Linked Questions

13
votes
6answers
4k views

Is a notch filter for 50 Hz without delay possible?

I am processing an EEG signal (2 kHz sampling frequency) from hardware and the built-in filter doesn't work as intended. FIR gives a delay, and IIR is unstable. The signal of interest is from 4&...
4
votes
3answers
6k views

What does correcting IQ do?

Some software (for example SDR Sharp) has a "Correct IQ" option. This is used to get rid of the DC spike in the middle of the display. What does this setting do to the signal? What is wrong with ...
2
votes
1answer
2k views

Why do we put poles close to the zeros in notch filter?

In the book I'm studying from "Applied digital signal processing - Manolakis" it says: The problem with FIR notch filters is that the bandwidth of the notches is large. A simple way to create ...
2
votes
2answers
1k views

Moving Average for Notch filtering

I have a periodic signal(ECG) with period of ~1 seconds. It does not have features that are shorter than 0.04 seconds. For removal of 60Hz, I thought instead of implementing a notch filter, doing a ...
1
vote
3answers
2k views

Filter design - Rules of thumb regarding ratio of sampling and stop/pass frequency

The issue: I have a signal in the time domain sampled at 51.2KHz. I want to apply a highpass filter with a pass frequency of 20 Hz. The problem: Using Matlab to do that, the design of the filter ...
3
votes
2answers
2k views

FFT analysis for Vibration Signal

I am working on balancing an air-spindle. For the unbalance analysis I use an accelerometer (NI device). I have the voltage signal from the accelerometer corresponding to the vibration of spindle at a ...
3
votes
2answers
831 views

Remove square-wave pulse artifact

How can I remove a biphasic, square-wave-like artifacts from the signal, so I'll keep as much as possible information "under" the artifact? Below is the signal with artifacts: The artifacts are those ...
0
votes
1answer
619 views

What kind of filter I should use to remove the oscillations in this autocorrelation function?

I have an autocorrelation function which is shown as following, I do believe these trailing oscillating wigs are spurious and should be removed by some kind of filter. But I am not familiar with any ...
1
vote
1answer
596 views

how to create a harmonic mask from fundamental frequency?

Using an algorithm that gives the fundamental frequency across time, example https://www.mathworks.com/help/audio/ref/pitch.html (or some other one?) how would I then use that, to create a harmonic ...
2
votes
1answer
113 views

Why a pair of complex-conjugate zeros provide a nulling filter? (FIR filter case)

FIR filter having a pair of complex-conjugate zeros that lie on the unit circle, with zeros of the form: $$ z_1 = e^{j\omega_i}\qquad\text{and}\qquad z_2 = e^{-j\omega_i} $$ And transfer function: $$ ...
1
vote
2answers
107 views

Efficient double upsampling of a pure real tone

Has anyone seen this trick before? Let's say I'm working with a real pure tone signal that's dangerously close to Nyquist. So, I want to upsample it by a factor of two to move it near the four ...
0
votes
0answers
413 views

How to choose notch frequencies for filtering line noise?

I'm using the function to filter out line noise at 60 Hz (and 120, 180 Hz) caused by electrical noise: ecogNotch In the case below I can effectively filter out the line noise with a notch filter at ...
0
votes
1answer
136 views

Better way to mute fundamental baseband frequency?

I'm working on a project to monitor the fluctuations and harmonics present on standard 120VAC mains power. I built an adapter that drops the voltage from 120VAC to 12V and then down to 0.5-0.6 VAC ...
2
votes
1answer
159 views

Doubts about Notch filter design

I am following the process that is described in this question: Transfer function of second order notch filter , I want to create a notch filter with the band suppressed equal to $f_c = 4000$ Hz, so ...
1
vote
2answers
86 views

Cross-correlation of maximum length sequence with noise

Background I am using a maximum length sequence to find the impulse response of a linear system. I want to calculate the expected SNR. I know that my signal amplitude is scaled by the length of the ...

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