# Questions tagged [fir]

FIR filters are filters with a finite duration impulse response.

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### What is the slope of a transfer function?

Lets say I have a Transfer function (H) plot as below. I need to find the SLOPE of the transfer function in dB/MHz. That is... i need a plot (db/MHz) vs frequency. How can i go about it ? ...
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### FIR Filter Magnitude Response

This is the shape of the bipolar amplitude function for a FIR filter with odd m: I have 2 questions : If i want to use this FIR as a low pass filter between 0 and $\frac{F_{c}}{2}$ , how can i set ...
43 views

### FIR Linear Phase Condition

This is the linear phase condition for FIR filters as expressed by my prof: I don't understand why $G(f)$ can be negative. Isn't the Fourier transform expressed in polar form ? So the magnitude is ...
43 views

### Does a raised-cosine filter have infinite support?

I recently asked a question here regarding limiting the bandwidth of a digital baseband signal and was introduced to pulse-shaping using a "raised-cosine filter". At the time, I mistakenly assumed ...
75 views

### Question about zeroes of simple 2nd order FIR filter

I have a question about the zeroes in a simple second order FIR filter. I'll list out the major beat points of calculating where the zeroes are before asking the question (I'm following "Designing ...
41 views

### Strange Response of a fir1 Filter in Matlab

i have been tinkering with some fir filters to bandpass-filter a signal. Even though the filter looks pretty descent in frequency domain, i receive a quite strange "filtered" signal in time-domain. I ...
51 views

### Meaningful output of FIR filter output

I have implemented FIR filter using tapped delay line method. I start getting output as soon as first input sample is passed to it, I am wondering from which sample I will get the proper output(...
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### How to chose a kernel function for a FIR low pass filter in audio processing?

As the answer of a previous question, I was suggested to use a FIR filter to act as a low-pass filter to reconstruct the envelope of a sound wave (edited, emphasis mine): As I said in a comment, ...
103 views

### How to use a FIR on a signal with a drifting central frequency?

I have been working on this subject for a while and I couldn't get a proper answer. I am trying to estimate the phase of the input signal : $x(t)=Ae^{j(at^2+bt+c)}+n(t)+i(t)$ Where $n(t)$ is a ...
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### how a signal for which calculate RMS can be filtered and have a fast settling time?

i designed a sinusoidal pwm amplifier (3KHz to 20KHz) that regulates its output voltage reading the RMS value of output current. The RMS is obtained squaring the signal sampled by AD converter @...
542 views

### Number of taps needed in an FIR filter to remove DC

An FIR filter is being used to remove the DC of an ECG. The sampling rate is 500Hz. How many taps would said FIR filter require (theoretically and practically) to filter out the DC. P.S. the filter ...
107 views

### FFT strong signal in middle frequency bin

I've developed a radar that I'm using to determine the distance to remote objects. It uses a custom PCB with an onboard FPGA that performs the DSP algorithms. The data from it is then plotted on a ...
115 views

### How to reliably compute the group delay of a comb filter

I applied the following FIR comb filter in real-time: y[n]=x[n]-x[n-40] Since this is an FIR, the group delay is D=(N-1)/2=20 samples. After applying the filter ...
63 views

### FIR filter format - Brutefir - Volumio

I am trying to compensate for the high frequency droop of a TDA1543 based nos DAC. One straightforward method is described here. Having played the resulting .wav, ...
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### How to Determine if FIR has a Linear_Phase Response w/o Matlab

Given the FIR transfer function: h(z) = $.36 + .384z^{-1} + .1608z^{-2} +.9712z^{-3} + .352z^{-4} + .18z^{-5} - .2z^{-6}$ How do you determine if this transfer function has a linear - phase ...
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### What exactly is stored in “output” variable in the FIR Filter code below? [duplicate]

What exactly is stored in "output" variable in the FIR Filter code below? ...
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### What are the limitations of FIR filters?

I know that for type II FIR filter it adds a zero at $z=-1$ so it cannot design a high-pass filter. My question: what type of limitations the other types have (type I, III, IV)?
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### What exactly is stored in the buffer array in the code below? Is it the values of x[n-k] or something else?

What exactly is stored in the buffer array in the FIR Filter code below? Is it the values of x[n-k] or something else? ...
225 views

### Finite impulse response FIR filters

If H(Z) is linear phase FIR filter, then what can 1/H(Z) represent? Can it be causal and stable? Can it be stable if it is not required to be causal? I think it represents non linear phase FIR ...
130 views

### Converting an FIR Filter Model to a State Space Model for Kalman Filtering

I want to try and determine the true value of a quantity $\alpha[k]$ from observations of a related quantity $\vartheta[k]$ using a Kalman filter. The observations are of the following FIR filter form:...
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### Linear phase FIR filter for impulse responses that don't appear symmetric

I would like to clarify some confusion I have about linear phase FIR filters of which do not seem to have symmetric impulse responses. Starting with a simple case, a delay, $h[n] =\delta(n-n_0)$ ...
33 views

### Wiener Filtering to perform minimum mean square estimation

As the Title suggests, I am trying to design a Weiner Filter for getting the lower bound on my LTE channel estimation algorithm. To give you a high level on the chain, First after generating the ...
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### Find the length of the impulse response of a Linear Phase Type 4 FIR filter

The length should be found such that the group delay is minimum It is given that the impulse response is real. One zero of the Transfer function is at $0.6e^{j\frac{\pi}{4}}$, and another one is at -...
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### FIR bandpass filter for complex baseband signals

