Not a member?

# Discussion Groups > Invariance

Comp.dsp is a worldwide Usenet news group that is used to discuss various aspects of digital signal processing.

We found 92 threads matching "invariance"

You are looking at page 1 of 3.

The most relevant threads are listed first

## DSP-impulse invariance method 0

2006-03-12 11:18:00
Now, I use the impulse invariance to design a lowpass filter. I need to find the H(s) from pole pairs. I don't know how toconvert H(s) to H(z). Can anyone help me? Thanks!! Laura ...

## help regarding impulse invariance method ! 0

nikkogta4 - 2009-04-13 09:48:00
Hi, i hav just studied the impulse invariance method & bilinear transform. In Impulse Invariance there is "many to one mapping" and hence aliasing takes place. while in Bilinear Transform there is "one to one mapping" and hence no aliasing. Actually what is the "one to one mapping" & "many to ...

## Re: Independent vs uncorrelated 0

Ben - 2006-07-04 05:40:00
The confusion is thus: In an earlier post you implied Uncorrelated ------> rotational invariance ....(A) and Spherical Symmetry --------> rotational invariance ....(B) (B) may be accepted as an axiom of spherical symmetry, while (A) has been proven in an earlier post. What i...

## Re: IIR Gaussian Transition filters 0

Greg Berchin - 2010-09-29 12:15:00
On Wed, 29 Sep 2010 08:18:48 -0700, "Pete Fraser" wrote: > Is there any software around that designs Gaussian transition > filters? ScopeIIR and Matlab both deal with most of the > Zverev standards, but neither deals with GT. What is the difference between a Gaussian filter and a Gaussian...

## Re: resume of the defintion of a linear system 0

Gordon Sande - 2004-05-15 15:47:00
On 14 May 2004 05:10:45 -0700, kriari21@yahoo.co.uk (Odisseas) wrote: > Dear all, > > there is sometime now that I am trying to solve a simple(??) problem > and I experience difficulties. > > The problem is this. I am trying to give a brief resume of the > definition > and basic propert...

## Re: DFT Symmetry with Complex Input 0

Gordon Sande - 2005-02-20 09:52:00
Rune Allnor wrote: > Jerry Avins wrote: > > > Rune Allnor wrote: > > > > ... > > > > > > > Humm... I agree with you in your general comment about signal > > > representations, but I think my first statement can be defended. > > > The complex exponentials _are_ the basis functi...

## gain response 0

caine - 2007-04-24 23:22:00
I have to design Chebyshev type I analog lowpass filter and transform it to digital filter using impinvar() and bilinear(). Then I have to plot the gain response for both methods and do comparisons. However, the gain response take in the input of g of 20log10(H)?? function X = invariance(fs) ...

## gain response 0

caine - 2007-04-24 23:28:00
I have to design Chebyshev type I analog lowpass filter and transform it to digital filter using impinvar() and bilinear(). Then I have to plot the gain response for both methods and do comparisons. However, the gain response take in the input of g of 20log10(H)?? function X = invariance(fs) ...

## Question about IIR filter design using Impulse Invariance method 0

Bobby - 2004-11-13 13:36:00
I am designing low pass IIR filter using Impulse Invariance method. I've got transfer function H(z) which depends on impulse sample period T. I was asked to choose an appropriate impulse sample period T for H(z) such that the input signal x(t) = 5 cos(2pi(8000)t ? pi/3) ? 4 cos(2pi(40000)t +...

## Re: convolution 0

julius - 2007-08-12 12:14:00
On Aug 12, 1:16 am, gyansor...@gmail.com wrote: > On Aug 12, 5:05 pm, lee wrote: > > > hi guys.....i am beginner in dsp..... > > Can somebody tell me the physical meaning of convolution.....wht does > > it do actually?? > > It's the process that a linear system has to perform in ...

## Re: LP Filter - Minimize Ringing 0

Greg Berchin - 2008-10-22 14:33:00
On Wed, 22 Oct 2008 11:00:44 -0700 (PDT), Chris Maryan wrote: > Bessel! Aha! Forgot about those. Ok, now the question is, how do I go > about developing the linear phase, FIR equivalent of a bessel filter? Bessel filters approximate Gaussian pulses in both domains. So you could start th...

## Re: How to show y(t)=x(-t+1) is not time-invariant? 0

Jazz - 2005-07-23 07:51:00
kiki wrote: > Can anybody give the proof step-by-step and not handwaving...? > > As you can see, I still don't quite understand. Hey Kiki, there is only one way to check for time invariance and that's using its definition. It says that a system is time invariant iff shifting the inpu...

## Re: IIR approximation with FIR 0

Greg Berchin - 2011-10-05 08:51:00
On Tue, 4 Oct 2011 21:41:51 -0700 (PDT), OutputLogic wrote: > At this point I'm thinking of taking an impulse response of the IIR > and simply "truncating" its tail. Is this going to work ? There is > some margin of error that can be tolerated. Yes, it is going to work, provided that you ...

