Questions tagged [filter-design]

Fiter design is the process of designing a filter.

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3
votes
1answer
135 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
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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
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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
152 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
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2answers
941 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
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5answers
50k 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
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0answers
145 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
468 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
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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
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1answer
3k 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
422 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 ...
32
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4answers
30k 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
87 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
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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
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3answers
4k 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
47k 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
583 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
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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
7k 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
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4answers
986 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
758 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
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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) ...
9
votes
1answer
262 views

Unit Problem in Designing a Filter for a Given Auto Correlation Function

Given a WSS process with the following Auto Correlation Function: $$ r\left ( \tau \right ) = {\sigma}^{2} {e}^{-\alpha \left | \tau \right |} $$ The Laplace Transform would be: $$ R \left ( s \...
2
votes
1answer
105 views

What are the Elements of Filters for Highly Volatility Price Series with Jumps?

What are the best filtering techniques for a highly volatility price series with jumps. What needs to be considered in designing new filters for practical finance which are adaptive and highly ...
14
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1answer
543 views

Genetic or evolutionary algorithms for filter design?

For what types of filter design problems might genetic or evolutionary algorithms be useful? What kinds of genetic or evolutionary algorithms are used for DSP problems? Edit: I expanded the question ...
10
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2answers
157 views

What is this sinc doing in my LP-turned-HP filter output?

I'm trying to HP-filter a signal by LP-filtering it and subtracting the output from the original filter. To obtain the LP-filtered signal, I backward-forward filtered using a third-order Butterworth ...
25
votes
5answers
16k views

What Is the Best First Order IIR (AR Filter) Approximation to a Moving Average Filter (FIR Filter)?

Assume the following first order IIR Filter: $$ y[n] = \alpha x[n] + (1 - \alpha) y[n - 1] $$ How can I choose the parameter $ \alpha $ s.t. the IIR approximates as good as possible the FIR which is ...
11
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3answers
2k views

Documentation about filters in general

I already posted this question on StackOverflow. I got a suggestion to go for a better answer here. To make the question more concise I'm interested in an introduction to digital filters, any ...
21
votes
1answer
6k views

What is the difference between Remez exchange and Parks-McClellan filter design?

A question recently came up regarding Parks-McClellan and some of the comments point out that the wikipedia article on Parks-McClellan states, ...the Parks-McClellan algorithm is a variation of ...
20
votes
3answers
10k views

How does cascading biquad sections for higher order filters work?

I'm trying to implement an 8th order IIR filter and every application note and textbook I've read says that it is best to implement any filter of order more than 2 as second order sections. I used <...
10
votes
3answers
6k views

FIR filter compensator when using a CIC decimation filter

When decimating a narrow-band signal with a cascaded integrator-comb (CIC) filter, which FIR filter is more suitable to compensate the CIC frecuency response?
20
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7answers
8k views

Where can I get an open source implementation of the Parks-McClellan optimal FIR filter design algorithm?

Background: Often times I am doing some sort of signal processing task that requires a unique filter. Usually at this point I go to MATLAB and generate a new unique filter using $\tt firpm()$. The ...
9
votes
2answers
1k views

How to design a continuously time-variant digital filter?

I have discrete time series containing signal with smoothly varied frequency over time (called a "sweep"). How can I design a discrete filter (low-pass or band-pass in my case) of a finite length with ...

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