A band-pass filter is a device that passes frequencies within a certain range and rejects (attenuates) frequencies outside that range.

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Minimum Sampling Rate of Bandpass signal

Consider a DSBSC signal s(t) = m(t).cos(2.pi.20k.t) where say m(t) is multi-tone signal with frequencies less than 5 kHz. The ...
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34 views

Apply band pass filter (BPF) before calculating the power of a signal (PSD)?

From my understanding PSD tries to give a good estimation on the power each frequency attributes to the overall signal power. If I am only interested in a frequency range $(\omega_0 \leq \omega \leq ...
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Complex band pass filter

I'm trying to find some mathematical docs about the complex (analytic signal) band pass filtering in discrete time. I've read some text already but most of them describes the problem in real time ...
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30 views

Bandwidth of M-ary modulation schemes

I am confused with regard to how bandwidth increases with increase in number of bits transmitted for given duration. 1) Usually say in PCM system, when we increase the number of bits (n) for a given ...
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20 views

Baseband vs Passband simulation in terms of noise impact

From other posts I understood that it is normally no problem to simulate a communication system in the baseband though it is carrier modulated in reality. It just speeds up the simulation. But what ...
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54 views

buidling a bandpass filter without using inbuilt functions

I got an assignment which require building a bandpass filter without using any inbuilt functions. I wanted to create a third order Butterworth bandpass filter ...
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44 views

Baseband vs Bandpass Signal

I cannot find any reliable or reasonable differences between the two even after searching for it! Please tell me the possible differences with reasons and reference links!
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80 views

From lowpass to bandpass

I have to do two frequency shifts: the first: to transform a lowpass filter into a highpass filter I've implemented it in this way: h_hpf=h_lpf.*exp(j*pi*(0:N)) the second: to transform a ...
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29 views

MATLAB appears to be applying my filter to the spectrum twice, once on each side

So it looks like MATLAB is applying the filter to the "negative" and "positive" frequencies separately and I end up with two band pass regions with a null around zero. I want the whole spectrum ...
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39 views

why bandpass filtering (butterworth) centers the signal

I run bandpass filtering via the butter() in matlab to apply butterworth bandpass filtering to find out the signals are centered at zero after the filter. Would ...
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75 views

Reconstruction of BandPass Signal from Complex Envelope

From what little I've been able to gather, the complex envelope preserves all information required for the reconstruction of the original signal and that it basically sends a low pass version of a ...
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59 views

How is the ends of a bandpass filtered signal reliable after applying the cosine taper?

A taper function decaying to zero at ends such as a cosine window is routinely applied to the signal before bandpass filtering to reduce end effects. Obviously the window alters the waveform. So, as ...
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33 views

Accurate Noisy Signal Filtering

I'm looking for some ideas to filter a noisy signal. my sampling Condition is : ...
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74 views

Signal power without FFT

I have an EEG signal thats about 1second long, sampling frequency of 256Hz, measured in microvolts, and I want to calculate the power of a specific frequency band (8-12Hz) I believe the correct way ...
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1answer
102 views

Python bandpass filter - singular matrix error

I've been trying to design a bandpass filter using scipy but I keep getting a LinAlg Singular Matrix error. I read that a singular matrix is one that is not invertable, but I'm not sure how that error ...
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1answer
215 views

How to test digital filters?

First the question(s): How should I write unit tests for a digital filter (band-pass/band-stop) in software? What should I be testing? Is there any sort of canonical test suite for filtering? ...
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182 views

ECG noise filtering using FIR Bandpass Filter

I am new to signal processing and examine ECG data corrupted with noise. The clean data has a frequency spectrum like this. And the corrupted one looks like this (sorry for the different scale) ...
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48 views

goertzel or bandpass?

