Questions tagged [signal-analysis]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
3
votes
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 ...
7
votes
3answers
3k views

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 ...
1
vote
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 ...
0
votes
0answers
110 views

How to remove echo/reflected-sound caused by stationary objects when building a ultrasound based radar

I am emitting ultrasound with a speaker and am trying to track moving objects with a microphone array by detecting doppler shifts. I have succeeded to detect movement. However, to detect the direction ...
0
votes
0answers
20 views

Circular queue to use signal processing

How can I forward real time audio samples to different client for further analysis using circular queue in python.
-2
votes
0answers
13 views

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.
0
votes
2answers
140 views

why is my FFT magnitude of real time recording so volatile?

My goal is to do spectrum analysis of a gear motor. I used Python with the Pyaudio package and made a crude spectrum analyzer that displays the FFT as the sound is being recorded. I recorded 10 ...
0
votes
0answers
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
votes
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 "...
2
votes
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. ...
2
votes
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 ...
1
vote
2answers
367 views

Compensation for Irregular Time Step for DFT (FFT)

I want to run a clustering algorithm (svm, knn) on the ferquency spectrum data of a temperature sensor that published at irregular times. Here is the temperature data to take the FFT: I got the ...
3
votes
2answers
1k views

Frequency Analysis of a Signal Without a Constant Sampling Frequency (Non Uniform Sampling in Time Domain)

I'm a stack exchange user for some time and now I'm registering to ask a simple question (I think!). I have a vibration signal with an amplitude and time (sampling frequency not constant) in a $...
0
votes
0answers
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. ...
0
votes
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,...
0
votes
1answer
54 views

What are some of the disadvantages of parametric PSD estimation methods?

Roughly speaking, the methods of power-spectra estimation can be divided in two categories : parametric and non-parametric. From what I understood, parametric methods assumes that the signal can be ...
0
votes
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 ...
1
vote
1answer
155 views

Is convolution distributive over multiplication?

Is there any formula or expansion for $$a(t)*[b(t) \cdot c(t)]$$ $$a(t) \cdot[b(t)*c(t)]$$ where $*$ denotes the convolution? By expansion I mean something like $a(t)\cdot[b(t)+c(t)]=a(t)b(t)+a(t)...
0
votes
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 $ ...
0
votes
0answers
17 views

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 ...
0
votes
0answers
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 ...
0
votes
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.
2
votes
1answer
56 views

Multiply signal $x[k]$ with $\cos(2\pi\nu_0k)$, then given $X(\nu)$ draw resulting function in frequency domain?

Let $$y[k]=x[k]\cdot \cos(2\pi\nu_0k) .\tag{1}$$ Then, given a signal $x[k]$ with the DTFT $X(\nu)$ according to the following figure what will the frequency domain for $Y(\nu)$ look like for a ...
0
votes
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 ...
0
votes
2answers
99 views

negative value of signals

can we say there is no sound produced when the amplitude is 0? if yes what can we say when the amplitude is negative?
0
votes
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 ...
0
votes
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 ...
0
votes
1answer
44 views

SNR of a pulsed signal in noise

I have a digitized acoustic data of length L in which a pulsed signal (chirp) of finite duration and bandwidth is merged starting at some time instant t1 and ending at time instant t2. I wan to ...
2
votes
2answers
138 views

Periodicity of sum of discrete signals

In my lecture slides for school and from this website here "The sum $z[n] = x[n] + y[n]$ of periodic signals $x[n]$ with fundamental period $N1$, and $y[n]$ with fundamental period $N2$ is periodic ...
0
votes
0answers
12 views

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 ...
0
votes
1answer
48 views

EEG Sampling, Which Order should cover my result?

I have EEG data sampling rate is 250 Hz and I want to band pass this data in ( 0.5-3 Hz & 3-8 Hz & 8-13 Hz & 13-30 Hz & 30-40 Hz). Currently, the data is in the frequency range of ...
0
votes
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 ...
0
votes
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 ...
1
vote
1answer
187 views

Are resolution increase and noise reduction from oversampling mutually exclusive?

Oversampling a signal means sampling it with a significantly higher sampling frequency than the Nyquist rate. As far as I know, there are three advantages: Easier design of anti alias filter Increase ...
0
votes
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 ...
0
votes
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 ...
0
votes
1answer
86 views

Down sampling an EEG signal

I have a set of 10 minute EEG signals that were sampled at 400 Hz and have 16 channels which corresponds to a 16x240000 matrix. These EEG signals belong to two different classes. I am trying to ...
2
votes
3answers
1k views

How do you save/convert an image to be in the frequency domain?

Quick Note: I don't believe this is a subjective question... however if it is I will gladly modify to be more objective In ImageJ, if I take the FFT of an image, how can I save this new frequency ...
1
vote
1answer
135 views

Significance of sequency ordering in Walsh-Hadamard matrices

So I've been doing some reading into Hadamard and related matrices (Slant, Walsh, , and have observed that there are three typical "orderings" of the rows based on various criterion. E.g. "Natural", "...
0
votes
0answers
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?...
0
votes
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, ...
0
votes
0answers
17 views

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 ...
1
vote
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 ...
1
vote
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 ...
0
votes
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 ...
0
votes
0answers
9 views

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 ...
0
votes
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 ...
0
votes
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
0
votes
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 ...
1
vote
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 ...