Questions tagged [filter-design]

Fiter design is the process of designing a filter.

Filter by
Sorted by
Tagged with
5
votes
1answer
5k views

Relative performance of RLS and LMS filters

It's known that the RLS filter converges faster than the LMS filter in general, but that if you're tracking time varying parameters the LMS algorithm can perform better. My question is under what ...
4
votes
2answers
562 views

Choice of cost function in adaptive noise cancellation

Why is the least squares cost function used in adaptive noise cancellation with the recursive least squares (RLS) algorithm, but the mean squared error used in signal estimation? For an ergodic ...
4
votes
2answers
2k views

Realtime filtering on a microcontroller, with dynamic cut off frequencies

Is it possible to dynamically filter a signal in realtime on a microcontroller? What I mean by dynamically is to change the cut off frequency of the filter on the fly. I have some DSP knowledge ...
2
votes
1answer
474 views

IIR filter design in digital domain using the magnitude squared

Does anyone have any good references for deriving parameters of an IIR Low pass/High Pass filter directly in the digital domain using the magnitude squared at the corner frequency? I have been able ...
5
votes
1answer
850 views

IIR filter parallelization

Is there any current ideas about IIR filter algorithm parallelization with thread count greater than filter order? Ideally, parallelization method should load GPU efficiently.
5
votes
2answers
1k views

Bessel filter second-order sections Q and Fc multiplier derivation

A practical guide for digital IIR audio filters has cookbook-style values for creating higher-order Bessel filters out of biquads, but the values listed aren't very precise: ...
5
votes
2answers
383 views

how to extract telephone audio only from an mp3

I have mp3s of radio talk shows in which the host interviews people on the phone. The host uses a microphone, and the interviewee uses either a landline phone or a cell phone. I want to save just the ...
1
vote
0answers
132 views

Chebfun versus Parks-McClellan

There is a Matlab-based package called Chebfun that (among other things) computes polynomial approximations of functions. See here: http://www2.maths.ox.ac.uk/chebfun/. I don't know anything about ...
2
votes
1answer
3k views

IIR filter design in matlab

I have to design 2 IIR bandpass filter with the following specifications: Sampling frequency 1000 Hz Pass-band 50 Hz to 200 Hz Order 6 using bilinear transform and impulse invariance with Butterworth ...
0
votes
1answer
245 views

Implementing IIR filter using FSM

How do I implement an Infinite Impulse Response (IIR) filter using Finite State Machine(FSM)? The problem is FSM has finite memory, but an IIR filter has infinite outputs. The closest match is this ...
3
votes
1answer
1k views

Online filter for EEG

My goal is to build a real-time filter for EEG data. The data are being recorded in 512Hz and I wish to filter it (in a real-time, from 0.5Hz to 30Hz in the most optimal way). Unfortunately I'm not ...
2
votes
1answer
143 views

A filter for for a realtime system?

Apologies if this is too basic. I need to implement a band-pass filter, for a realtime system. Not sure what to use. FIR? IIR? Something else ? Any tips would be highly appreciated.
7
votes
3answers
1k views

What is the ideal FIR length, given a specific pulse length?

I am trying to ascertain what the 'ideal' FIR filter length should be, given the pulse length $T_p$ of a windowed sinusoid in noise that I seek to filter. As parameters into an FIR filter that I ...
3
votes
2answers
4k views

A Simple Lowpass Filter Behaving so Strangely

I don't know much about filter design. After reading a few articles on wikipedia I am playing with filter design and I see something weird and would like some help in understanding what exactly is ...
1
vote
1answer
110 views

Vestigial Filter problem?

I have been stuck on this question for a while now. It has to do with vestigial sideband. I wasn't sure if I should be dividing $H(\omega)$ graph values by 2 because only the positive side of the ...
3
votes
2answers
454 views

Reverse Engineering Bessel LPF (sample frequency needed)

I have the following sourcecode. For all I know, it should be a Bessel LPF at 10Hz. Is there a way to get the sampling frequence out of this? ...
7
votes
1answer
2k views

Choice of Gaussian kernel parameters when lowpass filtering before image resampling?

