All Questions
27,129
questions
0
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0
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3
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First-order allpass filter coefficient calculation
Given the first-order IIR allpass filter depicted below, I would like to calculate the coefficient $a_1$ such that a phase shift of $\frac{\pi}{2}$ occurs at a desired frequency $f_\mathrm{c}$ (the ...
2
votes
0
answers
9
views
HSI formula inconsistency in Gonzalez & Woods
I'm confused about how the book Digital Image Processing by Gonzalez & Woods explains HSI model. It includes a double cone-shaped space for the model (like the figure below) and says every color ...
- 33
1
vote
0
answers
13
views
Early-Late TED in SDR
I am reading about Early Late TED from "Software Defined Radio using Matlab & Simulink and the RTL-SDR". This is from the book:
Now I'm trying to understand the 11.7 formula in a 'for ...
- 11
3
votes
1
answer
69
views
Why is the CT inverse Fourier Transform also an integral?
Intuitively it seems that to get a function back that was integrated, you would take the derivative. Instead, with the Fourier Transform we take an area under a curve of a modified function, and to ...
- 51
0
votes
0
answers
17
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How can i do a horizontal compression of my frequency spectrum for pitch modification
I am working on a dsp project inorder to make a male voice more feminin and vice versa and yes I know there are multiple layers for this but i am focusing on pitch now and later I will move to ...
- 1
0
votes
0
answers
13
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How to impose power constraint on an encoder's output while training a deep NN?
A deep encoder which takes in a 4 bit input gives out an 8-dimensional vector. If I want the power of this 8-D vector constrained to be 1, then I should multiply all the elements by A/B? Where A is ...
1
vote
0
answers
16
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implement gradient descent with sparsification algorithm
I am trying to implement the algorithm in this paper for finding a sparse vector x that minimizes the square error $\lVert y − \Phi x\rVert_2^2$ where $\Phi$ need to satisfy the restricted isometry ...
- 145
1
vote
1
answer
37
views
Is this FIR filter considered symmetric?
My goal is to generate linear phase FIR filters. Currently, I am generating an array of frequency response magnitudes for the positive frequencies and then I mirror those with the complex conjugate. ...
- 298
0
votes
1
answer
22
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What is wrong with this FM synth implementation?
I'm trying to get an FM synth to work, the synth uses wavetable oscillators, I am adapting the formula for FM synthesis:
$$
FM(t) = A \sin(\omega t + B \sin(\omega_m t))dt
$$
To use wavetable ...
- 101
1
vote
1
answer
47
views
Power Spectral Density and Total Power Calculation for Signal
I am currently working on analyzing a signal with the autocorrelation function given by:
$$R(\tau) = 100 \cos( 10000\pi\tau) (Λ(2000\tau))^2$$
I need assistance in plotting the power spectral density ...
1
vote
0
answers
40
views
Spectrum and Fourier transform of a sine wave
Take for example: $x(t)=A\sin(2\pi f_0t)$. The Fourier transform of this signal is $\hat{s(f)}=\frac{A}{2i}(\delta(f-f_0)-\delta(f+f_0))$. If we want to represent the spectrum of the signal we would ...
- 11
3
votes
1
answer
95
views
Audio EQ Cookbook Stability
I'm implementing 6 cascaded biquad peaking filters to make a 6-band EQ. In the system I want to calculate the coefficients on the fly (it's just gain thats changing, center frequency and BW aren't). I ...
1
vote
0
answers
38
views
Help with Implementation of Communication System and Understanding Frequency Response in Python
Professor gave us task to implement communication system as in picture
Communication system is made for the transmission of 32 frequency-multiplexed analog signals through a communication channel. ...
- 11
1
vote
1
answer
39
views
Resolution after Oversampling, Filtering-Decimation
The ADC I am working on has a resolution of 24 bits and a Signal-to-Noise and Distortion (SINAD) of 108.4 dB. Assuming only quantization noise is present, the Signal-to-Noise Ratio (SNR) of the ADC ...
- 21
0
votes
1
answer
30
views
What is the denominator of the transfer function when PI-regulator is connected?
A system is described by the transfer function
$$G_p(s)=\frac{s+2}{(s+1)(s+3)}.$$
A PI-regulator is connected to the system making it a closed loop system.
So the transfer function for the PI-...
- 101
0
votes
1
answer
41
views
Calculate Total Harmonic Distortion (THD) from FFT Plot
I am new to FFT and currently studying it for harmonic analysis. I have a set of data of inrush currents from the results of simulation involving equipment energization. The data has $N = 40,001$ ...
0
votes
1
answer
39
views
Why is my FM synth getting out of phase?
