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Questions tagged [signal-analysis]

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with given Sampling rate, what max frequency human voice can be captured?

I'm new to signal processing and sampling rate, I was asked interview question related to this. This is the exact question asked: With 8Khz of sampling rate, whats the max frequency that human ...
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1answer
39 views

Square wave FFT results show frequency that seems too low?

I have created an open source plotting package for a low cost oscilloscope - see link here: GitHub Plotting Software But during my testing I have one result that may be wrong: a noisy 7 kHz square ...
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1answer
35 views

Convolution Integral of Harmonic Signal (Cosine) with the Sinc Function

I was asked to show that this convolution integral results in the answers also given in the image. Not quite sure how to approach this integral, everything seems to be coupled together. Does anyone ...
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3answers
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How can a signal be both periodic and random?

Do any examples of such signals exist where the signal is both periodic and random? Because as I see it, if a signal is periodic then the randomness kinda goes away because you know what the signal ...
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Circular queue to use signal processing [on hold]

How can I forward real time audio samples to different client for further analysis using circular queue in python.
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power spectral density estimation

I have an audio signal carols.wav. How do I obtain the PSD in Matlab using the inbuild pwelch function and also to write my own code.
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7 views

Optimizing a heating/cooling system for a particular input

Lets say I have a house with 2 rooms. One of them has a window that opens and closes T periodically. So the heat influx behavior of the window is like a square wave. There is an air conditioning unit ...
2
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1answer
36 views

Initial Rest Condition for LCCDE causal LTI systems

I am self studying Alan Opennheim's course Signals and Systems. I am a math major and have no background in EE. I understand that for a LCCDE system to be linear its auxiliary conditions must be 0. ...
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27 views

Underwater acoustic channel is giving me a flat BER vs SNR curve

I need to do OFDM and GFDM signal transmission in underwater acoustic channel. I have my underwater acoustic channel as follow. ...
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0answers
11 views

How to do colour map in MRI?

For this question, I assume if we do a colour map, it is based on the magnitude of the magnetic strength? After that how do we know where each coordinates belong to? Like for example at p= 0 degrees,...
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2answers
40 views

Dominant Frequency Peak Decreases with Increasing Window Size

I have a signal that looks like this. I analyse it using fast Fourier transforms to identify the frequency with the largest peak, which is always close to zero. (There are no other clear peaks.) If I ...
2
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0answers
61 views

How does shifting Product/Divide Block work? [migrated]

I've just learned about PID MRAC using MIT Rule, and to build it in Simulink I need to use the Product/Divide Block. https://www.mathworks.com/help/simulink/slref/product.html This is a figure from "...
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1answer
65 views

DC Spur in DAC output

I have a design in which a signal from ADC is filtered and then played by DAC. In FPGA the real signal is converted to quadrature using DDS with 70 MHz frequency. After filtering, the baseband signal ...
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1answer
41 views

Coefficients of the Fourier Series expansion of physical signals having finite power

Question 2.7. Show that for all periodic physical signals that have finite power, the coefficients of the Fourier series expansion $ x_n $ tends to 0 as $ n \to \infty $ I have computed $ |x_n|^2 $ ...
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0answers
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Digital Spectrum Analyzer: Video Bandwidth

I am currently working on a Digital Spectrum Analyzer. We are trying to imitate a hardware Spectrum Analyzer by capturing I/Q data and performing an FFT on it. I am a bit stuck on how to imitate the ...
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54 views

Signal Averaging

Note I also asked this in math stackexchange I was reading a wiki page about signal averaging specifically in the section Signal power for sampled signals. At least at first glance the information ...
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0answers
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Stack features in wakeword model

I'm not clear how is the input features are stacked in wakeword applications. Taking https://static.googleusercontent.com/media/research.google.com/en//pubs/archive/43969.pdf as an example, the author ...
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1answer
60 views

How we can represent a bandpass signal equation in matlab

The general form of bandpass signal is given by $$s(t) = \Re\{S_b(t)\exp(j2 \pi f_ct)\}$$ How this can be represented in matlab.
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1answer
28 views

What is the secrecy rate?

I read several papers on physical layer security that explain several methods to maximize the secrecy rate. However, I didn't find a very clear definition about the secrecy rate. What is it? How is it ...
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1answer
32 views

Finding the phase and frequency of a tone with Doppler. What is wrong in the code?

I am trying to find the phase and frequency of a single tone having a small Doppler (10 Hz). I have the following code. The integration time for the operation (the length of the time vector) is ...
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0answers
21 views

Using a Multirate FFT system to analyse audio

I am trying to implement a multirate fft system to try and achieve frequency windowed analysis of audio. Say I have managed to get an impulse response of a system. This impulse may be say one ...
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1answer
45 views

Frequency-selective channel: Basic in theory

In a lecture, it was covered a topic "frequency selective and flat fading channel models". For case, the frequency selective channel we have a channel impulse response ...
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0answers
12 views

As of 2019, which discrete nonlinear, time-invariant systems with memory are considered “easy” to model and identify?

