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Discussion Groups > Invariance

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

We found 62 threads matching "invariance"

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The most relevant threads are listed first

DSP-impulse invariance method

11:18 12-03-06
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 ...DSP-impulse invariance method

Re: Independent vs uncorrelated

Ben - 05:40 04-07-06
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: Independent vs uncorrelated

Re: resume of the defintion of a linear system

Gordon Sande - 15:47 15-05-04
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: resume of the defintion of a linear system

Re: DFT Symmetry with Complex Input

Gordon Sande - 09:52 20-02-05
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...Re: DFT Symmetry with Complex Input

gain response

caine - 23:22 24-04-07
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

gain response

caine - 23:28 24-04-07
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

Question about IIR filter design using Impulse Invariance method

Bobby - 13:36 13-11-04
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 +...Question about IIR filter design using Impulse Invariance method

Re: convolution

julius - 12:14 12-08-07
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: convolution

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

Jazz - 07:51 23-07-05
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: How to show y(t)=x(-t+1) is not time-invariant?

Re: LTI system and Non LTI system

Ken Davis - 15:53 15-02-05
"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: LTI system and Non LTI system

Re: Analog to digital filter conversion

Noway2 - 13:14 17-10-05
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...Re: Analog to digital filter conversion

Re: frequency scale in IIR design

Rune Allnor - 08:40 22-09-08
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: frequency scale in IIR design

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

Jerry Avins - 18:08 09-02-07
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...Re: Conversion from S-domain to Z-domain?

question about interchanging limit and operator in system theory

kiki - 19:09 17-08-05
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))...question about interchanging limit and operator in system theory

Re: de-emphasis filter

Clay - 14:10 02-05-07
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: de-emphasis filter

Re: inverse laplace transform

Andreas Schwarz - 15:04 21-12-05
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: inverse laplace transform

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

Andor - 04:43 22-06-06
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: Blinded by math. Was

Re: DFT and resonance -- question

robert bristow-johnson - 23:10 10-04-06
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: DFT and resonance -- question

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

Bevan Weiss - 16:25 17-10-05
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: how to prove that y=x((cos(t))^2 is not Time Invariant?

Re: LTI

Noway2 - 13:37 04-04-06
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, > > ...Re: LTI

Linear System Properties?

Till Crueger - 10:20 26-03-04
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...Linear System Properties?

Re: Linear Time Variant systems

Rune Allnor - 11:55 26-07-03
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: Linear Time Variant systems

Re: time-varying dynamic system

Maarten van Reeuwijk - 12:26 21-12-05
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: time-varying dynamic system

Re: why is an image non-stationary?

Gordon Sande - 08:46 24-11-04
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: why is an image non-stationary?

Re: A Text book on DSP!

Randy Yates - 23:08 28-06-06
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: A Text book on DSP!

Re: why we want to do folding while performing convolution

Rune Allnor - 07:49 21-07-06
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...Re: why we want to do folding while performing convolution

Periodicity , shift invariance and stationarity

santosh nath - 02:46 25-11-04
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...Periodicity , shift invariance and stationarity

Re: Acoustic Beamformer

John Herman - 11:24 01-10-06
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 ...Re: Acoustic Beamformer

Basic understanding problem of continuous-time to discrete-time conversion

Georg P. - 06:39 05-12-07
Hello, Assuming I have a time-continuous first-order lowpass filter given by the transfer function 1 Wc Hc(jW) = --------- = ------- 1 + jW/Wc Wc + jW where W is the (continuous-time) frequency in rad/s and Wc is the (continuous-time) 3dB-cutoff freq...Basic understanding problem of continuous-time to discrete-time conversion

Re: Basic systems question: Is this system time-invariant?

fred - 06:46 18-07-05
Bernhard Holzmayer wrote: > David Kirkland wrote: > > > kiki wrote: > > > y(t)=x(2*t - 2) - x(-3*t + 5 ) > > > > > > where x(t) is the input, y(t) is the output of the system. > > > > > > Is this system time-invariant? > > > > > > Thanks a lot! > > > > > > ...Re: Basic systems question: Is this system time-invariant?

