# All Questions

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### Structure of the inverse of the PSD of an autoregressive model

Let a (scalar) autoregressive model of order $p$. It is completely described by its power spectral density whose inverse has a particular structure: it is banded with a bandwidth equal to the ...
2answers
10 views

### Sudden loudness changes producing unwanted noises?

What's that effect called? Is that one of the reasons for having attack and release parameters when implementing synths? And is there a generic method to avoid such sound artifacts? Example: I have ...
0answers
14 views

### Matlab and R functions for fft()

In MATLAB, Y = fft(X,n,dim) returns the Fourier transform along the dimension dim. For example, if ...
1answer
18 views

### What is Imaginary in Fourier transform?

How to plot graph of $e^{-t}$ in frequency domain. What would be the axis? If its Fourier transform is $1 /(1+j\omega)$, then how can we plot imaginary on frequency domain (amplitude vs frequency ...
2answers
40 views

### Explain Auto-Tune in a simple way

I have to do a presentation about Auto-Tune and its relation to the Fourier transform. What is a good explanation on how does Auto-Tune work?
1answer
43 views

### Prove that, in DFT ,interpolation in time domain is equal to replication in frequency domain

Given: $x[n]$ is an $N$-point sequence whose DFT is $X[k]$ $$x[n]\xrightarrow{\mathcal{DFT}} X[k]$$ then, Prove that: DFT of the same sequence after insertion of $(M-1)$ zeroes between successive ...
0answers
17 views

### Kalman Filter Parameter Definition for Vehicle Position Estimation in Python

I'm relatively new to Kalman filter concepts and I would like to use it for estimating and tracking the accuracy of the position of a vehicle with GPS measurements (As a first step). However, I am not ...
1answer
16 views

### Can't seem to get welch function in scipy work correctly

I'm trying to learn DSP through using Python's scipy package. I have measure some 200Hz signal from a machine. Now I want to inspect the spectral density of the signal. Here's the signal plotted out: ...
0answers
9 views

### Error in using Kalman Filter for 2D Position Estimation in Python

This is my first question on DSP Stack exchange, so I apologise if it is poorly worded. I have some positioning data from a vehicle (GPX Format, collected through Strava) and want to use a Kalman ...
0answers
17 views

### RRC filter or rectangular pulse shaping filter in LFM chirp signal

I am working with a LFM up chirp signal, and I wanted to embed some data on it using a BPSK constellation. My doubt was, ¿should I use a RRC filter, like in usual communications schemes, or should I ...
0answers
35 views

### How to distinguish two types of signals

I have two signals , i am trying to find out which signal characteristics can distinguish these two signals.Time series signals:
1answer
12 views

### External/Internal Description of a System

When an LTI system is NOT completely controllable/observable, does the linear differential equation governing the system give the internal or the external description of a system?
0answers
21 views

### Base-band communication [on hold]

Discuss how the parameters fidelity, bandwidth, and time delay can be traded off when Pulse Code Modulation is used for digitizing analogue information.
0answers
7 views

### Inconsistant Variation in BLE Beacon RSSI Values for Distance Measurement

I am developing an application to estimate the distance to a BLE Beacon using its RSSi values measured from a Mobile Phone. But when I started to collect data I could see that they varied so much that ...
2answers
40 views

### Matlab IIR cheby2 bandpass, problems with Magnitude

I am trying to implement an IIR bandpass in Matlab. There are two things I don't understand. But first of all, let me post the code. ...
0answers
22 views

### Localized Gamma Correction

Question: Is there an algorithm that does (what I would call) "localized" gamma correction? That is, applying different gamma corrections on different parts of an image, using a masking filter or ...
1answer
13 views

### Impulse response of a 3x3 PSF - how to find analytical expression for fourier transform of a 3x3 matrix?

I have a filter $\mu[n_1, n_2]$ with taps: $$(1/8) (1/4) (1/8)$$ $$(1/4) (1/2) (1/4)$$ $$(1/8) (1/4) (1/8)$$ How do I find an analytical expression for $\hat\mu(w_1, w_2)$? Since it looks so ...
1answer
35 views

