# Questions tagged [discrete-signals]

A discrete signal or discrete-time signal is a time series consisting of a sequence of quantities.

1,453 questions
Filter by
Sorted by
Tagged with
1k views

### Time-reversal and delay commutativity and resulting signals

I'm reading Schaum's DSP book, and in Fig 1-3 they demonstrate why shifting and reversal are order-dependent, showing a couple of simple systems, 1) delay followed by reversal, and 2) reversal ...
748 views

### Pulse detection against various noise floors

I'm decoding a pulse amplitude modulation encoded digital signal. The goal is to detect the individual pulse against a background noise floor. The amplitude of the pulses varies depending on the ...
164 views

### how to detect the center frequency of a QRS complex in an ECG signal?

i want to design a filter that can effectively detect the QRS complex in ECG signal(whose Fs=360Hz) and reduce high frequency noise components. i want to know as to how the center frequency is ...
309 views

### 3D image sample frequency

I am currently frequency filtering a 3D image in matlab, with x,y,z dimensions of different lengths. The matlab filter takes normalised frequency as an argument. What does this mean for an image and ...
3k views

### Matching 2 audio files

I'm doing research on how we can do matching between 2 audio files using Android to see if they have the same content or not. After doing lots of research, I have concluded that I must do 2 main ...
2k views

4k views

### Why convolution is required, or what is the philosophy behind convolution?

I am working in digital image restoration field. I have read all things about convolution, that, for an LTI system, if we know its impulse response, then we can find its output by just using ...
204 views

### How to convert an analog signal to an impulse signal?

I have several analog signals with constant amplitude in time. What I want is a way to convert these analog signals to an impulse signal i.e. a signal that consists of impulses occurring at different ...
206 views

### Is there any way to differentiate between impulses?

I have a set of signals consisting of impulses at different instant of time i.e. its not a continuous signal. What I want is a mathematically intuitive way to distinguish between any two such signals? ...
448 views

### Calculating the Norm of Each Sample of the DFT Trasform

Given a discrete signal $\left\{ x[n] \right\}_{n=0}^{N-1}$ and its Discrete Fourier Transform $X[k] = DFT \left\{ x[n] \right\}[k]$. I'd like to effectively compute the norm of each sample of ...
1k views

### How to Combine Low and High Frequencies of Two Images in MATLAB?

I would like to combine two images A and B in the following way: 1) I want to take a Fourier transform of both of them 2) For image A I want to apply a weighted filter, which gives more emphasis for ...
214 views

### Fitting fixed number of complex exponentials to complex signal

I have a complex data series, and I would like to fit a fixed number (in this case, two) of complex exponentials of the form $Ae^{jBn}$, where A, B are complex. Not interested in the phase (i.e. arg ...
4k views

### How to determine the window size and weights in Weighted Moving Average (WMA), given desired cut-off frequency?

I am trying to smooth my discrete-time data points using the method of WMA. Currently, I am using n as the window size and the weight array, ...
280 views

### Peaking Equalizer

I'm making peaking equalizer in C# using NAudio (EQ-Cookbook). Can anybody tell me what is wrong with this code? It gives me noise. Sliders ...
159 views

### Digital Image Processing Framework

i'm looking for a free/opensource solution for digital image processing with reasonable performances processing quite large images (e.g. actual smartphones have resolutions of 8-10Mpx) and being ready ...
2k views

### Detecting a single frequency in noisy data

I am not very experienced in signal processing, and it seems like this should be a simple problem. I have two computers, one plays a tone a 19 kHz at a sampling rate of 44.1 kHz, and the other listens ...
65k views

### How to apply Hamming Window?

I am new in matlab and signal processing. The time series that have been used are obtained from accelerometer in a building. As far as I understand both the time series' length and window function ...
152 views

### DSP related websites and blog posts [duplicate]

Do you guys know good DSP related websited and blog posts? I know that for example there is this site called Minutify: http://www.minutify.com which is blog posts regarding all areas of electrical ...
3k views