I need to decimate a signal by a factor of q. More specifically my signal is a 3D "image": $\ I(x_i,y_j,z_k)$, which I need to downsample by a factor of two in the z direction. I want to do lowpass ...
1
vote
1answer
227 views

Applying a filter kernel defined by a continuous equation in the frequency domain

I have a filter kernel $K(\omega)$ completely defined in the frequency domain as a continuous function of angular frequency $\omega$. I know $K(\omega)$ defined as a continuous mathematical equation. ...
1
vote
1answer
4k views

Pre-emphasis / De-emphasis filter design

I've designed a simple FM communication system and found that high-frequency noise is a real problem. It appears that this is a well known issue, which has been solved through pre-emphasis of high ...
6
votes
1answer
11k views

FIR filter gain

I'm writing a C function to generate bandpass FIR filter coefficients using a simple window method (more details here FIR filters by windowing) The important code snippet is the following (f1 and f2 ...
3
votes
1answer
134 views

Characterizing real-time sampled signal

I have a signal which is sampled in real-time. At every time interval I receive a value. I need to characterize this signal as active or inactive (to take priority in the control actions). By active ...
8
votes
1answer
2k views

Oversampling and decimation: What filter to use?

I have a sensor producing (more or less) bandlimited data with a cut-off of about 45Hz, with a roll-off and AWGN. I have an ADC that samples said signal at 800Hz, with a single-pole anti-aliasing ...
2
votes
2answers
1k views

Matlab filter design,through group delay

I have the measurements of a filter’s Group delay and S-parameters. The S-parameters are of the following form, presented in a touchstone file. !Agilent Technologies,N5242A,MY49421489,A.09.33.09 !...
7
votes
1answer
143 views

Abs(poles) < 1 by what margin for a stable filter?

I checked the literature for recent algorithms used to design a digital filter that is a minimax approximation of a desired frequency response. All the articles I found work out examples where all the ...
4
votes
2answers
894 views

Downsample Equiripple FIR filter

I am designing some Downsampling filters using the remez exchange algorithm (Matlab FDAtool). I see that some times i get a spike at the first and last coefficients. does anybody knows why is that? my ...
7
votes
2answers
2k views

Phase-shift filter design

If a time-domain signal has sharp corners, its frequency spectrum will contain high-frequency components. Truncating the spectrum results in Gibbs' phenomenon. So if you're trying to design an FIR, ...
16
votes
5answers
46k views

How to write lowpass filter for sampled signal in Python?

I have some signal that sampled each 1 ns (1e-9 sec) and have, let say, 1e4 points. I need to filter high frequencies from this signal. Let say I need to filter frequencies higher than 10 MHz. I want ...
1
vote
0answers
144 views

Finding The Coefficients of the digital filter?

I want to design a digital filter for pulse shaping. Pulses are of 100us Fall time. and the sampling rate is 100MegaSamples/sec. and the Shaping time is 5us. What should my coefficients be??? And how ...
3
votes
1answer
361 views

How to remove color cast from HSV information

I have hue, saturation and value of a color (HSV color-space). The color has to be set on a device that displays them incorrectly. If I specify white it displays light magenta. However, if you specify ...
5
votes
1answer
1k views

Correlation filter output range normalization

I'm developing correlation filters based image recognition. I implemented MACE correlation filter in matlab: training code: ...
4
votes
1answer
2k views

How do you calculate the gain of a matched filter?

I know that you can calculate the gain of a low-pass filter by summing the filter coefficients. I don't know how to calculate the gain of an arbitrary matched filter. For instance, I have created a ...
5
votes
1answer
394 views

Filter design with a phase delay specification?

Given a desired filter magnitude response, plus acceptable linear phase and minimum phase FIR filter approximations, how can one design a filter with the given response and a delay specification of ...
28
votes
4answers
27k views

What is the true meaning of a minimum phase system?

What is the true meaning of a minimum phase system? Reading the Wikipedia article and Oppenheim is some help, in that, we understand that for an LTI system, minimum phase means the inverse is causal ...
16
votes
1answer
1k views

How to deal with a negative pole (unstable) in the pre-filter of a control system?