### Why does my sinusoid look “AM” in shape?

My code is : Fs=200e6; Ts=1/Fs; NFFT=2^14; Runtime=(NFFT-1)*Ts; t=0:Ts:Runtime; f_in=90*1e6; y_in=sin(2*pi *f_in *t); plot(t,y_in) ylim([-1.5 1.5]) Then why does ...
1answer
18 views

### Matlab applying an FIR filter to a signal, generated in Matlab

I want to create an FIR in Matlab and apply it to a signal (also generated in Matlab). You will find the code below. I will put my questions in order from here. 1) The filter coefficients vector "b" ...
0answers
16 views

### MATLAB Simulation of LTE Rate matching

Iam trying to simulate LTE Turbo coding/decoding and rate matching/dematching on a binary sequence of 6144 in length using MATLAB. However, when the code rate exceeds 1/3 by a little (say 0,5 for ...
0answers
27 views

### Matched Filter design

When we have to take a decision (is there a target or not using a radar or sonar) or is the received message is “on” or “off” in the case of digital transmission, we do a choice. When the choice has ...
0answers
33 views

### The concept of Auto-correlation and its application [on hold]

Explain the concept of auto-correlation and describe one application of auto-correlation.
0answers
10 views

### Proximal operation evaluate at different point

I have a question: Consider we have the following procedure: $$z = \text{prox}_{\lambda r_1}\left(x - \nabla f(y)\right)$$ In which $r_1$ is just a simple convex function, for example, $\|\cdot\|_1$....
2answers
48 views

### Is the typical implementation of low pass filter in C code actually not a typical low pass filter?

Quite often in C code you see something along the lines of: $$y = (1-a) y_{prev} + input * a$$ ..where $a$ is some small number. This equation then runs in discrete intervals at the loop rate. ...
3answers
47 views

### Power of summed signals

Pretty much a newbie here, but would like to understand a pretty basic concept. We all know that a quick and dirty way of calculating signal power of a part of a discrete sampled system (such as ...
1answer
35 views

### Methods to evaluate the quality of an IIR Filter fixed-point implementation

I'm implementing a scattered look-ahead IIR filter in Matlab/VHDL, basically I convert an order-2 IIR filter into an order-4 IIR in order to take advantage of the pipelining of an FPGA. (reference ...
0answers
22 views

### Capacity achieving codes for BPSK at low SNR

I don't know a lot about comm system design. I have an AWGN channel and low SNR (-3dB). Bandwidth is constrained to some maximum, B. I would like to know good choices of modulation and coding to ...
0answers
13 views

### Doppler Spread and Doppler Spectrum

I am a bit confused about Doppler spread and Doppler Spectrum. I believe the Doppler spread is related to channel coherence time T_c, so that . Due to inconsistencies and incoherency of the channel, ...
2answers
27 views

### Downsides of higher order filtfilt's

I understand that with a standard filter, higher order will yield sharper frequency selection at the cost of increased phase delay. However, with so-called zero-phase-distortion filters like that ...
0answers
20 views

### Avoiding transients during filtering: Padding or Gustafsson's method?

I'm pretty uneducated when it comes to filtering, more of a stats guy, but I have to bandpass some signals and after a bunch of reading today I understand that the ...
1answer
44 views

### STFT on time varying signal with good time and frequency resolution

I am trying to determine the main frequency of a noisy signal that varies in frequency over time. Ideally I want to detect changes in the frequency as rapidly as possible - say 50Hz update rate, but I ...
0answers
10 views

### Which channel is the suitable channel for the short distance?AWGN?rayleigh or rician channel?

What is the unsuitable channel for the short distance?The short distance i mentioned is 1m or 2m.Unsuitable channel I mean is that if i assume this channel in my system,it will be very strange. In my ...
6answers
4k views

### Is there any practical application for performing a double Fourier transform? …or an inverse Fourier transform on a time-domain input?

