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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6 votes
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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}...
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5 votes
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92 views

Find moments of a discrete process using $\mathcal{Z}$-Transform method

For a linear process relating a variable $Y_i$ to random, independent variables $X_i$ using the equation: \begin{equation} Y_i = aY_{i-1} + (1-a)X_i \end{equation} which has the solution: \begin{...
4 votes
0 answers
64 views

Block CMA algorithm

The Constant Modulus Algorithm is a common equalization method which adapts at every sample in an attempt to give a filter which produces a fixed power output. Divergence/convergence of the CMA ...
4 votes
0 answers
3k views

Verifying MFCC Final Result

I have created a Octave code for MFCC calculation for speech recognition, which takes a wav file as input and then gives the MFCC as the output. But the final results are a bit confusing, so I am ...
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4 votes
0 answers
123 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 "...
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4 votes
0 answers
152 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 ...
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4 votes
1 answer
89 views

Apple watch measures indoor swim distance despite drift and noise in accelerometer and gyroscope

From my experience and work, I know that getting distance estimates just from accelerometer and gyroscope is an extremely difficult task, especially when you are swimming. I have also seen that even ...
4 votes
1 answer
258 views

New to DSP and having trouble filtering data

I am trying to make program in matlab that counts the number of times the accelerometer was lifted up and down (a rep counter for exercise). Basically my phone is getting accelerometer data on all ...
3 votes
0 answers
41 views

Why is optimal beam-forming vector w orthogonal to channel signature?

I am looking at an online document on optimal beam-forming methods: https://www.comm.utoronto.ca/~rsadve/Notes/BeamForming.pdf (sorry I could not find author info from the pdf). One of the strategies ...
3 votes
0 answers
89 views

About discrete time model for wireless channel

I am trying to understand Section 2.2.3 of the book "Fundamentals of wireless communication" by Tse and Viswanath. In this section the authors explain how to go from the continuous time ...
3 votes
0 answers
544 views

How does image rotation affect the intrinsic camera parameters?

I am considering the problem of how to (manually) change camera model parameter to make it "valid" on a rotated image. This question tackles resizing, but does not consider lens distortion. ...
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3 votes
0 answers
197 views

How to compute (in non adaptative way based on MMSE FIR) the feedback and feedword filter for DFE equalization?

System Model Consider the single-input single-output (SISO) communication system in the figure below: where the information bit stream is encoded and mapped such that the output of the encoder is a ...
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3 votes
0 answers
2k views

4th order cumulant of signal

I'm trying to implement some code for watermarking on audio based on a scientific paper. I'm stuck in the part of the pseudo code where they calculate the fourth order cumulant of the approximation ...
3 votes
0 answers
167 views

understanding discrete wavelets

I was reading section 4.3.3 from chapter 4 of "A Wavelet Tour of Signal Processing", "...Let $\bar{f}(t)$ be a continuous time signal defined over $[0,1]$. Let $f[n]$ be the discrete signal obtained ...
3 votes
0 answers
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 ...
3 votes
0 answers
339 views

Wavelet computation with filter bank - differing results

I'm trying to get a grip on Wavelets. I've read "Wavelets, Their Friends, and What They Can Do for You" which lead me to an implementation of the discrete DWT with filter banks. Basically, I'm using ...
3 votes
0 answers
170 views

Interpretation of a periodogram: the effect of window sizes

I am specifically working on a categorical time series of best n number of parallel threads (for n=1..16) for a multicore workstation. I constructed the Walsh-Fourier periodogram for size 2^10 and 2^...
3 votes
0 answers
819 views

calculate root mean square, ratio of power, constant false alarm, ... of a signal

I am new to Digital Signal Processing, and am reading a paper. I don't know how they can extract some features from signal, like root mean square (RMS), Constant False Alarm Rate - CFAR, Mean Value ...
3 votes
0 answers
63 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 ...
3 votes
0 answers
141 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 votes
1 answer
179 views

Potential issues arising from too stable discretization

When numerically simulating a system, usually some kind of discretization is necessary, obtained by some kind of z-transform, such as, for instance, the bilinear transform $s\mapsto \frac{2}{\triangle ...
2 votes
1 answer
45 views

Need help with DTFT problem

Prepping for exam and this is one of the practice problems: I just want some clarification on some of the steps my professor took. This is the answer in the answer sheet Only thing I dont understand ...
2 votes
1 answer
72 views

N'-band channelizer (filter bank) via Sliding FFT

I'm trying to figure out how to perform N'-band channelizer for SSCA (strip spectral correlation analyzer) via sliding FFT. I understand that I have to take $N$ points of signal in time domain $x(t)$, ...
2 votes
1 answer
180 views

FMCW radar: understanding of doppler fft

I am using fmcw radar to find out distance and speed of moving objects using stm32l476 microcontroller. I transmit the modulation signal as sawtooth waveform and I read the recieved signal in the ...
2 votes
0 answers
46 views

Scatter plot of two signals - Shows independence?

If we have 2 signals, and we want to show that they are independent, I came across a reference where the scatter plot for both was shown, and from the scatter plot, it was written that the signals are ...
2 votes
0 answers
38 views

What is an analysis dictionary or operator in compressive sensing?

I am doing research on compressive sensing. I am new in this field. I read several papers regarding analysis dictionaries. Here are some papers that I have read so far: https://www.hindawi.com/...
2 votes
0 answers
47 views

Adaptive Delta Modulation: Logic for step size control at receiver

I read that in adaptive delta modulation, we have a block for step size control (diagram below) which takes into account the one bit quantizer output in a feedback loop and modulates it, the intent ...
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2 votes
0 answers
133 views

What is the physical significance of statistical quantities like mean, variance, skewness and kurtosis of a digital signal?