I'm trying to create a software FM synth following the formula for frequency modulation:
$$
y(t) = A \cdot f_c(t + I \cdot f_m(t))
$$
Where $A$ is amplitude, $f_c$ the carrier function, $f_m$ is the ...
- 101
1
vote
1
answer
30
views
output of CIC filter is scaled by what frequency?
Suppose I have a CIC with a down sampling rate $R$, differential delay $M$, and number of sections $N$. My sample rate is $F_s$.
If I pass a signal through my CIC I will down sample by $R$. If I plot ...
- 31
0
votes
0
answers
22
views
EIRP for JWST HGA
I am attempting to compute the EIRP for transmissions from the James Webb Space Telescope using the high-gain antenna. I found the following reference...
https://www.ioag.org/Public%20Documents/2019-...
- 63
0
votes
0
answers
38
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Separating 'heart sound' from 'lung sound'
I have audio files recorded from electronic stethoscope and in those files I want to filter out heart sounds and retain just the breathing sounds. How can I do this using just the signal processing ...
3
votes
2
answers
62
views
Why not overlap save for inverse stft
Since STFT uses overlapped sections of the input signals and compute DFT, it resembles overlap-save method used for block convolution, instead the overlap-add method for block convolution uses non-...
- 31
0
votes
0
answers
23
views
Z Transform and Difference Equation [closed]
Given that
$$H(Z) = 4z+2/(4z^2+2)*(2z-1).$$
Find the difference equation of g(n) such that g(n) and h(n) are two cascading filter such that output is same as input. Moreover find the frequency ...
0
votes
0
answers
18
views
Looking for paper about applications of using phase screen to model space laser communication
A phase screen is a concept used in wave optics to model the statistical properties of wavefront aberrations caused by a medium. In the context of light propagation through atmospheric turbulence, for ...
- 178
12
votes
3
answers
2k
views
Why is the time domain low-pass filter the "sinc" shape?
Consider:
I'm looking at low-pass filters, and I see that the time domain representation of an "ideal" filter resembles the shape above whereas the frequency domain is a box. I also get the ...
- 123
1
vote
0
answers
15
views
Confused About Relationship Between Number of Points and Solving Wiener Filter Coefficients in Time Domain vs Fourier Domain
I'm interested in computing M, FIR filter taps / coefficients using a Wiener filter approach with known signal and noise timestreams. I know of two ways to compute the coefficients: one in the Fourier ...
- 11
2
votes
1
answer
64
views
low shelving filter frequency response diagnosis
I am building a second order modified biquad filter based on an implementation by Will Pirkle in "designing audio effect plugins in c++". However when I look at my implementation's ...
- 133
1
vote
0
answers
52
views
What can be the pole zero diagram [closed]
Does the pole zero plot for $$H(z)=(1-z^{-1})^3(1+z^{-1})^3$$ have 6 poles at origin and 3 zeroes at 1? Just answer yes or no, not your homework question knowledge
- 21
6
votes
2
answers
319
views
Modelling MEMS accelerometer noise
I am trying to compare two MEMS accelerometers in terms of their noise for ground motion monitoring applications. I would like to take some "clean" data (recorded by good quality ...
- 61
0
votes
0
answers
13
views
Computing Channel Power from file containing RMS measurements from tri-axial spectrum analyzer
I have some files from a spectrum analyzer in RMS mode equipped with a tri-axial antenna. I am supposed to compute the channel power evolution for two distinct LTE channels.
I have files containing ...
- 61
4
votes
0
answers
41
views
Discrete Fourier Transform of the Gaussian
Cross-posted from here
I encountered the following question in a Digital Image Processing examination:
Find the 2D DFT of $\frac{1}{2 \pi \sigma^2} e^{-\frac{(x - x_0)^2 + (y - y_0)^2}{2 \sigma^2}}$ ...
- 41
0
votes
0
answers
48
views
padding zeros at the center: where to place the -ve frequencies
There are several thread regarding zero padding at the center and padding at the end.
I have a spectrum and want to interpolate it.
DFT of real sequence: $\left[X_0, X_1, X_2,\dots,-X_2, -X_1\right]$
...
- 655
0
votes
0
answers
27
views
Is there any way of calculating the portion of signal lost as we keep on reducing the passband edge frequency of a band-pass filter?
Any kind of references would be appreciable.
0
votes
0
answers
73
views
Prove the following [closed]
If $$x_1[n]=A$$ where $A$ is a constant, $$x_2[n]=u[n]$$ and $$x_3[n]= \left \{ \begin{array}{l} 1, \mbox{for n=0}\\-1, \mbox{for n=1}\\ 0, \mbox{otherwise} \end{array}\right.$$
Prove that $$x_3[n]\...
- 21
0
votes
0
answers
30
views
Driving bandpass DSM with tone close to full-scale - stability issue?
