### Bernhard Holzmayer (@bholzmayer)

RF engineer SW and HW development in measurement and control electronics currently busy in VHDL signal acquisition and conditioning

## Re: Proving Time Invariance of a system

Using Matlab, you cannot prove anything in the mathematic or physical realm.Since Matlab is nothing but a tool. Like a desktop calculator, which can help you for...

## Re: Audio Signal Filter

Hi Roger, As Tomasz proposed, I'd use a Sharc module.I tried this way some years ago: just picked one of the available evaluation boards with appropriate ADC/DAC...

## Re: Help with polynomial zeros

If you like ScopeFIR, you might want to contact the developer.Few years ago he was very communicative - so why not ask him for a specialized version with higher...

## Re: Help with polynomial zeros

Scilab provides an open source flow. With respect to roots() calculation it has proved to be able to cope with Matlab long ago -- brought even better results with...

## Re: Help with polynomial zeros

A long time ago I had to tune a fiddly multistage radio filter (HW).I was very successful with a single stage filter, and even with two-stage filters. However with...

## Re: Help with polynomial zeros

Years ago, I ran into a problem because Matlab's root() algorithm was not able to give proper solutions just because of the internal math precision.Meanwhile I abandoned...

## Re: Is there any reliable implementation method of IIR filters with pole positions very close to the unit circle?

Some years ago, I had to implement IIR-butterworth filters (high pass and low pass) of higher order (6th-order, which is 3 consequential biquads each).I could learn...

## Re: Real Numbers

I had not such math classes - not in school and not during my studies - maybe bc. we were trained with the Electronics/Physics focus. What a pity...Only later I...

## Re: Real Numbers

Hi Cedron, Do you think this mapping by picking decimals does really make sense with respect to comparing numbers? To point out the issue: why not start with the...

## Re: Real Numbers

I remember reading a book about the life of Georg Cantor who was dealing with infinity in number theory (Aleph etc.). The author of the book stated that quite a...

## Re: Real Numbers

When reading this again, a good illustration came to my mind.If you think of the function f(x)=1/x  and another g(x)=-1/x.They have certainly the same limit for...

## Re: Real Numbers

1*2*3*7 = 42(1^0)*(2^1)*(3^2)*(7^3) = 6174(1^1)*(2^2)*(3^3)*(7^7) = 88942644

## Re: Real Numbers

I agree. There's nothing beyond. Almost.Since Douglas Adams'  The Hitchhiker's Guide to the Galaxy revealed the prime elements of its magic, its obvious.But you'll...

## Re: Real Numbers

Another issue which you have to ponder with...Real numbers is a "complete" set of numbers, and it does not contain infinity. If so, how many digits can a number...

## Re: Real Numbers

This simple proof implies that it is allowed to multiply a number with infinite decimals and that multiplication result has equal number of decimals. I'm not sure...

## Re: Real Numbers

Sure they are distinct.I'd guess it's easy to prove that 0.9999... is always less than 1.0000...Bernhard

## Re: Polyphase Filter Bank channelizer issue

Hi. I have no insight in the Xilinx modules, however 89 clock cycles between the samples is no real challenge for the FPGA solution, since you would not clock it...

## Re: Simple Voice for Demo

Hi Mark,what about a chirp (sine sweep from a certain low frequency up to one (or some) octave higher and then down again, while increasing and decreasing loudness ...

## Re: Has any one seen this window family?

Yes, AI. Sorry for my German abbreviation, but you got it :-)

## Re: Has any one seen this window family?

Hi Cedron,I appreciate your mathematical approach, and I'm sure it will reveal a whole bunch of possibilities which we either did not find or we did not understand...

## Re: How well can discrete wavelet packet transform reduce noises that are similar to the input signal in the same frequency band?

FFT is most effective, if you are able to evaluate results in the frequency domain. So is it with DWT.If you can evaluate in DWT domain, it's most effective; better...

## Re: How well can discrete wavelet packet transform reduce noises that are similar to the input signal in the same frequency band?

Three hints:1) if power line noise is high, this might indicate a wiring/connection problem, quite usual it has to do with ground issues.The closer the sensor setup...

## Re: Problem with natural logarithmic function in fixed point notation

Your mistake is by using multiplication instead of addition.If values are multiplied (divided), you have to add (subtract) their logarithms to get the same result.This...