## Re: Systems Knowledge Question 0

Phil Hobbs - 2011-08-08 23:25:00
On 08/07/2011 03:15 PM, Tim wrote: > Please answer without looking at Wikipedia or otherwise finding the > answer. Please answer, even if the answer is "no". I'm trying to get a > measure of the extent of a bit of knowledge, here: > > How many of you know, off the top of your head, that ...

## Re: Nomenclature question - what does LTI imply 0

Tim Wescott - 2011-08-02 01:42:00
On Mon, 01 Aug 2011 21:39:17 -0500, Richard Owlett wrote: > It's been ~40 years since I took a "Signals and Systems" course and > never used most of it in the "real world" ;/ > > Recently I've been thinking -- an admittedly dangerous hobby. > > IIRC all the LTI networks I encountered...

## rotational invariance 0

dymin3 - 2010-04-24 21:46:00
I am having difficulties to solve the following question. Would you please help me? suppose that X and Y are independent and each rotationally invariant on R^k a) Let X = X1 with Xi on R^k1 where i =1,2 and prove X2 - Each Xi is rotationally invariant in its own right - If Vi is ...

## Re: obtaining discrete-time model from impulse response or transfer function 0

robert bristow-johnson - 2011-08-28 20:17:00
On 8/28/11 4:53 PM, Vladimir Vassilevsky wrote: > > > robert bristow-johnson wrote: > > > another method of discretizing your continuous-time model is the > > "Impulse Invariant" transformation. in that, you define the > > discrete-time impulse response to be a sampled copy of the > >...

## Re: LTI system and Non LTI system 0

Ken Davis - 2005-02-15 15:53:00
"Abdul" wrote in message news:cuslvf\$52c\$1@rzsun03.rrz.uni-hamburg.de... > Hi, > > Let > > X(n)-----> Input Discreate Time Sequnece. > H(n)-----> Impulse response of the system. > Y(n)-----> Output Discreate time Sequnece. > > X(Z), Y(Z) are the z trasfroms of Input &...

## Re: Analog to digital filter conversion 0

Noway2 - 2005-10-17 13:14:00
I found the examples in Richard Lyons, Understanding Digital Signal Processing book to be very helpful in understanding the application of implementing the Bilinear Transform, as well as the Impulse Invariance Method, when I began studying DSP. In the book, he takes you through the process ste...

## Is complex-conjugation an LTI operation? +1

Oli Charlesworth - 2009-11-24 04:57:00
Good morning all, This conundrum may be due to it being too early in the day for me to think clearly, so please tell me where I've gone wrong! It would appear to me that complex conjugation would satisfy the properties of linearity and time-invariance, and therefore could be categorised as ...

## Re: Bode's Amplitude/Phase relation for discrete time systems 0

Mikolaj - 2010-05-25 15:16:00
On 22-05-2010 at 23:22:20 HardySpicer wrote: > Of course we know that but there are at least two other methods we can > use, forward and backward difference and one of these is also > guaranteed stable. These are in fact mathematical methods for "aproximation" of a group of differen...

## Re: frequency scale in IIR design 0

Rune Allnor - 2008-09-22 08:40:00
On 22 Sep, 11:46, skyworld wrote: > On 9=D4=C222=C8=D5, =CF=C2=CE=E75=CA=B139=B7=D6, Rune Allnor wrote: > I > know in FIR design I need to do normalized by f' =3D f/fs, but in this > IIR example, it seems different. That's because the impulse-invariance design of IIR filters relates...

## Re: Conversion from S-domain to Z-domain? 0

Jerry Avins - 2007-02-09 18:08:00
yijun_lily@yahoo.com wrote: > Hello, > > Is the bilinear the only way to convert from S-domain to Z-domain? > > I am thinking of the relationship among poles and zeros in these > differenct domains. Can we just map the pole and zeros in S-domain > into the poles and zeros in Z-domain...

## impulse response of a nonlinear filter 0

fisico32 - 2010-06-25 12:26:00
Hello forum, if a time-invariant (zero memory) nonlinear filter is fed with a delta impulse, it will output a certain output. That output will be the same no matter when the impulse is applied due to time invariance.... Superposition (convolution) is not valid for nonlinear system. Is th...

## question about interchanging limit and operator in system theory 0

kiki - 2005-08-17 19:09:00
Hi all, x'(t)=limit (x(t)-x(t-h))/h, h -> 0 where " ' " denotes the deriviative. Let's use "L" denotes the operator of LTI system Given L(x(t))=y(t), I want to show that L(x'(t)) = y'(t) I have to interchange the order of the limit and the system operator L, as follows: L(x'(t))...

## Re: de-emphasis filter 0

Clay - 2007-05-02 14:10:00
On May 2, 1:41 pm, "drew" wrote: > I'm trying to design a digital IIR de-emphasis filter with sampling > frequency 48 kHz and time constants T1=50us and T2=15us. I've used Matlab > to perform a bilinear transform of this continuous time specification, but > it seems that the frequency war...