So while answering how to design a PI controller for a first order time delayed system (Question Here ) Here is the closed loop equation to a control system: $$ G_C(s) = \frac{\frac{K}{T}(1-sT)(s)...
3
votes
1answer
86 views

How do I keep a value between known bounds in an open system?

I detect points in images with an algorithm. The only parameter is a threshold T that I can modify at each image. Such images are from a continuous video, so each ...
4
votes
2answers
2k views

Designing A Filter Using SPTool In Matlab

I am currently working on learning DSP and for my course we use Matlab. I have been tasked with designing a low-pass filter using SPTool with the following specification: A Low-Pass Kaiser Window ...
4
votes
3answers
4k views

How to initialize an IIR filter in Matlab

I designed an IIR filter and want to do zero, step and projection initialization. There is mention in different reference papers but no explicit examples for Matlab. How do you do IIR initialization,...
6
votes
2answers
1k views

How to remove a tone/interference from a signal, without using classical linear filtering

I am wondering if a methodology(ies) exist for essentially 'filtering' out a tone or interference, WITHOUT resorting to classical linear filtering techniques. (band pass filter, etc for example). ...
10
votes
2answers
1k views

Understanding a Bainter Circuit (chebychev filter)

As part of a class in Signal Processing, I am building a 3rd order Chebychev band reject filter. We implement this by using three cascading Bainter circuits. Although not part of the class, I have a ...
11
votes
3answers
3k views

How to create a distortion compensation filter

I am creating a channelizer that consists of a complex mixer, CIC decimator, and a FIR compensation/decimation filter. The final FIR filter may, if it matters, be implemented as more than one filter. ...
43
votes
6answers
43k views

Simplest way of detecting where audio envelopes start and stop

Below is a signal which represents a recording of someone talking. I would like to create a series of smaller audio signals based on this. The idea being to detect when 'important' sound starts and ...
3
votes
2answers
502 views

With respect to the dirac delta function, what does $\delta [x + 2A, y - A]$

I have come across the following function and I'm trying to figure out what it really is. I have this function: $f[x, y] = \delta [x + 2A, y - A] - \delta [x - A, y + A]$. The $\delta$ is ...
1
vote
0answers
1k views

Normalizing Negative filter coefficients for Digital filter design

I am designing a High pass Digital filter. I calculated the filter coefficients using fdatool and got some negative filter values. Now, I need to convert them into values from 0 to 255. In case of ...
4
votes
2answers
6k views

Polyphase Decomposition in Matlab

I created the lowpass filter h = firls(100, [0 .2 .25 1], [ 1 1 0 0],[.001 60]); My goal is to get four filters $H_{k}(z) = H(W_{4}^{k}z) k =0,1,2,3$ From my ...
5
votes
4answers
861 views

Polyphase filter notation

Hi I am a little confused on what the notation of the following statement means. $$ H_{k}(z)= H(W_{4}^{k} z), k = 0,...,3$$ It comes from a question in which I have designed a FIR low-pass filter $H(...
16
votes
2answers
1k views

What are the differences between these two Gabor filter functions

I need to enhance the visibility of veins on dorsal hand vein images in my project. I use two different even-symmetric Gabor filters bank improve vein visibility. First bank consists of these gabor ...
8
votes
1answer
5k views

Applying FIR filter to data with different sample rates

I have a filter design, and it filters over a 1-2 kHz range. What should I do if I want to apply it to data with a different sample rate than the one for which it was designed? Let's say it consists ...
6
votes
1answer
718 views

How to estimate taps required for Parks-McClellan filters

I have some code based on Jake Janovetz's Parks-McClellan (Remez) filter generating code. How can I estimate the number of taps required to build a lowpass filter given requirements for pass band ...
12
votes
3answers
3k views

“Low-pass filter” in non-EE, software API contexts

I am an experienced software engineer and am working on smartphone sensors. I've taken fundamental EE classes in DSP and am trying to apply my knowledge. I believe that I understand convolution, ...
6
votes
1answer
1k views

Implementing a Matlab filter to cancel cross talk between two sensors

I have two sensors that have a cross talk between them. I would like to cancel the cross talk. For this I recorded two tracks, where sensor no.1 (called x1) has some input, and sensor no.2 (called x2) ...