## Re: Problem with natural logarithmic function in fixed point notation

if:  y=x*(2^24)then: ln(y)=ln(x)+ln(2^24)results in your case, where x=0.54 toy=ln(x)+ln(2^24)=-0.616.. + 16.63..=16.01

## Re: Running Sum filter

So ... your 0.6 µs is really (1/1.563MHz) ??OK. And you're doing proper upsampling to 16 MHz?For example with zero stuffing between the real values ...And you certainly...

## Re: damping filter - finite stationary error

I agree with lamabrew. Your inputs are very little, so you cannot expect much help.But given that you cannot change the resolution, the result seems perfectly filtered.If...

## Re: ADC and Complex Mixer Nyquist question

Another approach: imagine a complex signal, having two components, if we look at it in Cartesian representation: (real,imag)Now you feed your system (through ADC)...

## Re: Increasing frequency of a sinusoids after FFT of a signal

If I didn't miss the point: changing the frequency cannot leave the phase unchanged, because a higher frequency means the phase is changing faster, so you cannot...

## Re: Setting up codec on ADSP 21489

Years ago, I faced the same challenge.As djmaguire stated, digging into the details requires a lot of patience and devotedness... but it's worth the effort.The most...

## Re: Do floats provide enough resolution to store time? Or do they suffer from "Virtual Digital Jitter" because their time resolution isn't good enough?

You're right, there's a lot of problems if computers deal with time, especially if they have to derive different time-related values with different representations.But...

## Re: DSP for design verification

Hi Ivan,maybe it's not what you expect or what is in your interest, but if I'd be interested in rise/fall times or level uncertainties, I'd not try to solve such...

## Re: OFF TOPIC: A Question About PI

I agree, my claim 2 is not correct, because adding the value '0' results in the original value, at least here.So, I should have noted: "adding any value other than...

## Re: OFF TOPIC: A Question About PI

Interesting approach. There's one issue to remember: pi has been proven to be irrational.You're example with 1/3 deals with a rational number, therefore you have...

## Re: OFF TOPIC: A Question About PI

I'm sure you're not in danger to getting psychotic because of touching the area of number theory (otherwise I'd be hospitalized for long ;-).But if you're trying...

## Re: OFF TOPIC: A Question About PI

Take this challenge: what is the result of the division of  0/0 ?0? or 1? or 5?I'll help you a little:   sin(x)/x  at position 0 ?and now, (5*sin(x))/x  or...

## Re: OFF TOPIC: A Question About PI

Again, you'll find this question already solved in numbers theory.The scaling of rational numbers in fact led to the necessary existence of irrational numbers. Centuries...

## Re: OFF TOPIC: A Question About PI

sorry, that I had been not precise enough in my "speaking":Since the quest was that pi contains each number, it would have not been a proof if I would take let's...

## Re: OFF TOPIC: A Question About PI

I guess that statement is correct, although very!! irritating. I enjoyed an old book about a mathematician (Cantor) who was dealing with natural numbers, with alike...

## Re: Sign of the magnitude difference

Solve it graphically: draw a vector z1 on a paper: let's say quadrant 1, starting from (0|0).then draw a vector z2 starting from the endpoint of z1, into any other...

## Re: Somewhat Off Topic: Manipulating a PDF File.

Hi, Rick.If you are willing to use python for this purpose, which might give you quite a lot of more possibilities, it's worth checking the link below.Just copy/pasting...

## Re: What's your favorite modern DSP chip?

We're working a lot with FPGAs. You can get really cheap devices meanwhile, so price is not an issue. But if it comes to algorithms, I'd not deliberately choose...

## Re: Choosing the DFT size to match linear convolution in overlap save method?

When it comes to debugging FPGA code, bugs/monsters don't look at you!They hit back immediately :-[

## Re: Time delay

I'm very unfamiliar with all this cardioid things.But if I had to design an IIR-bandpass-filter, I'd probably start with a bode diagram and butterworth filters,...

## Re: Time delay

From the paper, I assume that you do NOT want to compensate for the delay between the microphone signals but instead want to preserve the delay (?) because it contains...

## Re: Time delay

Some hints ...1. IIR-filters are not "really" computationally cheaper than FIR-filters. They are different. Typically IIR filters cost more word-length during calculation,...