I am DSP newbie and I need to apply a bandpass filter to the complex baseband signals of bandwidth 20MHz and sampling rate 61.44 MHz. Below is the octave code for the same and I have obtained ...
77 views

### What is the peak resonance of convolving with a sine FIR filter?

I'm trying to improve my understanding of FIR filters. As an experiment, I've manually created an FIR filter, whose coefficients follow exactly one period of a sine wave. I'm wondering what is the ...
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### FIR or IIR filter from poles and zeros

Is it possible to differentiate between FIR and IIR Filter just by knowing the poles and zeros of the system? If yes, how? If not, why? Thank you.
112 views

### Understanding a lowpass - comb filter implementation

I try to understand the implementation of the low-pass comb filter of the Freeverb reverberation algorithm: https://ccrma.stanford.edu/~jos/pasp/Lowpass_Feedback_Comb_Filter.html The original ...
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### Magnitude attenuation by a filter

I have a filter, with coefficients given by W=sin((2*pi*2*Ff*k/Fs)/(2*pi*2*Ff*k/Fs))*h(k), where Ff is the filter reference frequency, k runs from -N/2 to N/2 (N is the order of the filter), Fs is the ...
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### How would one design a (quasi) linear phase adaptive notch filter for a single complex tone?

While IIR notch filters are attractive, I need to retain phase linearity at the filter output. I imagine that it's possible to use a standard IIR notch filter: https://www.researchgate.net/...
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### Interpolation FIR filter Remez design criteria

I want to upsample an audio signal by a factor of 8. The technique I was going to use was to upsample by zero stuffing and then interopolate using a low pass anti-aliasing FIR filter designed using ...
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### Matlab applying an FIR filter to a signal, generated in Matlab

I want to create an FIR in Matlab and apply it to a signal (also generated in Matlab). You will find the code below. I will put my questions in order from here. 1) The filter coefficients vector "b" ...
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### MATLAB fir2 - npt and lap

This might not be the right place to ask this, but I'm hoping someone can explain two of the arguments in the MATLAB fir2 function. It is a function for designing ...
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### Get FIR Hilbert coefficients from Matlabs envelope() function

How can I get the used Hilbert filter coefficients from the Matlab function envelope()? ...
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### Length of Matlab Raised Cosine Filter Output Complex Vector

If I instantiate in Matlab a filter, a vector, and use them in the following way: ...
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### All-pass filter usage in automotive room correction

This may not be the right place to ask this question but I'll give it a shot anyways. Maybe someone here is an audiophile. I'm using a DSP called Audison Bit One HD which uses FIR filters for ...
48 views

### Attenuate the low frequencies in a speech wave

I am designing an FIR filter to attenuate the frequencies below 300Hz. I designed the filter using the ...
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### Design the coefficients of Wide-band FIR filters [closed]

It will be a great help if someone could share a content/tutorial about how to design the coefficients of Wide-band FIR Filters.
185 views

### Why Wiener filter not IIR

I would like to limit discussion to discrete time causal Wiener filter. By definition it is an FIR filter, and it also has optimality under Mean Square Error criterion within the class of linear ...
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### System identification with limited bandwidth

Given a FIR filter $h[n]$. Its action can described as: $$\mathbf{y} = \mathbf{H} \mathbf{x} \\ \mathbf{y} = \mathbf{X} \mathbf{h}$$ where $\mathbf{H}$ and $\mathbf{X}$ is a Toeplitz matrix. If $h$...
131 views

### Side Lobes in the Magnitude Response of a Low Pass FIR Filter

I have the impulse response (from the filter coefficients) of an FIR filter obtained from MATLAB's "interp" function using the command: [y, b] = interp(x, 5); % where b contains the interpolation ...
58 views

### Low-Pass FIR that keeps all values positive

Let's say, that I want to low-pass the norm (hence positive values) of an analytic signal (related to Hilbert transform). This allows me to perform experiments with the envelope of audio. For low-...
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### Designing an FIR filter in Matlab with differing number of precursor taps and postcursor taps

I'm trying to fit an FIR filter to the measured frequency response (magnitude and phase) of a device. The frequency response is essentially a low-pass filter. I'd like to vary the number of taps to ...
45 views

### Notch filters: why is $H(e^{j0}) = H(e^{j\pi})$ required?

I'm studying for the final exams and many example exercises require to design fir notch filters of length 5, given some passband and some stopband frequencies. You'...
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### How to design a bandpass FIR filter?

I want to design a bandpass filter (BPF) using a FIR filter by the window method. I have $f_{c1} = 3\, \mathrm{kHz}$, $f_{c2} = 6\, \mathrm{kHz}$ and slope is $-80\, \mathrm{dB/dec}$. How can I find ...
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### Filter design for decimation of 1.1 kHz sensor sample rate to 100 Hz processing rate

Suppose, you have a signal source which is sampled by 1100 Hz and is "somehow" band limited to either 235 or 440 Hz. In my application, that's the ST IIS3DHHC accelerometer. There is an appnote for ...
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### Plotting phase delay from first principles giving different result from phasedelay() function. Why?

I have a length 10 Finite Impulse response as shown below, and I am trying to find the phase delay of this FIR. $$h[n]=\begin{cases}0.1,& 0\le n \lt 10\\ 0,&\textrm{otherwise}\end{cases}$$ I ...
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### FIR filter not eliminating out of band noise?

I have a simple FIR filter that should eliminate all lower frequencies: ...
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### Plotting the frequency response of a FIR filter

I am trying to figure out the mechanics of plotting the frequency response of a FIR filter. For example, I have used an algorithm (Parks-McClellan), to generate a low pass FIR filter with an even ...