee a good score on the exam, because these solutions leave out a lot of details. This was particularly true for two problems on this exam (4.6(a) and 5.45(c)). Problem 5.45(c) was more challenging than you might have thought. The solution skipped a large number of steps and wrote an equation that few of you probably understand. Hence, in an effort to help you improve your score, I am offering 20 points of extra credit for those who provide a detailed solution to that problem before 8 AM on March 27. Your solution must include: (1) A theoretical solution using any method available to you. For example, you might want to try to solve the problem using z-transforms. (2) A verification of that solution using MATLAB. Again, you can do this numerically and/or symbolically. (3) A detailed electronic document in either MS Word or PowerPoint describing your solution. I'll give an extra 5 points (for a total of 25) to anyone who turns in a correct solution before 9 AM on March 24. Solutions will not be accepted before that since technically we are on Spring Break. If no one has a solution by then, I'll award the 5 points to the first person who turns in a correct and sufficiently detailed solution. You are allowed to work in groups on understanding the solution, but the ultimate electronic document must be your original work. I do not expect any two documents to look very similar, since each of you has your own unique writing style. Email me if you want to know your grade on the exam. Good luck, -Joe ====================== E1 E2 Avg 67 50 Median 68 56 Stdev 21 21 Min 23 3 Max 100 78 Histogram: < 10 0 2 10-19 0 2 20-29 3 0 30-39 2 1 40-49 0 4 50-59 3 7 60-69 6 6 70-79 5 2 80-89 4 0 > 90 4 0 Total: 27 24 From picone at ece.msstate.edu Sat Mar 21 17:31:13 2009 From: picone at ece.msstate.edu (Joseph Picone) Date: Sat Mar 21 17:31:35 2009 Subject: [ece3163] working exam problems in Signals and Systems Message-ID: <49C56AB1.6040907@ece.msstate.edu> Tao and I were talking this afternoon about the challenges of learning this material and the difficulty students have in working problems. We are both concerned that students don't understand the difference between understanding how to work the homework problems... and the solutions provided by the author. For example, consider the second problem on the exam - prob. 5.45b. In general terms, this problem asked "Given a linear system described by a difference equation (provided), and given an input (provided), compute the output." Now, the solution provided by the author wrote an equation that represented a very non-obvious way to solve the problem (using a trick you could say). Then it turned out that this solution was wrong. Therefore, this was a very bad model to use to understand this problem. Yet, most of you simply copied the solution from the solution's manual onto the exam, which did not get you a lot of credit. Instead, had you stepped back and thought about this problem, you probably could have written: (1) Find the impulse response (which was part(a)). (2) Convolve that with the input. or, even a more direct approach: (1) Plug the input into the difference equation. (2) Use a numerical solution to find the output. Then there is a frequency domain method: (1) Compute the transform of the impulse response. (2) Compute the transform of the input. (3) Multiply. (4) Compute the inverse transform. Finally, there is an approach involving insight, noting that the input signal is the combination of a DC signal and two sinewaves. The output for the DC value can be computed directly using the difference equation. The output for the sinewaves can be computed by evaluating the system's frequency response at the frequencies of each sinewave. We have discussed many of these approaches in class many times, and I know most of you would agree the first three are pretty straightforward. Just writing out one of these explanations would have probably gotten you between 10 to 15 points (out of 20) on that problem because it demonstrated that, given enough time and MATLAB, you could have found a brute force solution to the problem. Further, when working the homework problems at home each week, you should be working the problems using both analytic and numerical techniques (with MATLAB) and comparing the results. Only after seeing both approaches converge to the same solution will you gain mastery of this material. At this point you might say that is too much work. But if you think about it, today you can work these homework problems much faster than in the "olden days." This is because you can use MATLAB to automate a lot of routine things such as partial fractions expansions, symbolic integration, polynomial factorization, plotting, etc. As I stated at the beginning of class, mastering this material is not possible without studying the material on an incremental basis outside of class and outside of the recitation section. You need to read the book before the lecture, attend the lecture, work the homework, go to recitation with questions on the homework and lectures in hand, re-read the book