I try to decode freqs of 17k & 17.8k which carry on a sinus of 15ms duration. I try to decode them with a goertzel filter. It seems fine when one of the filters show a magnitude that is around ...
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92 views

Reconstruction of bandpass filtered signal from decimated version of itself

I know how to up-sample a discrete, real signal (by an integer factor n) that is band-limited to frequencies between $f_1 = 0 \mathrm{Hz}$ and and $f_2$: Just insert $n-1$ zeros between every original ...
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1answer
154 views

Normalizing the magnitude of Goertzel Filter c#

I'm trying to detect some frequencies of 18Khz with sample rate of 44100 [samples/sec]. When I pass a buffer(~4500 samples) to the algorithm it returns a magnitude in a very strange range. Sometimes ...
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401 views

What is the right way to extract particular frequency phase information from FFT?

Signals acquisition: Two proximity sensors are positioned Orthogonal to each other. These would be measuring the vibrations of a rotating shaft. Problem: Each of these 2 signals has two dominant ...
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1answer
92 views

What is sound output delay of a band pass filter at different freqencies?

I measured that a 2-pole band pass filter, given imput audio of different frequencies, outputs an audio signal with different time delay. At 440Hz, the time delay between of the input audio and the ...
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1answer
94 views

Tradeoff between Filter Order and Sections

I have designed a bandpass IIR butterworth filter with desired response using the MATLAB FDAtool with the configuration shown in the figure below Since this is multistage implementation, when I ...
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1answer
110 views

Matlab FIlter coefficients to CMSIS api

I am trying to implement iir Band Pass filter design in STM32F429i discovery kit. I konw that it needs coefficients to be generated from matlab and feed them into cmsis api to achivi filtered data. ...
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353 views

Calculating FIR filter coefficients with the windowing method and Convolution algorithm [closed]

Please advice how to calculate FIR filter coefficients with the windowing method using the Rectangular Window function and convolution method? What utility or FIR design application can perform this ...
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491 views

How to design a narrow band pass filter without DSP toolbox

I've two signals X and Y. These are proximity sensors reading measuring vibrations of a rotating shaft. Now I want to plot orbit plots for these signals. I can plot unfiltered orbits with just X and ...
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1answer
737 views

How is the lowpass to bandpass transformation derived?

I'm using a lowpass to bandpass filter transformation: $$ s \leftarrow Q \left( \frac{s}{\omega_0} + \frac{\omega_0}{s} \right) $$ Based on the wiki article: ...
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1answer
28 views

How to determine stopband of discrete Gaussian, stdev sigma, support N

I would like to analyse a gaussian smoothing kernel with a set standard deviation and support (let's say, in MATLAB, fspecial('gaussian', [5 1], 1.3) so sigma is 1.3 and support is 5) in the DTFT ...
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Ideal BandPass Filter

Let suppose x(t)=$\sum\limits_{k=-∞}^∞ R(t-kT)$ $R(t) = \begin{cases}1 &[0,2T] \\ 0 & \text{otherwise} \end{cases}$ x(t) is the input to an ideal bandpass filter with $\text{BandWidth} = ...
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54 views

Output of a band pass filter

Signal x(t) = | cos(2πft)|, f != 0 is the input of an ideal band-pass filter with bandwidth B = 3f/2. How can i Find the ...
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1answer
126 views

Apply FIR filters to Extract Stego from WAV data

I appreciate anyone that takes a moment to help me with this problem. I've been banging my head against the keyboard for a while, searching forums and DSP tutorials and I can't figure this problem ...
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77 views

BandPass and StopBand FIR filters (Hamming) is not working

I have two groups of 3 frequencies of tone (music), First Group Tones: 39 (77.7817 Hz), 40 (82.4069 Hz) and 41 (87.3070 Hz). Second Group ...
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243 views

Why is this MATLAB butterworth filter giving me wrong results

Given a 128 Hz signal, in MATLAB I entered the following command ...
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1answer
81 views

Identify the system from input and output

I am using Excel. If I have an input and an output, and I know that a recursive band-pass filter produced the output, how can I can find the coefficients of that filter?
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277 views

