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Questions tagged [discrete-signals]

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

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1answer
3k views

Converting from stereo to mono by averaging

Hi I'm doing a past exam question about converting from stereo to mono. The scenario is below: The first question is: Explain why would this result in a noisy encoding. How is the noise introduced ...
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0answers
271 views

Complex Demodulation (CDM) and Fixed Frequency Complex Demodulation (FFCDM)

I do not quite understand the difference between the CDM and FFCDM. How can I implement CDM in a program?
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0answers
60 views

How to analyze a pattern of discrete events belonging to a 24 hour and ~90 minute cycle?

I'm a sleep researcher and since last december I've been collecting data on mydreaming and awakening in the middle of the night. Dreaming occurs within a well-known 80-120 minute "cycles", with ...
6
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3answers
8k views

Demonstrating the effect of aliasing

How does the signal look when we don't use the Nyquist rate to remove aliasing from a signal during sampling? Let's suppose the signal is sinusoidal, with a frequency of 500 Hz and an amplitude ...
2
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3answers
11k views

If Digital Signal has frequency components then why we don't use it

As we know there are two kinds of signals: analog signals and digital signals. And there are two common techniques for multiplexing the signals: Time Division Multiplexing (TDM) and Frequency ...
7
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1answer
5k views

Questions about discrete signal energy calculation

I'm looking at the definition of signal energy (e.g. Wikipedia, cnx.org). For discrete signals, it's defined like the following, where $x(n)$ holds the signal: $ Energy = \sum_{n=-\infty}^{\infty} |...
3
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0answers
104 views

Finding the output for an input sequence

So I think I have the answer I just want to make sure I'm doing things correctly. Let a be in the open unit disk, $F_s > 0$, and $0<f_0 < \frac{F_s}{2}$. Let $h[n]=0$ for $n < 0$ and $h[...
3
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4answers
503 views

Implementation of wideband beamformer for planar array

I would like to obtain a good reference (or references) on the implementation of a wideband beamformer for a small planar (rectangular) array comprised of 4 rows by 6 columns, for 24 elements in total....
4
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1answer
1k views

How does causality (i.e. unit step) affect the DTFT of a sine or cosine wave?

Tables of common Discrete-Time Fourier Transform pairs list the transform of a sine wave: $ \sin(\omega_0\ n) $ and its transform: $ -j\pi\ [d( \omega\ - \omega_0\ ) - d( \omega\ + \omega_0\ )] $ ...
9
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1answer
1k views

What is the difference between normalized peak of correlation, versus peak of correlation divided by its average?

Given a template, and a signal, the question arises as to how similar the signal is to the template. Traditionally a simple correlation approach is used, whereby the template and a signal are cross-...
5
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4answers
6k views

Calculate Phase angle between two signals i.e. digital Phase meter

I want to calculate the phase difference between the two channels(signals) of a stereo audio file.(uncompressed data i.e. PCM samples). I want to determine whether whether two signals are in phase or ...
3
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2answers
6k views

what's the baseband FFT size of LTE?

In standard of 3GPP LTE physical layer(3GPP TS 36.211), the FFT size for baseband signal generation for both Dl and UL is 2048 and CP size is also determined. However there is a table in several ...
5
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2answers
948 views

How to remove a tone/interference from a signal, without using classical linear filtering

I am wondering if a methodology(ies) exist for essentially 'filtering' out a tone or interference, WITHOUT resorting to classical linear filtering techniques. (band pass filter, etc for example). ...
5
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1answer
5k views

How can I calculate the Expectation for a particular known vector?

Let us say I have a row vector $X = [x_1, x_2, x_3, \ldots, x_n]$ and another row vector $Y = [y_1, y_2, y_3, \ldots, y_n]$. I want to check whether the two vectors are statistically independent or ...
3
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2answers
471 views

With respect to the dirac delta function, what does $\delta [x + 2A, y - A]$

I have come across the following function and I'm trying to figure out what it really is. I have this function: $f[x, y] = \delta [x + 2A, y - A] - \delta [x - A, y + A]$. The $\delta$ is ...
4
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0answers
106 views

Capacity of channels with pilots?

Question is about "channel capacity" http://en.wikipedia.org/wiki/Channel_capacity I guess it is pretty elementary for experts, however I have not seen it discussed in e.g. Proakis book or Tse "...
6
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2answers
3k views

MOD-N Circular Convolution

How to find MOD-2 Circular convolution for the two sequences $h =[-1,3,-2,1]$ and $x = [1,-1,-2,1,3,2,1,2]$. I know the answer is $7$ $0$ from matlab but I don't know how to find it graphicly or ...
7
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2answers
233 views

Black box signal prediction

I have a stateful black box with four real-valued inputs and one real-valued output. My problem is to predict the output at each moment in time, given the sequence of inputs seen up to that point. ...
-3
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1answer
259 views

How Can I practically implement the FFT with size unequal to a power of two?