### Power or Energy Signal?

Can you tell me whether the following signal is a energy or power signal? $$x(n) = e^{j (n \pi/2 + \pi/8) }$$ I've solved it and found it as it was neither power nor energy signal was that right?
3k views

### NAudio real-time equalizer

I have designed 9 IIR bandpass filters (chebyshev type 1, order 4) using fdatool in Matlab. Then I use a and b filter coefficients to apply it on differential equation. So, my question is how to apply ...
321 views

7k views

### Simulink continuous to discrete question

I'm new to Matlab/Simulink and would like to convert the continuous system below to discrete for eventual conversion to C code. Matlab has a c2d function, but I don't know how to apply it to a ...
936 views

### Determining the mean of of a sampled signal (improvements to time averaging method)

I am sampling a signal at 1kHz, which is essentially a single-frequency sinusoid with a DC offset (and a small amount of noise). I don't know the precise frequency of the sinusoid (it is at most 10Hz),...
361 views

### Cross Power Spectral Density of Unevenly Sampled Data

Here's my problem. The input signals $x$ and $y$ will be having the time value aligned with each other. However, the data are not evenly sampled. I would like to calculate CPSD of both signals. The ...
341 views

### Kalman Filter: continuous state space, discrete observations

This is just an idea. How can we model the kalman filter to get the state representation in continuous space when the observations to the system are actually from the discrete space. The discrete ...
902 views

### One Source Signal Separation

I have a wav file which is gained by playing 2 different wav files with 2 speakers and recorded with mic. If I want to get one of the original signals using the resulting wav file and the other ...
358 views

### How to automatically detect blurred document images

The question I have is related to image quality evaluation. Suppose you are supposed to perform OCR (Optical Character Recognition) on a set of document images. Some images, however, are very blurring,...
11k views

### How to compute dBFS?

I asked myself how to compute dBFS (dB full scale) from a value of sample between 1 and -1? and in general?
159 views

### Format location from LPC magnitude

I am confusing when I find the lpc roots magnitude, f1=0.9313, f2=0.9308, f3=0.91 and f4=0.95 but when I look at LPC envelope the f1 is higher than f4 in term of magnitude in dB. Could anybody explain ...
127 views

### doing sine regression to recover the paramters from a given signal

I have a discrete signal. I want to do sinusidal regression to estimate the parameters such as amplitude,phase, frequency etc It is important to note I only have the signal values and ...
128 views

### What is the theoretic difference in the ways to compute the spectrogram?

I have noticed that the spectrogram for a audio signal is often calculated in different ways when the result from the DFT is transformed into real numbers; some tend to compute $|k|$ or $|k|^2$ while ...
366 views

### Calculate interbeat intervals

I'm currently reading a paper and I can't seem to make sense of a certain part. A link to the paper: removed The part I don't quite get is on page 286 (after the part where they explain their filters)...
272 views

### Banding in the derivative of a lock-in amplifier signal

I'm analysing several measurements taken with a SR830 lockin amplifier. These measurements look similar to this one. Since I'm interrested in the derivative of the signal I took the numerical ...
11k views

### Finding the dominant tone in a signal

I am given 256 samples at a sampling rate of 48k and am asked to find the frequency of dominate tones and the amplitude of the largest tone. The data looks like this when plotted: I assume I must ...
874 views

### How to calculate the energy levels of frequency intervals of an audio signal?

Using the Fourier transformation I can translate a signal from the time-domain to the frequency-domain. If I divide the frequency axis into intervals, how can I calculate the audios signals energy for ...
1k views

### Determine the type of filter from the transfer function

i got that system $x_n \to x_n-x_{n-1}$, so $h_n=[.....,0,1,-1,0,...]$, with $h_0=1$ and $h_1=-1$, so the transfer function given by: \sum_{i=-\infty}^{\infty} h_ne^{-jwn} = h_0e^{-jw(0)}+h_1e^{-jw(...
932 views

### Are there any measurements or test for whether an audio signal is stationary?

I need to divide an audio signal into frames in which the signal can be assumed to be stationary. How can I measure whether an audio signal is stationary in a frame?