Path: csiph.com!usenet.blueworldhosting.com!feeder01.blueworldhosting.com!newsfeed.fsmpi.rwth-aachen.de!newsfeed.straub-nv.de!news-1.dfn.de!news.dfn.de!news.informatik.hu-berlin.de!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: vallor Newsgroups: alt.usenet.kooks,sci.physics Subject: DFTs Date: 8 Mar 2016 10:24:12 GMT Lines: 84 Message-ID: References: <28189e9d-b2ff-46d5-b481-1d26a1d37491@googlegroups.com> <910a3b6c3baf6ecfefb6505162b5393c@dizum.com> <0rhodbdife2fovihlmgrt2freplvebv5su@4ax.com> <1mjs89z.xh5k4dcsx517N%snipeco.2@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Trace: individual.net bsHSNdaRcDHnT87daMGpiw4WQPHNqi1/1F3NALtU0wvN3w5ZmR Cancel-Lock: sha1:lrBWCwMGUvfQ0Q0/hVFE5iaE+9A= X-Face: $FV2_=&Q|WB`]oRnO!CA~)A9di!0[Gwr1lw!1E`1kB snipeco.2@gmail.com (Sn!pe) wrote: > >> "Fakey's" dogwhistle holder living at 5907 Stanton Ave., Pittsburgh, PA >> (aka Teh Mop Jockey), socked up as 5907 Stanton Avenue, Pittsburgh, PA >> 15206-2117 wrote: >> >> [...] >> >> > >> the difference between peak and RMS values, >> > > >> > > Oh, I know the difference, in fact, I proved it *and* used the >> > > Euler-Fourier Formula to derive RMS L-N voltage >> > >> > the fuck? you didn't derive anything. you took the RMS value and, for >> > some reason, factored it into a sine wave plot like a complete idiot noob >> > would. >> > >> > > from peak L-N voltage, >> > > then used the same equation to derive RMS L-L voltage from that RMS >> > > L-N voltage... something none of you morons have been able to >> > > accomplish. >> > >> > funny. you never bothered to show us the exact full equations that you >> > graphed, for some reason. >> > >> > > Aren't you the moron who k'lamed that RMS voltage doesn't fluctuate, >> > > and is thus DC? Yeah... yeah you are. >> > >> > RMS is a power average estimate, not a sine wave. >> >> [...] >> >> PMFJI >> >> It's apparent that Fakey just doesn't comprehend the meaning >> of Root Mean Square or why we use it. Let me see if I can explain >> it to him in simple terms: >> >> Because an AC power voltage waveform normally swings from negative >> to positive and back equally either side of zero, its simple mean >> is zero. Such a result is of use to neither man nor aspiring >> electrical engineering pundit. >> >> So: square the waveform. The squared positive half of each cycle >> is still positive but the negative half, when squared, becomes >> positive too. -1 multiplied by -1 equals +1, remember? >> >> Now take the mean of the squared waveform -- this will now be a >> positive quantity. Because you've squared everything you now have >> to "unsquare" it again; take the root of that mean and you have RMS. >> >> It's a \\mean\\ value, \\not\\ a waveform; root MEAN square, geddit? >> >> >> HTH HAND HORSE > > Good explanation. And the other reason for calculating RMS > is that it works in Ohm's law for power, ie, > > P = voltage(RMS) * current(RMS) * cos(phase angle between > them) > > Even Fakey could understand, if he tried. He will try ever > so hard not to, and bleat that you think RMS is DC (which is > closer to truth than his limited understanding is). I never did understand why he was talking about Fourier transforms in our discussions -- the DFT moves one from the time domain to the frequency domain. (Think: bumping your tunes with a spectrum analyzer display.) But that was what he started with in the first place. Maybe he meant an inverse Fourier transform, to compose his waveform from the discrete signals he gave with his inputs? I don't think that will work how he expects it too, assuming that's the idea. -- -v