Can anybody explain how I can implement the Fast Fourier Transform (FFT) of length unequal to a power of two in hardware, e.g. FPGA? What is the algorithm for this implementation? Does anybody know ...
2
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1answer
246 views

Are there any good “conceptual distances” for comparing two images?

I want to define some distances to use over an image, which I create. I think I need to define two different "distances". The first distance should be the most robustness preserving in compare to ...
1
vote
2answers
865 views

How can I implement a binary chirp signal containing zeros and ones?

I build a signal, $x$, which is linear in the frequency domain as (in MATLAB syntax) x = 1:0.1:1e3; Then I do: ...
7
votes
3answers
10k views

What are high frequencies and low frequencies in a signal?

I'm new to signal processing. I'm plotting a signal in the time-domain in matlab. I don't understand which parts of the signal are high frequencies and low frequencies, can someone explain what a high ...
8
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1answer
2k views

Apply wavelet transform to analyse EEG signal

I would like to apply The Morlet wavelet transform to analyse my EEG signals. I have many short signals each is only 1 min long. and they all recorded in 30Hz. I have Two questions: In the Morlet ...
3
votes
1answer
71 views

How to convert A/D data to the needed representation

I have an Analog-Digital Converter used for getting digital data from LoadCell scales. In order to use this data in my formulas I need to convert that data to the millimeters. But how do I do it?
4
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0answers
143 views

Discrete-time model of 2-user CDMA system, recovered information at receiver using polarity detection?

I have discrete-time model of 2-user CDMA system with: $b_1=-1, b_2=+1, \alpha_1, \alpha_2, s_1, s_2$ and $n$ white noise. What are the recovered infromation bits for user 1 and user 2 respectively ...
9
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1answer
9k views

How does the $\mathcal Z$-transform's “region of convergence” work?

I'm a novice in DSP and I have few doubts regarding the $\mathcal Z$-transform and its region of convergence (ROC). I know what a $\mathcal Z$-transform is. But I'm having trouble with understanding ...
6
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0answers
167 views

EWMA based differential that is strictly positive on strictly increasing irregular time series?

Let's say I have a time series $ \{t_i, x_i\} $ where the $x_i$ are strictly increasing and the $t_i$ are not regularly spaced. I can define a differential operator as $$ \Delta_i = \frac{x_i-x_{i-1}...
5
votes
4answers
243 views

Chopping up and averaging a signal

I have a 1D signal that is roughly periodical (but not exactly) - think of some kind of motion that someone performs repeatedly, and which is measured by some sensor. I am looking for a way to ...
16
votes
1answer
798 views

Is wavelet analysis useful for 1D signals?

Wavelets seem to be very useful for image processing. Assuming that I'm only ever going to study signals of time, i.e. 1D signals, should I still take a course in wavelet analysis? Are they applicable ...
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1answer
500 views

How to do scaling in fixed format?

In my project, the ADC is an 16-bit unipolar type, 0 - 3.3 V. This 16-bit data we are making as bipolar ($-1.65$ to $+1.65$ range), converting as Q15 data. The conversion is as follows. ...
13
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1answer
577 views

Where did Arnold Tustin first introduce the bilinear transform?

It's well known that the bilinear transform is also known as Tustin's Method. As far as I know, Arnold Tustin really did introduce the idea into the control systems literature, so the name isn't just ...
6
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3answers
7k views

RMS calculation in frequency domain after windowing

I can calculate RMS in frequency domain as derived from Parseval's Theorem. But what if I have applied a windowing function before doing the FFT (in my case a Hann window)?. Now the RMS values are ...
13
votes
1answer
6k views

Getting loudness of a track with RMS

I'm trying to calculate the loudness of an audio track I have stored in a buffer. The buffer contains PCM data of the signal and I want to get how 'loud' it is by using Root Mean Squared. I assume I ...
4
votes
1answer
165 views

Find the relation between two noisy periodic signals of equal length

[Thank you, @leftaroundabout for your helpful comments to my related question. I'm trying to ask a less confusing question here.] $0\leq\phi\leq 2\pi$ is a parameter that theoretically describes a ...
7
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3answers
1k views

What is the effect of aliasing on the magnitude of the autocorrelation?

I've a question about the effect of aliasing on the magnitude of autocorrelations. From a simulation in MATLAB, I don't see any effect of aliasing or any need to anti-alias filter when I take the ...
25
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2answers
3k views

Are there alternatives to the bilinear transform?

When designing a digital filter based on an analog filter we usually use the bilinear transform. To approximate a discrete transfer function $D_a(z)$ from analog (continuous) transfer function $A(s)$ ...