There are several types of discrete nonlinear time-invariant systems with memory ("NTIM") which are considered "easy" to model and identify. Any such system can be represented using a Volterra series, ...
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50 views

Calculating output of a digital system signal with a filter that introduces delay

We have a step function at the entrance that goes through the following system. The $D(z)$ digital filter introduces a 0.25s delay. Output as $y(kT)$ must be calculated. How can we tackle this problem?...
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performance analysis of channel

I am studying channel precoding, and as HW lab it was given a task to implement a system with different precoding algorithms and to apply an algorithm that was given in lab description. So I have ...
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1answer
58 views

Element-wise powering vs. discrete version of binomial theorem on a sum of Gaussians

I had recently posted a question on applying powers on a sum of Gaussians (here) to enhance signal resolution artificially. The discussion has given rise to another query. Consider this problem. We ...
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2answers
64 views

Applying a Power on a Sum of Gaussians to Enhance Resolution

There is so-called Power Transform technique in signal processing where the unresolved signal is sharpened by raising each data to a constant positive power. The example shown below is a sum of two ...
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1answer
100 views

CIC Filter implementation for Normalized Correlation

This is a follow-on to the original post ... I am trying to implement real-time correlation of two signals. I noticed the CIC Filter discussion here: How to find correlation/cross-correlation of two ...
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0answers
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eqation that describe the effect of negative image on positive image

when we plot the spectrum of an incoherent windowed signal (say we use Hanning window), the bins are spread. My question is how we quantify the leakage effect of negative frequency say at -fo affect ...
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0answers
16 views

interpretation of per survivor processing

Can any one explain me the interpretation of persurvivor processing, and how it is different from mlse,reduced state mlse,decision feedback mlse. What exactly meant by per survivor. Thanks in advance
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0answers
21 views

Z transmittance from diffrence equation made out of diagram

I have a problem with getting Z transmittance out of a single block of diagram, when e(nT) is as an input, and u(nT) is as an output. Period of sampling is T = 0.5 s The diagram is: My first thought ...
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1answer
40 views

DC Components and Frequency

I have started learning digital communication and was on line coding. I read there are certain characteristics that we need to keep in mind while choosing the right line coding method. One of these is ...
1
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1answer
50 views

Why the spectral coherence is unity for all frequencies between single-frequency time series and itself

In the example below, I am plotting the coherence between time series and itself. The time series do has one frequency.The coherence magnitude was one for all frequencies. I wonder why it is not zero ...
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1answer
46 views

Signal processing using numpy python

To process a .wav audio file with numpy (using fast Fourier transform algorithm). I want to process an audio signal at a particular interval with a sampling frequency 44100hz and sampling rate of 20ms ...
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1answer
48 views

Relationship between signal rate, data rate, minimum bandwidth

I need to understand the relationship between bit rate, signal rate and minimum bandwidth. I read in a textbook that We define three cases for relationship between bit rate and signal rate for ...
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0answers
33 views

How to compute properties of a song like key, bpm? [closed]

How to compute the key and BPM of a piece of music? Is the Fourier transform necessary? I tried to approach this issue from the music theory angle and I found that I get stuck at trying to understand ...
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1answer
25 views

Block by block CCDF and PAPR analysis in MATLAB

There are few signals (OFDM-like modulation scheme with uniformly distributed data source) generated by my script. I need to compare scheme performance in sense of CCDF (Complementary Cumulative ...
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0answers
17 views

Detection time of a spur using FFT?

Say I have the following parameters, NFFT=2^14 Fs= 50 MHz main signal @ 22 MHz and its alias at 28 MHz at signal power -40 dbfs and a spur @ 2 MHz and its alias at 48 MHz Leave aside the alias's. ...
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2answers
63 views

use of complex number in digital signal processing [closed]

how complex number used in digital signal processing. detailed information about on how this method will be useful in radar technology.
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0answers
13 views

What features can be extracted from accelerometer sensor used for Structural Health Monitoring (SHM)?

I am using dataset found online for SHM which uses accelerometer sensor to detect changes in the structure. I know that I can transform the time-domain data into a frequency-domain and into a time-...
0
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1answer
36 views

how do I derive the system equation for a simple delay with feedback?

I am a software engineer, and just learning digital signal processing formally, though I've hacked around before a fair amount. I'm implementing a delay audio VST and I'm trying to wrap my head ...
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1answer
57 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 ...
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1answer
59 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 ...
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6answers
5k 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 ...
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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 ...
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0answers
27 views

ACF of $X_t = a + bt$

I was able to prove the following convergence results. But how can we determine the theoretical autocorrelation function of the deterministic sequence $X_t = a + bt$ and $X_t = c\ \text{cos}(\omega t)$...
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1answer
39 views

How to automatically identify a surge in a periodic signal

Say I have a periodic signal i.e. Sine wave, which sometimes can have spikes that are 100% larger than the peak value. These spikes can be periodic as well. I'm trying to find an algorithm that could ...
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3answers
68 views

Can the colors of an image be interpreted as “virtual” Doppler effect? [closed]

In astronomy, the Doppler effect is used to estimate approximate distances to stars and other celestial bodies. Using the same principle, lets say we divide an image (photograph) in pixels and that ...
3
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1answer
60 views

PSD from autocorrelation in MATLAB

I am trying to simulate a simple stochastic process defined by the equation: \begin{equation} \frac{1}{v}\frac{db}{dt} +\Gamma_0 b= \sqrt{\sigma}R(t), \end{equation} where $R(t)$ is a zero-mean white ...
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1answer
29 views

How to calculate this energy for a given signal?

So the question Im asking can be seen in the picture below.The d at the end of the question stands for the minimum euclidian distance. Mostly I just want to know how to calculate the energy for each ...