## Re: inverse laplace transform 0

Andreas Schwarz - 2005-12-21 15:04:00
Bhaskar Thiagarajan wrote: > I'm working on trying to model a non-linear system (described by a second > order differential eqn) into a discrete IIR filter. I guess I'm trying to > follow the impulse invariance IIR filter design method. > > In the laplace domain, the transfer function loo...

## Re: Blinded by math. Was "How does an inverter affect phase?" 0

Andor - 2006-06-22 04:43:00
Jerry Avins wrote: .=2E. > Phase is a continuous function. To define a special phase with only two > discrete values as an "explanation" is mere sophistry. Calling a tail a > leg doesn't make it one. Jerry, this whole discussion is pointless, because you never defined what you mean by a "...

## Re: energy conservation in linear-nonlinear systems 0

Jerry Avins - 2010-07-30 20:15:00
On 7/30/2010 2:32 PM, fisico32 wrote: > Hello Forum, > > say we have a linear system that preserves the total energy of the input > signal x(t) in the output signal y(t). You probaly also have time invariance in mind. Certainly, superposition holds then. > That means that the spec...

## Re: DFT and resonance -- question 0

robert bristow-johnson - 2006-04-10 23:10:00
Michael wrote: > > If anybody knows of an algorithm that 'removes' overtones from a > spectrogram, or alternatively identifies the probability of a given > frequency being a fundamental vs overtone given the intervals between > very-present frequencies above it, figuring out the integer ...

## Re: how to prove that y=x((cos(t))^2 is not Time Invariant? 0

Bevan Weiss - 2005-10-17 16:25:00
novellover wrote: > Ooops, it should be y(t)=x((cos(t))^2), > > by the way, I created this problem myself... > > So please never ask if it is homework problem. > > NEVER!!! Otherwise it would be considered as offending. > > My questions are all original. > > And also pleas...

## Re: LTI 0

Noway2 - 2006-04-04 13:37:00
shoma wrote: > Let a0, a1, . . . , aM be any finite sequence of real numbers. > > Define a system L by L(X) := X * (a0, a1, . . . , aM), where X is any > discrete signal. > > Show that L is a linear time invariant system and that it's unit response > function is h where, > > ...

## Linear System Properties? 0

Till Crueger - 2004-03-26 10:20:00
Hi, I have some simple questions about the properties of linear systems. In a linear System we have to assume the properties of homogeneity, additivity and shift invariance. In a DSP book I read that from these properties you can conclude that a sine wave as input will always produce a sine wav...

## Re: Linear Time Variant systems 0

Rune Allnor - 2003-07-26 11:55:00
Vladimir Vassilevsky wrote in message news: ... > Rune Allnor wrote: > > > > [Skip] > > > Is the time variant system itself nonlinear, or is it just that no linear > > method of dealing with such systems has been found? > > > > Any thoughts? > > > The system w...

## Re: time-varying dynamic system 0

Maarten van Reeuwijk - 2005-12-21 12:26:00
robert.w.adams@verizon.net wrote: > ... My question was about whether or not it "converges" in the sense that > if the frequency becomes infinitely low, it approaches a single value > that is only dependant on when the impulse was applied, (and the amplitude > of course). I think the answ...

## Re: why is an image non-stationary? 0

Gordon Sande - 2004-11-24 08:46:00
kiki wrote: > Hi all, > > I am not sure I completely understood... > > but I've heard people say that an image is non-stationary, blah blah blah, > > what does that mean? > > and what does that imply? > > I vaguely heard that people say since an image is not-stationary...

## Re: A Text book on DSP! 0

Randy Yates - 2006-06-28 23:08:00
Raja wrote: > [...] > 2) Here is this book, "Introduction to Applied Mathematics" by Gilbert > Strang. I wanted to know that if someone takes it is up as a first text > for understanding DSP (things like FFT and Z transform) then how would > it be. Can someone kindly give a through review ...

## Re: why we want to do folding while performing convolution -6

Rune Allnor - 2006-07-21 07:49:00
steve wrote: > intuitively why do you need to flip it? I don't know The folding/flipping/convolving pops straight out as a result of the intuitive arguments behind and derivation of the convolution sum formula. The flipping as such may not be "intuitive", but once you have derived the conv...

## Periodicity , shift invariance and stationarity 0

santosh nath - 2004-11-25 02:46:00
Continuing with Tim Wescott's article I would like to ask following question Periodic signals are defined as signal which repeats after certain period i.e mathematically, f(t)=f(t+p), where p is time period (say, time domain signal). Can this signal be called as "shift invariant"? Als...

## Re: Acoustic Beamformer 0

John Herman - 2006-10-01 11:24:00
Rune may be underestimating the difficulty. Frequency invariant over several octaves and steerable in any direction makes a tough design. If you can mechanically steer the sensor to the desired direction would make things easier because you cah use a disk. Log tapering the sensors in ...
| 1 | | 3 |