quarterwave

9 ms·

31.
by quarterwave 12y ago
For anyone interested, here's the essence of a phase-locked loop: Say you're climbing up a long staircase and the step height increases suddenly - then you'll bump into the next step. If the height were to go the other way i.
32.
by quarterwave 12y ago
Nice demo! Quick back of the envelope calculation for the current to overcome dynamic friction: I = mu_friction * Mass * grav_acc / (Turns_per_length * Area * Br_magnet) Say Mass=0.1kg, coil at 600 turns per metre, hand-wave mu_frictio
33.
by quarterwave 12y ago
You're right, and your explanation helped me understand the article better when I read it again. Thanks.
34.
by quarterwave 12y ago
For real-time updates in response to user actions , which is a bigger concern: average latency, or its variance? Example: Server generates a sine wave which gets displayed as a rolling chart waveform on the client. As client spins a knob t
35.
by quarterwave 12y ago
I once used the Basic Stamp in a product prototype - a fairly sophisticated piece of instrumentation. I initially chose the Basic Stamp (iirc it had a Ubicom chip) for its totally rock solid RS-232. Eventually I realized that the Basic Stam
36.
by quarterwave 12y ago
One way to understand limits is compound interest. Start with a dollar, compound 100% in year to get $2. Halving the interest rate and compounding twice gives $2.25. The "limit" of this less-interest-more-often process, ad infinit
37.
by quarterwave 12y ago
I first encountered this wonderful quote in the foreword to one of the editions of the Feynman Lectures, the foreword in this case being written by an awesome physics professor in my college (V.Balakrishnan a.k.a Balki): "... the comb
38.
by quarterwave 12y ago
Is an image hash a very different beast from the hashing function used in passwords etc? In the latter we want large sensitivity to small changes, while in an image hash we want a measure sensitive to similarities. Naively I'd expect i
39.
by quarterwave 12y ago
Saw this after posting my comment. I agree this is the simplest way to think of an FFT.
40.
by quarterwave 12y ago
Think of FFT like music notation - a separation into notes, dynamics, and tempo. Alexander Graham Bell came up with the idea of increasing the capacity of telegraph lines by combining several 'dit-da-dit' streams at different pitc
41.
by quarterwave 12y ago
This is superb stuff, e.g; phase change at hard/soft boundaries is explained nicely. EE's may recognize the conformal map leading to the Smith chart; since EM waves are E+M we can have both 'open-circuit' and 'short
42.
by quarterwave 12y ago
Course is classroom format. i will post the assignment on github.
43.
by quarterwave 12y ago
Well put. A 'predictive model' should say 'if you do X then you will end up with Y' - and the X cannot be adjusting some number. The X has to be stuff like 'building ETU's in West Africa', or 'canceli
44.
by quarterwave 12y ago
In south Indian classical (Carnatic) music the greatest modern composer is Tyagaraja (1767-1847), who interestingly was a contemporary of Beethoven. Tyagaraja was prolific in a form of composition called a kriti , at once both structured a
45.
by quarterwave 12y ago
One person who should also have got the Nobel prize for pioneering work on III-V LED's is Nick Holonyak. http://en.wikipedia.org/wiki/Nick_Holonyak
46.
Semiconductor scaling and concurrent clouds(keyfunda.com)
9 points by quarterwave 12y ago|0 comments
47.
by quarterwave 12y ago
I searched for R_0 data on flu pandemics and found this: http://www.ecdc.europa.eu/en/healthtopics/documents/0905_pan... Note the sharp jump as R_0 goes from sub-2 to over-2, which should not be surprising (h
48.
by quarterwave 12y ago
Anyone dealing with antennas and noise should read the classic 1946 paper by Dicke: http://www.eng.yale.edu/rslab/internal/Papers/dickepaper.pdf tl, dr: One puzzler is that antenna radiation is frequency depe
49.
by quarterwave 12y ago
Tony: Umm... Control? Control: Yes, Tony? Tony: If I may ask, how did you determine this sum of a 150,000 pounds a day? Control: A very good question, Tony. You see, I simply took the figure that our American cousins have calculated u
50.
by quarterwave 12y ago
http://en.wikipedia.org/wiki/1918_flu_pandemic mentions two theories why the 1918 flu pandemic ended (see section 'End of the pandemic'). I'm trying to understand the mutation theory. How come there is n
51.
by quarterwave 12y ago
Thanks for posting this link, I now begin to understand what Shakespeare meant by 'spangled starlight sheen' [A Midsummer Night's Dream].
52.
by quarterwave 12y ago
Looks like a binary star, similar to the two suns of Tatooine. http://en.wikipedia.org/wiki/Binary_star#mediaviewer/File:Or... OP: This is an amazing tool to learn the sensitivity of dynamical systems to initial c
53.
by quarterwave 12y ago
This is a beautiful post, and I am reluctant to try and say anything profound. Still, all of HN's a stage so I'll attempt a brief explanation for the general reader about why we need voltage regulators. A logic chip like a micropr
54.
by quarterwave 12y ago
Years ago in college, for the toughest course I'd carefully pick an advanced textbook - something one or two levels ahead of the current one - and soak myself in that. Example: for an introductory quantum mechanics course I read Dirac&
55.
by quarterwave 12y ago
Clearly not a book for the ordinary reader. For me the transition from Sec.1.1 to Sec.1.2 was akin to starting with a quiet walk in the park, and then suddenly finding oneself clinging to a rock face as a cloud of chalk dust drifts down fro
56.
by quarterwave 12y ago
In my humble opinion, the key is to judge oneself accurately. Or get someone to do so. Ramanujan wrote to Hardy: "I am already a half starving man. To preserve my brains I want food and this is my first consideration. Any sympathetic l
57.
by quarterwave 12y ago
"Photon number is conjugate to phase' - I'd like to understand that better, is it the same as saying photon counting destroys phase information? Would it also hold true for gated counting?
58.
by quarterwave 12y ago
Is 'frequency' 1d or 2d? Also, gain transfer function looks like a spline, why not try an FIR? It would cool to add a few images with periodicity. I expected the lake bed image to show some quasi-periodic lines, but couldn't
59.
by quarterwave 12y ago
Well written, tallies with my start-up experiences.
60.
by quarterwave 12y ago
Albert Einstein said of Mahatma Gandhi: "Generations to come, it may well be, will scarce believe that such a man as this one ever in flesh and blood walked upon this Earth." When we were in school our class was taken to see the f

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