# Tag Info

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### Entropy : do we prefer higher or lower entropy?

You seem to have a number of misunderstandings, which I'll try to clarify while also trying to help with your questions. The entropy of a source $H(S)$ gives the average codeword length to encode a ...
• 15.3k
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### Educational purpose - What is the correct way to simulate a multipath fading channel which has ISI

Lets say we want to transmit a sequence of discrete data $\left\lbrace x[n] \right\rbrace$. But because we are living in analog world, the sequence must be modulated. Call $T_s$ is symbol duration ...
• 6,605
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### Why use parametric based estimation methods - confusion regarding terms

Hi: I'll try to answer as briefly as possible and only with respect to statistics. not dsp. In statistics, if you have a nice pdf such as the normal distribution, then maximizing the likelihood is ...
• 1,117
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### Doubts on LMS derivation

Here I expected $y(n)$ is to be computed by convolving $x(n)$ with $h(n)$, but in the equation given by Wikipedia it is shown as a matrix multiplication $y(n) = h^H(n).x(n)$. Are these two ...
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### Why Zero Padding in the Center of the DFT Interpolates / Upsamples the Signal (Sinc Interpolation / DFT Interpolation / Periodic Interpolation)

What you are experiencing is technically called interpolation by DFT; i.e., interpolating a time-domain sequence $x[n]$ by properly zero filling the middle portion of it's DFT $X[k]$ (and taking the ...
• 28.3k
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### Relationship between information retrieval and source separation in signal processing

There are, a few discrepancies that might be making a difference here. My suggestion would be to edit the question for clarity. There are quite a few assumptions that lead to non-straightforward ...
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### Proper method for generating Channel coefficients in MATLAB

Complex channel coefficient is just a way to represent the independent real coefficients. You just need to generate ...
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### "Don't window a transient signal"

To build on Laurent's answer, here is an example. Top frame shows an example transient signal: a damped sine wave. As the signal decays very quickly, the first 0.1s of the signal is the most ...
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Let me try to establish the relation between the univariate PDF for a real Gaussian and the univariate PDF for a complex proper (i.e. circular symmetric) Gaussian. You know that $p_x(x)=\frac{1}{\... • 6,228 4 votes ### Computer exercises and solutions in signal processing "Digital Signal Processing: A Computer-Based Approach" by Sanjit Mitra is what you need I guess, especially the exercises at the end of each chapter. There is a booklet on the Internet again by Mitra,... • 1,976 4 votes Accepted ### Unable to understand the derivation of the update equation for LMS so with an LMS filter, we have a time-variant$N$-tap FIR filter: $$y[n] = \sum\limits_{k=0}^{N-1} h_n[k] \, x[n-k]$$$x[n]$is the input signal,$y[n]$is the FIR output, and$h_n[k]$are the FIR ... 4 votes ### Finding the time domain equation corresponding to a given DFT (1) I'm not sure my intuition is right Almost, but you're missing the fact that if you're sampling at 4000kHz, the signals alias; after sampling at 4000kHz, a sine wave at 1500Hz is ... • 12.9k 4 votes Accepted ### Finding the time domain equation corresponding to a given DFT Here's the pure math: $$x[n] = \frac{1}{N} \sum_{k=0}^{N-1} X[k] e^{i \frac{2\pi}{N} nk }$$ $$x[n] = \frac{1}{8} \left[ (5.657 + i 5.657) e^{i \frac{2\pi}{8} n 3 } +(5.657 - i 5.657) e^{i \frac{2\... • 7,590 4 votes ### Recommendation for courses / studies on digital signal processing I've kind of grouped your subjects into larger overall subjects. Note that there's a lot of overlap here, with the possible exception of actually making it work in a microprocessor (except -- in my ... • 12.9k 3 votes Accepted ### Lloyd Max Quantization and Clustering : Part 1 Different. Lloyd-Max is a special type of scalar quantizer design which is optimized (in terms of MSE) to source pdf. Hence the quantizer is generally non-uniform. Lloyd's algorithm (and the more ... • 4,295 3 votes Accepted ### Help in understanding from book expression of variance of an estimator : PRBS vs real valued input A PRN sequence is a Pseudo-Random Noise sequence, often generated by using an Linear Feedback Shift Register (LFSR) with the feedback taps done by using a primitive irreducible polynomial in GF{2}, ... • 52.3k 3 votes Accepted ### Beginner level confusion regarding symbols used in modulation An M-QAM modulation contains M different constellation symbols. Hence, in one symbol you can encode \mu=\log_2(M) bits. (i.e. 6 bits for 64-QAM for example). Now, the bits are equally distributed ... • 6,228 3 votes ### LTI systems inverse of each other You may also look at the transfer function (s-domain) of the two systems:$$H_1(s)=\frac{1}{2}e^{-s}H_2(s)=2e^{s}$$And the two systems in series will result in$$H_1(s)H_2(s)=1$$which means ... • 4,295 3 votes ### What are your tips for DSP self-study? DSP would be a quite broad subject and where to start would depend on your ability to pick up information, learn, understand and implement it. A basic course for supplying us with the basics to ... • 79 3 votes ### What Resources Are Recommended for an Introduction to Signal Processing (DSP)? I would add to the list the book "Digital Filters", by Richard Hamming. A short classic, rather than a heavy tome. 3 votes Accepted ### Why do digital modulation when the signal entering the channel is analog? I think part of your confusion is actually between discrete-time and digital signals. Some textbooks do not clearly distinguish between them. All signals that exist in the physical world are real. So,... • 15.3k 3 votes Accepted ### Is there a rule of thumb for selecting the variance of the input? You can define your model as$$\hat{x}[n] = \frac{1}{||\mathbf{x}_{n}||}\mathbf{A}^T\mathbf{x}_{n} +\frac{1}{\sqrt{\mathsf{SNR}}} w[n]$$In this way, you define a range for$\mathsf{SNR}$in dB (e.g. ... • 4,295 3 votes ### Digital Signal Processing DSP Overview study documents There are some books (some free) that cover most DSP topics with a claim of easy approach, probably they cover the most important fundamentals: 1- Understanding Digital Signal Processing_R.Lyons 2- ... • 28.3k 3 votes Accepted ### How is the number of amplitude levels decided in modulation techniques? There are$M$symbols in an$M$-QAM constellation where two carriers I and Q are amplitude modulated, and there are$N=\sqrt M$amplitudes for each I and Q carriers (for$M\ge4$). In$16$-QAM there ... • 4,295 3 votes Accepted ### Doubts and some confusion on variance for complex rv If the imaginary and real components each has a variance of 0.5, then what would be the total variance? The variance of the complex RV in that case would be$0.5 + 0.5 = 1\$. If on the other hand, ...
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Q1: Dependence of estimation performance on number of data points Since LMS and RLS are adaptive filters, their estimation performance improves as the number of their iterations increase. Hence more ...
• 28.3k
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### which filters are these?

When only a rough pole-zero plot (without exact locations of them) is given for a filter, then the only procedure that remains to evaluate the frequency response magnitude will rely on the geometrical ...
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