# Questions tagged [digital-filters]

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### RRC filter has massive impulse response

I am trying to pass a BPSK signal through a root-raised cosine filter in Octave. To do this, I convolve the signal with the impulse response of an RRC filter, defined as follows (source): The BPSK ...
1 vote
30 views

### Power of noise signal through a matched filter (Digital Receiver)

I am studying matched filters and the sense of signal to noise ratio. In a question I was given, stated that: Show that a matched filter of a signal $s(t)$ maximizes the SNR of the output on a ...
185 views

### Is it ok to use MATLAB ''freqs" command for Digital filters?

According to my understanding, IIR filters are somewhat analog as they are based upon analog prototypes such as butterworth,chbeyshev etc. Can we usefreqscommand to ...
52 views

### Autocorrelation and the dot product of complex signals

I have a question for the signal processing community. When trying to calculate the autocorrelation of an array containing complex data, could the result be purely imaginary, and is there any ...
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### How to determine the transfer function of the second order FIR filter?

I need to find the transfer function of the second order FIR filter. I searched a lot in the standard textbooks, but I could not get the mathematical expressions and derivations. I want that the zeros ...
1 vote
76 views

### How can I reverse engineer the parameters of this butterworth filter?

I am trying to develop an application which will need a bandpass filter. The sampling rate is 30Hz, and the frequency range I'd like the filter to preserve is: 0.5Hz-4Hz. I've used mkfilter to ...
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### Range of difference equation coefficients in practical FIR/IIR filters

In the design of practical FIR and IIR filters using difference equations, what is the range of coefficients that is employed for practical filters. How many orders might be used? What might the range ...
57 views

### question about time delay of practical filter design with sampling frequency

most system have 48khz and if i have 40tap low pass fir filter that cutoff freuqency is 300hz, filter delay is 1/48000*20 = 0.0004s but the frequency resolution is very sparse and i think if the ...
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1 vote
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### Minimal group delay filter to remove harmonics but preserve fundamental

I have a signal that contains energy at a fundamental frequency (60 Hz) plus significant energy at harmonics (2nd, 3rd etc up to 15th). The signal is sampled by an ADC at 1920 Hz. I want to construct ...
421 views

### High Dynamic Range FIR Filters

Related to this question on using the Windowing method for FIR filter design versus the optimized algorithms such as least squares (firls in MATLAB, Octave and ...
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1 vote
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### GNU Radio Low Pass Filter doesn't work as expected with different transition widths

I'm new to GNU Radio and signal processing. I don't know if the following is a simple question, but I have been scratching my head about it. I created a simple flow graph with a random source (0-3) ...
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### Modelling and testing fixed point IIR filter with freeware tools

I understand from this other question that prior to implementing a fixed point IIR filter on a particular microcontroller target it's best to create a model using a DSP tool and compare the output to ...
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### Issue Understanding Time Delay of a Digital Filter

I am new to the world of digital filters and am educating myself with the book Introduction to Digital Filters by J.O Smith III,. The author derives the frequency response of a very simplistic filter: ...
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### Implementing a Butterworth Filter Manually in C/C++ via Second Order Sections

Short background: I want to implement a lowpass butterworth filter in C/C++. The end goal is to use this in a low-latency Python program, for which of course ...
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### Pressure signal

I have got an raw file which has pressure and time and temperature format and after coding I have got the plots but my main task is to analyse the data and understanding the influence of Bessel and ...
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### What is the warm-up period of a Butterworth filter?

I am not sure if I use the correct term which may be the reason why I was not able to find the answer, but what I mean by the warm-up period is the number of samples required for the filter to produce ...
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### Find the output signal in a Low Pass Filter for a given cutoff frequency range

I have a scenario where 𝑥(𝑡)=2⋅sin150𝜋t +sin250𝜋t and g(t)=𝑥(𝑡)sin250𝜋 . The signal g(t) is passed as input through an ideal lowpass filter with cutoff frequency(fc)= 300𝜋 and passband gain= 3....
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### What is the duration of the transient response in FIR filters

I have read that for FIR filters, the duration of the transient response is equal to the order of the filter. But, for linear phase FIR filters constructed with the windowing method, the transient is ...
1 vote
116 views

### implement bandpass filter on complex valued signal? (C++)

I want to filter out complex valued samples - Bandpass filter. I have 100 complex samples and I wish to filter out a range of frequencies from it, as you can see in the result of the FFT, there are 3 ...
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### Composing digital filters

I'm interested in composing filters for realtime audio processing on an microcontroller (MCU). Ideal frequency response is unity as a default, with deviations up and down at specific freq-domain ...
120 views

### Why do FIR linear interpolators have linear phase?

I wonder why linear interpolation is a linear-phase FIR filter. In fact, I am reading Dr. Rice's great book "Digital Communications; A Discrete-Time Approach," and he mentioned on page 466 ...
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1 vote
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### Expression of output for discrete time causal filters

I have a question about the expression of the output of a discrete time filter described by its impulse response $h(k)$. Looking at the defintion of a discrete filter with input $u(k)$ and output \$y(k)...
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### Pulse-shaping FIR filter

I understand that pulse-shaping is performed to limit the bandwidth of the transmitted signal, but I would like to know how pulse-shaping can be implemented using an FIR filter.