I understood the mathematical meanings of the mean, variance, skewness and kurtosis. But when we calculate these quantities for a signal (say a digital audio signal), what physical meaning do they ...
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2 votes
0 answers
232 views

Lagrange Vs Sinc interpolation

I was wondering what is the practical difference between Lagrange Interpolation using Farrow Structure and Sinc Interpolation? Both require pre-computation of time offset coefficients using a lookup ...
2 votes
0 answers
348 views

Understanding and converting Matlab's coarse frequency compensation function

I am trying to understand and convert to C Matlab's coarse frequency compensator the documentation for which can be found here: Documentation Matlab's design itself is based on this IEEE paper: ...
2 votes
0 answers
433 views

How do 2D DCT basis functions interact to produce 8x8 JPEG tiles?

This section is a bit of an intro. If you want to skip directly to where the problem is explicitly outlined, skip to the bottom of this post. Please note that I'm not hip with mathematical lingo, so ...
2 votes
0 answers
64 views

Is it possible to create a causal filter with a positively-sloped phase response?

I am currently prototyping a set of noise-cancelling headphones that utilize active EQ to modify the noise-cancelling signal, allowing the user to modify the frequencies that they hear or don't hear. ...
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2 votes
0 answers
60 views

Explicit formulation of the role of eigenvectors of the matrix of a linear time-invariant filter

At this point in a lecture by MIT Professor Strang the idea of gaining insight into a filter by studying its eigenvectors is introduced. The idea is clear with the example chosen in the lecture: an ...
2 votes
0 answers
173 views

How to Extrapolate a 1D Chirped Signal?

Following a past question, I'd like to extrapolate a signal like the one below: (red is signal, blue is the the extrapolated ) ...
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2 votes
0 answers
139 views

Why is channel estimation done after synchronization and why does it work?

I am interested in Software Defined Radio communications where almost all processing is pushed to the digital domain. I'm wondering why is channel estimation done after frequency and phase ...
2 votes
0 answers
66 views

How can I extract the 2 polyphase components of a signal after sampling at the half of sampling rate

Suppose I have a continuous signal $x(t)$, which was sampled using sampling function $s(t)$ whose sampling rate is $T_s$.How can I sample the continuous signal by Ts/2 instead of Ts in order to get ...
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2 votes
0 answers
176 views

What is the correct way to do Short term Fourier transform and extract the phase information from local sections of a signal?

I took a triangular voltage signal and taking it's time derivative I obtained the current through a pure capacitor. Then I took different portion of voltage and current signals, took their Fourier ...
2 votes
0 answers
515 views

How to eliminate matched filter background?

The question My goal is to detect an unknown frequency $f_1$ with a mixer and a matched filter. My simulation shows (below) that I correctly identify the 50 kHz external signal - but it also ...
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2 votes
0 answers
100 views

Distinguish between chords and single notes

I am implementing a pitch detection system where I detect pitch in single notes (guitar). I recently found this library, that detects chords in an audio signal. When there are chords in the signal, ...
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2 votes
0 answers
314 views

Constructing $X(\omega/2)$ from the FFT of $x[n]$

Let $X(\omega)$ be the Discrete Time Fourier Transform (DTFT) of $x[n]$, I want to construct $X(\omega/2)$. Precisely, I use FFT function to compute the samples of $X(\omega)$ in one period, say $[0,...
2 votes
0 answers
279 views

1/f noise generation

Recently I was reading a paper about the pink noise generation. But I don't have any background of this field. I am confused with some part in the paper. First, the Voss's algorithm generated a ...
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2 votes
0 answers
171 views

Optimal method to calculate Fractional Fourier for Chirp signals

There are several method exist in the literature to calculate fractional Fourier transform. My interest is in chirp signals and want to find time delay estimation using fractional Fourier transform (...
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2 votes
0 answers
81 views

Why does filtering the same discrete dataset while choosing different sampling rates yield different results?

If I have a two-dimensional discrete dataset (one space, one time), and I create subsets of this dataset by "sampling" (although the original dataset isn't continuous) it at different rates, should I ...
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2 votes
0 answers
52 views

Why doesn't the mel-scale use the twelth-root of 2 instead of a biased sample listener?

For the mel frequency spectrum, which is used extensively in audio-processing, the technique uses subjects to identify pitches of uniform distance from one another. Isn't this distance just the 12-th ...
2 votes
0 answers
66 views

Is there an exact solution for this re-sampling problem?

I want to know if there is an exact solution for the following problem and how to approach solving it: I have a discrete-time signal where the Nyquist theorem is satisfied: $r_k = \sum_i a_i^{(1)}h^{...
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2 votes
0 answers
1k views

Extracting the phase of a jittering sine wave using python

The background: I conducted an experiment where I rotated an object (with three-fold symmetry) many times and recorded the projection of the object. I should be able to tomographically reconstruct ...
2 votes
0 answers
354 views

DC offset removal from tetra signal

Hey I want to remove DC offset from tetra signal captured as inphase and quadrature phase samples(I and Q samples). I and and Q samples are 16 bit signed values. I tried averaging 2000 I and Q samples ...
2 votes
0 answers
380 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 ...
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2 votes
0 answers
429 views

How to model/estimate channel in discrete time with different sampling time?

I want to estimate a channel based on LTE 3GPP EVA with given power delay profile (set of average power and delay of channel taps). ...
  • 21
2 votes
0 answers
121 views

Voice sample prediction scheme

I have some telephone voice audio with occasional "blips" in the audio. The blips appear to come from an IP link buried in the PSTN (this is a conceptual explanation, so don't worry about things like ...
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