A filter in IOS to eliminate a certain frequency range

I am making an application where I record sound on an IOS device using the built-in microphone. I want to process the sound in such a way that only frequencies in the 16-18 kHz range remain; the other ...
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140 views

Implementing digital filter by padding with zeros

I am making a 9th order digital bandpass filter with lower and upper corners of 200 kHz and 40 MHz respectively. I am using this filter to filter a 1D time domain signal which is 64k samples long ...
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Multiply filter kernel by sine

1)Suppose that we have low-pass filter with cf equal to 0.1. How frequency response would look like if I multiply filter kernel by sine with frequency say 0.3? How this is related to converting ...
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4answers
148 views

The reasons for filter explosion

Assume signal $x$, sampled at $f_s = 44100\; \mathrm{Hz}$. I tried to filter it using the Butterworth bandpass filter ( $30\; \mathrm{Hz} - 70\; \mathrm{Hz}$) of order $8$. However, as a result I get ...
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1answer
143 views

Segmenting a frequency series: do we need band-pass filtering?

I am trying to implement what's called the "second spectrum". Basically, you do this: Take a time series of length $N$. Divide it into $m$ segment, each of length $N'=N/m$. For each segment $m$, do ...
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1answer
251 views

Design and implementation of causal band-pass filter for biosignals - what to consider? [closed]

I currently work in a project of clinical software (C#) which deals with clinical biosignals, specifically EMG and other low-frequency signals (load-cells, goniometers, and other biomechanical ...
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1answer
360 views

filtfilt giving unexpected results

I am trying to filter EEG signals using butterworth filter and filtfilt. I have gone through a lot of documentation and these 2 commands seem sufficient for filtering. However, the results are ...
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239 views

Filtering method that minimizes ringing in time domain, implementable in Python

I am acquiring data through an oscilloscope, which I am then filtering. I am doing all of this in Python. I need a bandpass filter with stop bands from 0 to .4MHz, and 4MHz and up. My pass band needs ...
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How do I manually plot the frequency response of a bandpass Butterworth filter in MATLAB without freqz function?

I have code like below that applies a bandpass filter onto a signal. I am quite a noob at DSP and I want to understand what is going on behind the scenes before I proceed. To do this, I want to know ...
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270 views

Filtering the EEG signals

I have very limited knowledge of DSP, so I apologize if my question is trivial :) I have an EEG signal from which I need to extract different frequency bands. For example, waves in the the frequency ...
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96 views

Why is beginning of this FIR filtered signal attenuated?

I apply an FIR filter passing the band around 50/1000 and attenuating the other three frequency components 30/1000, 70/1000 and 110/1000. Both filters are generated using the Remez algorithm. The ...
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1answer
165 views

Sampling bandpass signal with spectral replications

I want to clear my thinking on how to approach problems of the type characterized below. I guess what we want to do is select a sample rate of a sufficient size such that this signal can be fully ...
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2answers
161 views

Energy in baseband and bandpass signal

Is there any difference in energy content of baseband and bandpass signals? When we see their representation in frequency domain, it looks like a bandpass signal has double the energy content compared ...
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2answers
340 views

Bandpass Filter window length: filter “in phase” with sinusoidal input

Say you have a bandpass filter and you place it on 40 discretely sampled points from a sinusoid with a period of 40. Why is the bandpass filter (green curve on the image) only "in phase" with the ...
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1answer
2k views

Bandpass butterworth filter frequencies in scipy

I'm designing a bandpass filter in scipy following the cookbook. However, if I decrecrease the filtering frequencies too much I end up with garbage at high order filters. What am I doing wrong? ...
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Separating two sound file frequencies using bandpass filter matlab

can someone please help me? I have a project to implement a superheterodyne transmitter and receiver without using matlab functions that modulate. The first part which I can't seem to get right is the ...