In mathematics you can take the double derivative, or double integral of a function. There are many cases where performing a double derivative models a practical real-world situation, like finding the ...
0answers
14 views

### Volterra 2nd order kernell convolution

Let say, I can represent a nonlinear model using 2nd order Volterra formulation. I retrieved the 2nd order kernel from consecutive impulse response function (the deviation from the superposition ...
1answer
19 views

### Aliasing correspondance with respect to DFT

Given a sampling frequency Fs lets say we plot the magnitude of the fft of a temporal signal $x$, for different frequencies above the Nyquist frequency, to show the effect of aliasing: ...
1answer
26 views

### Combining compressed measurements from the same source

Suppose I want to measure a signal $x \in \mathbb{R}^n$ subject to i.i.d. noise $\epsilon$. In traditional Nyquist Sampling, I can increase my signal-to-noise ratio by measuring $x + \epsilon$ for $k$ ...
0answers
8 views

### Obtain points in signals which cause correlation

I've got two large .wav files (tens or hundreds of minutes each). I know that at some points these files contain very similar areas - actually, these areas are the ...
1answer
13 views

### Arbitrary shaped RIR generator

I wish to simulate some sound sources convolved with a Room Impulse Response (RIR) and impinging on a spherical microphone array. I could find a couple of generators online (such as this one), though ...
0answers
36 views

### Two versions of Constant Q Transform (CQT) doesn't match each other?

To my knowledge, there's two major CQT papers, the one by Brown in 1991, and the one by Schorkhuber in 2010. The 2010 paper claims to be a more computationally efficient implementation of the 1992 ...
0answers
9 views

### What is the different of Maximum Aposteriori Probability (MAP) method and image registration with reconstruction in multi image super resolution?

I am working on multi image super resolution (MISR) for thermal imaging. I have read several papers and slide about it but there are some confussions. First, I know that the basic of MISR is combining ...
0answers
14 views

### Estimate peak bandwidth from adjacent STFT bins for notch filter

I am using STFT to extract a strong, frequency varying signal from a continuous set of digital samples. I am able to do this very successfully and am determining the peak bin using PSD and 50% overlap ...
2answers
30 views

### Why there is error between My DFT and built in Matlab FFT?

I'm trying to implement DFT/IDFT and FFT/IFFT in Matlab and C. I got wrong values while I implement IDFT/IFFT. So I'm trying to find a mistake. Just for DFT, I used this algorithm to implement it in ...
0answers
4 views

### Measures of edge image continuity and connectivity

Suppose I have a scalar image $I:\mathbb{Z}_{1,m} \times \mathbb{Z}_{1,n}\rightarrow [0,1]\subset \mathbb{R}$, where $\mathbb{Z}_{1,m} = \{1,\ldots, m\}$. (For instance, computed as the (scaled) ...
1answer
41 views

### Automotive Audio Question: IIR Filters and minimum phase

In a car, does matching the EQ of both the left and right side using IIRfilters mean that I'm matching the phase of each side? I have someone telling me that the car's environment is mostly minimum ...
1answer
14 views

### How good is the Leech lattice for AWGN coding or MSE quantization of Gaussian sources?

Anyone know where to find graphs showing how well it works vs other schemes? thanks
0answers
28 views

### FFT Amplitude Resolution

What's the relationship between sample rate, sample length, ADC quantization, and FFT output amplitude resolution? Suppose I have N samples, sampled at Fs such that I can use a radix-2 FFT. My ADC ...
0answers
20 views

### What is the best way to separate data using compressive sensing?

In the book Compressed Sensing by Kutyniok et al, the author talks about data separation using sparse representation. In summary, if we have a signal vector $x = x_1 + x_2$ Then, it would be ...
0answers
23 views

### Deriving transformation from input and output images

I will preface this by saying that my undergrad signal processing course is very far back... Context: I am comparing images of global illumination (GI) passes. I want to be able to change the ...
0answers
32 views

### Delay of non-polyphase vs polyphase FIR filters

I implemented a polyphase filter function for interpolating and decimating. It works great (I compared it to what I'd get by interp/decim by inserting L-1 zeros and I get the same results) except for ...
2answers
27 views

### Help regarding property of unit impulse function

We know that using properties of unit impulse function it can be shown that $$\int_{t_1}^{t_2} x(t) \delta^{(n)}(t-t_0) dt=(-1)^nx^{(n)}(t_0),\quad t_1<t_0<t_2$$ (source: Continuous and ...

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