# Questions tagged [signal-analysis]

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### 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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### 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 ...
29 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 ...
102 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?
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### 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 ...
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 ...
161 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 ...
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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 ...
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 ...
33 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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### 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 ...
226 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 ...
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 ...
57 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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### 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 ...
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 ...
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### 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?...
13 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, ...
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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### 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 ...
41 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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### 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 ...
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 ...
18 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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### 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 ...
57 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 ...
47 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 ...
9k views

### Calculate and interpret the instantaneous frequency

I'm new to the principle of calculating the instantaneous frequency, and came up with a lot of questions on it. You find them all in a bullet-point list at the end of this text. The text might be a ...
71 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 ...
106 views

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### Similarity in signal plots but dissimilarity in sensed content

I have two audio signals that look incredibly similar when plotted. However, when I play them, they sound quite different. The only difference I can even see in their plots is that one signal looks ...
396 views

### Why the energy is a good feature extraction for detect disturbances in signal processing?

To detect disturbances in signal processing a common step is to extract signal characteristics to analyze them, among these characteristics it is recommended to use the signal energy. Why energy is ...
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. ...