Interpolation response overshoot, why?
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From: Jerry Avins on 7 Jan 2010 15:13 Jim wrote: > > Jerry Avins wrote: >> jim wrote: >> >> ... >> >>> it didn't sound like he was asking about reconstruction. He asked about >>> interpolating without overshoot. >> Interpolating is sort of partial reconstruction. If you interpolate the >> signal 0, 1, 1, 0, -1, -1, ... by two, you get 0, .577, 1, 1.55, 1, 577, >> 0. -.577, -1, -1.55, -1, -.577, .... >> > > > Surely you can't be claiming that is the only possible way to > interpolate that sequence. > > What about linear interpolation? That would produce no overshoot. And > the reason is the filter [1/2 1/2] has unity gain at DC and no negative > terms. Any other filter that is also so constrained can be used for > interpolation without any overshoot. That's not the only way to interpolate it, but it is some of the points that would appear in a reconstruction. In general, a good interpolation has that characteristic. Jerry -- Engineering is the art of making what you want from things you can get. ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
From: pnachtwey on 7 Jan 2010 20:03 On Jan 5, 10:55 pm, "Laron" <jason.pi...(a)inbox.com> wrote: > Hi, > When simulate the FIR filter response, run interp(Matrix,n) in matlab, > the maximum of Matrix is 1,but the response is larger than 1? > I wonder know why this could be happen and how to degrade this > effect? > > B. R. > Thanks. You can use a Nth order polynomial to interpolate between points. A 3rd order polynomial will do or even a 3rd order cubic spline but the trick it to ensure the derivative at the peaks is 0. Easy. Peter Nachtwey
From: JCH on 9 Jan 2010 04:55 "Laron" <jason.piker(a)inbox.com> schrieb im Newsbeitrag news:BOednfutGppmrtnWnZ2dnUVZ_uWdnZ2d(a)giganews.com... > Hi, > When simulate the FIR filter response, run interp(Matrix,n) in matlab, > the maximum of Matrix is 1,but the response is larger than 1? > I wonder know why this could be happen and how to degrade this > effect? You possibly have an ODE (system) of 2nd degree: See Page 1 * http://home.arcor.de/janch/janch/_control/20100109-overshooting/ 0,0001 u'' + 0,01 u' + u = w See Page 2: Degrading using higher damping 0,0001 u'' + 0,018 u' + u = w -- Regards JCH
From: pnachtwey on 10 Jan 2010 01:41 On Jan 9, 1:55 am, "JCH" <ja...(a)nospam.arcornews.de> wrote: > "Laron" <jason.pi...(a)inbox.com> schrieb im Newsbeitragnews:BOednfutGppmrtnWnZ2dnUVZ_uWdnZ2d(a)giganews.com... > > > Hi, > > When simulate the FIR filter response, run interp(Matrix,n) in matlab, > > the maximum of Matrix is 1,but the response is larger than 1? > > I wonder know why this could be happen and how to degrade this > > effect? > > You possibly have an ODE (system) of 2nd degree: > > See Page 1 > *http://home.arcor.de/janch/janch/_control/20100109-overshooting/ > 0,0001 u'' + 0,01 u' + u = w > > See Page 2: Degrading using higher damping > 0,0001 u'' + 0,018 u' + u = w > > -- > Regards JCH This has nothing to do with the original question. Laron wants to know how to INTERPOLATE without OVERSHOOTING. Peter Nachtwey
From: pnachtwey on 10 Jan 2010 01:42
On Jan 6, 4:41 pm, jim <"sjedgingN0Sp"@m(a)mwt,net> wrote: > Laron wrote: > > > I just know there would be a lpf, not quite sure about the reconstruction > > process. > > I got an idea that the overshoot caused from the lpf, but the detail "how" > > is still not clear. > > A low pass filter with only positive values and a DC gain of 1 will > guarantee no overshoot. > > -jim But that is not interpolating. Peter Nachtwey |