## Re: Fixed Point vs Floating Point

Imagine your digital signal stored in a serie of flip-flops (register).We'll find out a lot which may answer your questions by imagining this register.First: bit...

## Re: Is there a way to mathematically prove whether the convolution of a digital signal will lead to digital clipping?

This is not a mathematical proof, but maybe it helps to lead you to the right track...Convolution is basically nothing but multiplications and sums. Clipping is...

## Re: IIR vs FIR filtering effectiveness in voice bandwidth

Think in terms of FFT:The real spectrum of your audio is infinite, but sampling (let's say 48kS/s) will limit it to Fs/2 (-> 0..24kHz). FFT transforms the linear...

## Re: How to cancel REALLY heavy echo?

I'm not in that business, but if you would introduce a (recognizable but nearly unhearable) pattern in the voice signal, maybe you could detect that pattern in the...

## Re: Fraction saving and limit cycles in fixed-point IIR biquad implementation

High Q ends up with the same problem as a high Fs/Fcut in HPF.Therefore my guess is that your issue is not at first limit cycling (maybe later ;-), but the described...

## Re: Fraction saving and limit cycles in fixed-point IIR biquad implementation

Many years ago, I was trying to implement an IIR high-pass filter in audio-like frequency range: Fs=48kS/s, Fcut=1.5Hz (HP), 6th-order butterworth.The filter seemed...

## Re: Far Off Topic: A Simple Geometry Problem That Had Me "Going in Circles"

J join your opinion, oliviert. That's what I figured out, too.

## Re: Fundamental frequency of a Guitar string

While I agree with Tom and the others sharing their experience and questioning if you can really expect only harmonic content , just some hints from my side:often...

## Re: DSP board selection

You may want to check www.danvillesignal.com for a solution with real (Shark) dspIf it's only to get analog signals into/outof a PC: check NI/DAQpad via USB

## Re: A Mathematical Notation Suggestion

I shudder if I imagine a mathematical approach containing something like "x element of domain of Real numbers greater than zero "D. Knuth's TEX-"language" provides...

## Re: Digital Image Processing

A quick look to the s(nx) definition makes me assume that in the spectral domain you see not a single line as would be ideal for a sine response in the cont.math...

## Re: A Sinusoid with Missing Periods

I would set up a sort of PLL. Its output should give a steady sinus without missing periods.Needs to be locked to the incoming Signal.Depending on its setup it has...

## Re: Impulse behavior of FIR LP filter

Sounds interesting.I guess that all you guys are right, it's a big challenge, very close to the physical limits. So the only real chance is to find that approach...

## Re: Impulse behavior of FIR LP filter

When I tried to insert the above figure (drag and drop) it was there until I pressed "submit". After that it was not visible any more.I tried that again, it failed...

## Re: Impulse behavior of FIR LP filter

Coefficient resolution should not be a problem (filtering will be done in OpenCV on graphics card of a PC board, so tends to be 32 bits FP or better).Transmission...

## Re: Impulse behavior of FIR LP filter

Hi Fred, you got it. In the first row of your img the first sine shows a lower amplitude than the following. If only one sine pulse would be there, it's obviously...

## Re: Impulse behavior of FIR LP filter

OK. I agree, that I could have given more detailed information about the signal flow around the filter...more backgroundIt's a measurement signal coming from ADC....

## Re: Impulse behavior of FIR LP filter

Thank you for your input.Yes, the 3% value is what I would have expected, and as my graph shows depends on how good the peak of the pulse is hit.I tried with different...

## Impulse behavior of FIR LP filter

Hi all,my question may sound trivial, but maybe I need a kick into the right direction, so I appreciate your ideas...background: A pulse (best described as a singular...

## Re: IIR filters

As probbie already pointed out, IIR filters are necessary, if we want comparable results as with analogue filters. That's the reason why I use them:Previously we...

## Re: fft/ifft scaling revisited

It is mainly a matter of practical usefulness. Because, as you propose, it would be possible to normalize the factors to 1.But, if you do it as it is, this means...

## Re: Off Topic: A geometry problem

My idea to consider the right or left rim was overshoot:Only thinking about a parking position far left from B or right from A makes clear that ways are always increasing....

## Re: Off Topic: A geometry problem

If a compass and straight-edge solution is required, derivations are certainly not allowed, although I would tend to that approach too, since it's quite straight-forward.The...

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