after the recitation class, and then ask more questions. Cramming before an exam simply will not work because there is no time for the material to sink in. Having said all this, you also have ample opportunity to augment your grade with special extra credit problems, but that is an option that is best only for those of you who have ample amounts of time. If you are taking a large number of hours, or working part-time in addition to carrying a full load, you are probably going to have a hard time finding the time to work extra credit problems. -Joe From tm334 at ece.msstate.edu Wed Mar 25 12:04:25 2009 From: tm334 at ece.msstate.edu (Tao Ma) Date: Wed Mar 25 12:04:32 2009 Subject: [ece3163] Monday Recitation change to Tuesday (just for next week) Message-ID: <49CA6419.4000507@ece.msstate.edu> For some personal reason, I need move Monday(march 30) recitation to Tuesday(march 31) in next week. Time and place are still the same. This schedule change is ONLY for next week. Thanks! -Tao From picone at ece.msstate.edu Thu Mar 26 15:07:59 2009 From: picone at ece.msstate.edu (Joseph Picone) Date: Thu Mar 26 15:09:02 2009 Subject: [ece3163] extra credit problem Message-ID: <49CBE09F.3020105@ece.msstate.edu> Since a number of you have asked... To turn in the extra credit problem, please just email your solutions to me as either Word, pdf, or ppt documents. -Joe From picone at ece.msstate.edu Sun Mar 29 14:52:47 2009 From: picone at ece.msstate.edu (Joseph Picone) Date: Sun Mar 29 14:53:28 2009 Subject: [ece3163] third exam Message-ID: <49CFD18F.9090401@ece.msstate.edu> I realize a number of you had a lot of exams at the time we gave the second exam. So, to avoid this for the third exam, I would like you to work with Tao this week in the recitation class to decide on a new time for the third exam. Choose a time that has as few conflicts with your other major activities as possible. I'll adjust the material covered on the exam accordingly. Just let me know by the end of Thurs. what the new date is. The current scheduled date is Wednesday, April 22, 2009. -Joe From picone at ece.msstate.edu Sun Mar 29 15:53:44 2009 From: picone at ece.msstate.edu (Joseph Picone) Date: Sun Mar 29 15:54:19 2009 Subject: [ece3163] RLC Extra Credit In-Reply-To: <1238357268.49cfd51477880@webmail.msstate.edu> References: <49CFD18F.9090401@ece.msstate.edu> <1238357268.49cfd51477880@webmail.msstate.edu> Message-ID: <49CFDFD8.6010308@ece.msstate.edu> > What exactly are you looking for on the new RLC extra credit? Should we just > show a simulation of output voltage and current as a function of time for all > reasonable frequencies(Vin=1V)? For the circuit, consider a system that consists of a 1V sinewave input with the series RLC circuit connect to the voltage source (as shown in class). The output is the voltage across the capacitor. I hope all students now understand that the output voltage is a sinewave at the same frequency as the input, but with a different amplitude and phase. Why? The question you must answer for extra credit is: For some value of the frequency of the sinewave, and for some combination of RLC values, can the output voltage have an amplitude greater than 1V? I will accept any form of a proof as long as it is convincing and not just hand-waving :) You can prove this analytically, numerically, etc. But you must supply a convincing argument in either an MS Word, pdf, or ppt file. As I cautioned in class, you can ask anyone for help, but you must convince me with your explanation, and your explanation can't simply be "because Dr. Winton says so!". -Joe From picone at ece.msstate.edu Sun Mar 29 18:02:54 2009 From: picone at ece.msstate.edu (Joseph Picone) Date: Sun Mar 29 18:03:55 2009 Subject: [ece3163] extra credit exam problem Message-ID: <49CFFE1E.3030304@ece.msstate.edu> I have graded your extra credit exam problems and am uploading your solutions to the exam directory on the web site. Please review those and compare your results with your colleagues. -Joe From picone at ece.msstate.edu Mon Mar 30 21:27:18 2009 From: picone at ece.msstate.edu (Joseph Picone) Date: Mon Mar 30 21:27:33 2009 Subject: [ece3163] The Seattle Fault Message-ID: <49D17F86.1020704@ece.msstate.edu> As I mentioned in class today: Here is a little bit about the fault line that runs along the Pacific Northwest coast and the impact of a tsunami: http://www.seattlepi.com/local/211158_tsunamiseattle08.html What is scary is that scientists are predicting this will happen sooner or later. However, the mean time between these things is either 1,000 years or 500 years depending on who you believe, and it is hard to accurately predict such things on such minimal data. The report I was listening to was discussing the possibility of a 9.0 earthquake, which they said would have a much more devastating impact than a 7.0 earthquake due to the nature and duration of the vibrations (which is what we were discussing in class). Here is a little more on the fault line itself: http://en.wikipedia.org/wiki/Seattle_Fault http://www.djc.com/special/design99/10060788.htm Enjoy, -Joe