Re: MLE : Random Vs Deterministic

=?ISO-8859-1?Q?Mads_Gr=E6sb=F8ll_Christensen?= - 07:21 31-01-08
Hello. > Start with your own explanation of the deterministic model above, > and note in particular the word "known." > > If you have a situation where you *know* what type of signals > you will get, then deterministic methods might work. However, > that's a powerful constraint. Popul...Re: MLE : Random Vs Deterministic

Re: How to convert continuous filter to a digital filter

Andor - 17:57 02-07-08
On 2 Jul., 15:56, "Qingeng.Deng" wrote: > hello, everybody: > =A0 =A0 =A0 I have one problem in do my master thesis, and need your help.= > The question is as follows: > =A0 I have got the impulse response functions, the formulation of which > is h(t) =3D u(t)exp(-(ln(t/tao)/sigma)^2)...Re: How to convert continuous filter to a digital filter

Re: Exam revision

Jerry Avins - 15:39 01-06-06
Noway2 wrote: > Jerry Avins wrote: > > > Noway2 wrote: > > > > ... > > > > > > > It sounds like you are being asked to describe the pros and cons of > > > both FIR filters implemented using the DFT and IIR filters. > > > > ... > > > > There are few FIRs that can be implement...Re: Exam revision

Re: Is a voltage controlled oscillator system time invariant?

faust_o - 15:21 20-11-06
Dear Rune, I'm happy that we agree on a philosophical level. However there are some points I want to clear up. In my initial questions I defined: y(t)=T_VCO[x(t)] which is a rather crude model of a Voltage Controlled Oscillator. The importance of such a model is that we can use logic to state s...Re: Is a voltage controlled oscillator system time invariant?

Re: Uniqueness of Sinusoidal waves

glen herrmannsfeldt - 17:00 19-04-05
Tim Wescott wrote: > glen herrmannsfeldt wrote: > > Sandeep Chikkerur wrote: > > > We know about the uniqueness abt sinusoidal waves when applied to a > > > linear system... (snip) > > For a linear system, including a system that includes integrals and > > derivatives sinusoid i...Re: Uniqueness of Sinusoidal waves

Re: Allpass Filter Matlab Functions

Jon Harris - 14:09 04-11-04
"Jerry Avins" wrote in message news:2uuv3cF2fi5tlU1@uni-berlin.de... > Juha wrote: > ... > > > See > > > > P. Regalia and S. Mitra, "Tunable digital frequency response > > equalization filters," IEEE Trans. Acoust., Speech, Signal Processing, > > Vol. 35, No. 1, pp. 118-12...Re: Allpass Filter Matlab Functions

Re: How can I calculate filter's coefficients by the impuls characteristic?

07:25 15-12-04
vsp76@mail.ru (Sergey) writes: > Hi everybody! > > Excuse me for easy question - I'm novice in DSP. I know how look my > signal without noises and I wanna use matched filter in my work to > dampf the noise. > > I heard what the Matched filter is the best choise for such task and I ...Re: How can I calculate filter's coefficients by the impuls characteristic?

Re: Be it resolved ...

Matt Timmermans - 22:24 17-03-04
"Jerry Avins" wrote in message news:4058698A.4010303@ieee.org... > ... that given the present bandwidth limits on a US TV channel, 441 line > images would yield higher resolution than the standard 512 lines. > [...] Your math is fine, but it doesn't argue for the superiority of either...Re: Be it resolved ...

Re: For math challenged - what is the Walsh-Hadamard transform?

Rafael Deliano - 07:22 15-09-07
> Are there physical systems that are naturally described by > Walsh-Hadamard transforms ... ? Unlikely. Rader put it nicely in his bookreview ( IEEE ASP August 1984 ) on the book by Elliott, Rao " Fast Transforms ..." Academic Press 1982: "With the next chapter begins the description of...Re: For math challenged - what is the Walsh-Hadamard transform?

Re: overlap-scrap-tail filtering -- was Re: Convolution versus LPFiltering

Andrew Reilly - 18:59 25-02-04
On Wed, 25 Feb 2004 17:41:03 -0500, Jerry Avins wrote: > But then it isn't a start-up transient. The ordinary operation of a > usual FIR has output less than perfect until as many samples have been > accepted as the filter has taps. It is possible to suppress the output > until that number o...Re: overlap-scrap-tail filtering -- was Re: Convolution versus LPFiltering
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