Questions tagged [filters]

In signal processing, a filter is a device or process that transforms a signal by selectively choosing specific frequencies and leaving others with appropriate gain or as it is.

2,927 questions
Filter by
Sorted by
Tagged with
27 views

How do I generate invertible causal filters with stable deconvolution?

I'm writing a machine learning algorithm that needs to search in the space of all possible causal and invertible convolutions/filters of size $k$ represented with floating point precision for one that ...
• 45
1 vote
55 views

Why Does This Sliding Window Goertzel Filter Trick Work?

I'm reading an analog signal at a constant interval on an embedded device, and I want to extract a specific frequency component. Since the signal is continuously being read I want to constantly scan ...
• 11
95 views

Oversampling and decimation leads to slightly different result in frequency domain

I am trying to explore the effect of oversampling and decimation with the following Matlab code ...
• 113
97 views

RLS adaptive filter intuitive explanation of the so-called desired signal

This wikipedia page https://en.wikipedia.org/wiki/Recursive_least_squares_filter (and in fact other sources) do not explain the apparent paradox of the cost function that computes the MSE of the ...
40 views

Is there a computable operation that minimizes entropy?

I have recently experimentally learned that decorrelation does not necessarily imply good compression, but good compressions have the effect of data decorrelation. Since I cannot use autocorrelation ...
• 45
68 views

Choice of filter for accelerometer data

I had downloaded the android app Phyphox and collected acceleration data. It provides the acceleration at time t, in a CSV file. I was tasked with finding the position of the object. I would like it ...
164 views

Optimized Filters for Delta-Sigma Converters with Finite Time Limit

Quick read of my question The optimum estimator of the mean for N samples of a sampled DC level in the presence of white noise is a block average (an average with all samples given equal weight). What ...
• 52.4k
1 vote
85 views

Debugging a Haar wavelet transform in the Fourier domain

I'm trying to get a minimum-viable prototype going for a project on sensor fault detection using a scale-zero Haar wavelet (frequency-domain locality is not important). After some Googling, I managed ...
1 vote
87 views

Removing DC bias

I have a signal that I have recorded from a AirSpyHF and want to remove a unwanted narrow signal with a notch filter (see figure). The spike in the image below appears to be a center spike, however it ...
• 131
1 vote
81 views

What is the best way to emulate a tube EQ in DSP?

What is the best way to do it? Quite a noob question but could you design a linear filter then add a mask with the non-linearities of the tube (harmonic distortion, saturation, noise)? I'm sure there ...
• 153
95 views

Butterworth filter vs Elliptic filter - artefacts and huge transient

I'm working on a project involving digital filters and DFT. I want to use sampled ECG data to determine the heart rate using power spectral density. While filtering the ECG samples (samples are from ...
• 103
1 vote
94 views

Baseband downconversion without imaging

I am a high school intern at a company employing heavy DSP and trying to learn the basics from the ground up. One feature of a test application I'm creating is the ability to zoom an FFT graph and ...
• 113
45 views

Digital filter response at frequencies higher than the Nyquist frequency

In one system there is a maximum sampling limit of 500 Hz. And in the analog signal, there are waves with a frequency in the range up to 1600 Hz. With 500 Hz sampling, is it possible to remove ...
1 vote
31 views

How to do RRC filtering in multiple stages?

The goal of the approach is to speed up RRC filtering with (very) large oversampling ratio. To this end I calculate the prime factors of the oversampling ratio and RRC filter the signal with each ...
24 views

Interpolation Control for doing Timing Recovery in FPGAs

I intend to make a timing recovery circuit on an FPGA and for that I have to make synthesizable models of Xilinx Blocks for Interpolation Control (Module-1 Counter based) in Simulink. I have made ...
1 vote
82 views

Farrow filter - Effect of Delta Delay

Looking at the Farrow structure we see that the closer the specific FIR block to the output, the less effect the Delta has on it. When the output of H4 isn't effected at all by the value of the Delta ...
• 157
96 views

IFFT return complex values in Matlab

I've been experimenting with the frequency sampling method for designing FIR filters. I created a low-pass filter that has a linear transition band. However, when I performed an IFFT on the frequency ...
• 103
46 views

How to handle non-causality when decomposing a 4th order IIR filter into a parallel bank of second order filters?

What I am trying to do I am trying to code a Gaussian smoothing filter using the 4th order IIR filter described in Van Vliet's paper "Recursive Gaussian derivative filters". My code works ...
• 121
34 views

Software based energy meter

I have been implementing a software energy meter. In other words my software has to integrate immediate electrical power over time. The immediate electrical power is calculated based on following ...
• 397
28 views

Derive the filter mask that corresponds to the double filtering process

There are two mask filters, ...
• 21
52 views

16-QAM with RRC filter shows a point in the middle (bad EVM)

I build a PCB with the DAC3174 from TI and I'm using it initially to test it as a channel, like shown in the diagram from the datasheet: The analog signal is mixed with the PLL carrier frequency (at ...
49 views

What's the advantage of the multirate filter banks?

Slower clocks mean lower power consumption, any other benefits? Could the multirate filter be more sharper than the single-rate filter? Previously, someone asked the similar question, but the answer ...
23 views

BER curve versus SNR for using matched filter receiver

I want to simulate matched filter receiver with rectangular pulse shape in an AWGN channel. My goal is to plot the BER curve versus SNR for BPSK modulation. I have written the code and my curve is as ...
1 vote
65 views

Why is it said to be alias free in such a multirate system?

Page 246 in multirate systems and filter banks by P. P. Vaidyanathanm. The sampling in the first stage should have brought the aliases already, why does the author claim that it is an aliaa-free ...
42 views

How can I calculate how much of my signal at the beginning and end will be affected by the filtering process?

I'm using a Butterworth bandpass filter to process my signal (low-pass + high-pass, I am also applying a notch filter). I would like to calculate how much of my signal at the edges will be affected by ...
104 views

Smoothing Filter on Signal

With python scipy I am processing (in real time) chunks of 250,000 each a CW pulsed beep radio signal in python from a RTLSDR. The signal after some basic processing and decimation is 9995 samples ...
• 131
43 views

38 views

Fiber Photometry (Fluorescence) Signal Preprocessing through Source Separation and Baseline Correction

I am working on preprocessing fiber photometry data. The data collection involves inserting fibers into an animal, where the reflection of specific wavelengths of light is captured. We collect two ...
1 vote
49 views

Initial conditions for 2 IIR causal filters applied to the same time-series consecutively

I have a buffer of shape (n_samples, n_channels) in which new samples are coming in at regular intervals and old samples are discarded. In this example, the buffer array is called ...
• 213
1 vote
62 views

Wiener Filter for Noise Reduction in GPS Sensor Measurement

I am getting position and velocity measurements out of a GPS sensor and I want to filter these data, so I can have a better, less noisy, estimation of the true measurements. I thought of doing this ...
47 views

Formants extraction from LPC

I would like to do formants extraction using LPC. I made the necessary pre-emphasis before feeding the speech samples to the LPC function. ...
1 vote
27 views

Removing noise from data series of road surface data

I have a data series containing underlying noise, the plot of which is : The issue is to remove the noise leaving the pattern which is raised above the lower level. The lower level is road surface ...