I am experimenting with Dr. Schreier's DSM toolbox for MATLAB. I stumbled over a strange phenomenon when having a look at a bandpass DSM in demo-script 2. If I increased the amplitude of the test-tone ...
- 413
0
votes
0
answers
14
views
Channel Estimate for OFDM shows distortion for first last order samples
The Channel Gain Estimation was obtained using Least Square method as follows:
Hk= mean(Rx_LTS ./ Tx_LTS, 2); k= -26 to 26
Where Rx_LTS is the received long training sequence (52 samples after ...
- 31
1
vote
1
answer
77
views
Continuous-time convolution of signals with negative amplitudes
While preparing for a mid-term exam, I encountered negative amplitudes for the first time while convolving two signals.
I've already solved the problem, but my result and results from others conflict ...
- 13
0
votes
0
answers
34
views
Calculation of response of continuous-time LTI system [closed]
Consider an LTI system defined by the following impulse response $S_{1}$
$$ h \left( t \right) = u \left(t - 6 \right) - u \left( t \right) \tag{1} \label{1} $$
Assuming $x \left( t \right) = 5 \left[ ...
user70242
3
votes
3
answers
586
views
Help me understand the concept of IQ signals
I am a computer science student working on a school project involving RTL-SDR receivers, and I have a hard time grasping the concept of IQ data. Basically what I think I have learned from all of the ...
- 31
0
votes
0
answers
17
views
Allan variance plot does not match with the true plot
I am trying to simulate an Inertial Measurement Unit (IMU) by generating sample noisy gyroscope and accelerometer data. Currently I am analyzing the simulated gyroscope( gyro)
data. Using the noise ...
- 163
1
vote
1
answer
54
views
How to specify the cut-off frequence in cascaded biquad filters?
As part of my effort to understand how a high-pass filter can be implemented, I'm reading this section of HandWiki.
My question here is: How do the 2 simple formula presented there filter out at a cut-...
- 125
1
vote
1
answer
53
views
Understanding how to implement high-pass filter with cascaded biquad filters
I'm trying to understand how to implement a high-pass filter using, quote:
a cascasded biquad direct form II IIR filter
with a cut-off of 8kHz.
DSP is a complete new field for me, and the ...
- 125
0
votes
1
answer
65
views
Energy and power of time-continous signal $x(t)=t$?
Preparing for my exams, I stumbled upon this particular problem.
I tried to calculate it using following formulae:
$$ E = \int_{-\infty}^{\infty}|t|^2dt $$
Dividing it into two cases because of the ...
- 13
0
votes
0
answers
22
views
Desired trajectory generation from transfer function in control theory
I am trying to implement the backstepping techniques for quadrotor described in this article : Backstepping control for a quadrotor helicopter: Madani & Benallegue 2006
Since I am new to the ...
- 21
1
vote
0
answers
33
views
Testing CNN model using sound generated from pyroomacoustics room simulation
I have generated a large set of audio using Pyroomacoustics for room simulation, employing a circular microphone array and a single sound source.
I have successfully trained and tested a CRNN (...
1
vote
1
answer
77
views
Fourier transform magnitude of the sum of two signals
Let
$$\mathscr{F}\Big\{x_1(t)+x_2(t)\Big\}=X_1(f)+X_2(f)$$
I think that in general
$$\big|X_1(f)+X_2(f)\big|^2\leq\big|X_1(f)\big|^2+\big|X_2(f)\big|^2$$
but I was wondering if
$$X_1(f)X_2(f)=0,\qquad\...
- 31
0
votes
1
answer
37
views
Welch method implementation not smooth
I have been trying to recreate the welch method implemented in scipy.signal by hand but my results don't look close enough in my opinion. How come the scipy.signal.welch method is displaying much ...
- 3
1
vote
0
answers
18
views
please help me solve the question which proving X[N-k] is the complex conjugate of X[k] [closed]
Show for the DFT that if all x[n] are real, then X[N - k] is the complex conjugate of X[k] for k > 0. (i.e. if
X[k] is a + bi, then X[N - k] is a - bi)
- 11
0
votes
1
answer
40
views
Characteristics of linear systems in the time and frequency domain
Why is the output signal obtained through frequency response different from the other two.
...
1
vote
0
answers
61
views
Which filter is suitable for reducing noise in feature detection?
I have a feature detection algorithm that is called FAST - Feature Accelerated Segmented Test.
It's a very fast algorithm for finding feature points, e.g "corners" inside an image. Here is ...
- 403
1
vote
0
answers
23
views
RLS Adaptive Filter for estimating signal
I am currently working on a project where i am to estimate a signal x_T using x_1 and x_2 with an RLS filter.
I have a problem where i don't quite get the results i am looking for. I think there is a ...
- 11