All Questions

0
votes
1answer
52 views

Extremely low frequency filters

I have a data acquisition board(A/D+Digital Signal Processor) and I want to check if a digital high-pass filter(implemented in DSP) at an extremely low cut-off frequency(0.05Hz) is actually working. ...
0
votes
0answers
21 views

Why do we need two Long training sequences for Channel Estimation in 802.11a and 802.11p systems?

I am working on 802.11p and was wondering about the channel estimation part. At physical layer (PPDU), The preamble contains 10 Short Training Sequence and two Long training same sequences. Why do ...
0
votes
0answers
20 views

PSD Periodogram smaller segments compared to larger segment

I am calculating the power spectrum of a heart rate variability via FFT and a Welch window. I have a sample of 500 points as the input signal. The signal was broken up into two 128 point segments. ...
0
votes
0answers
18 views

Space-time filtering vs. beamforming

Say I have a dense linear array of sensors in space and an acoustic signal propagating through them. In this case, how would delay-and-sum beamforming compare to space-time filtering by masking the ...
0
votes
1answer
32 views

Homography for (small baselien) Stereo Image Registration

If the distance between two stereo cameras (baseline) is much smaller than the distance to the geometry, is it possible to align the resulting two stereo images using a homography?
0
votes
1answer
22 views

real time signal analysis of output from an audio device

I'm writing a test program that can detect pops/cracks/noise (unknown frequencies and duration) in the audio output of an audio device. The purpose of this program is to reduce human error and make ...
0
votes
0answers
37 views

CDMA-DSSS with orthogonal codes and BPSK modulation: proper way to demodulate

I am having problems when demodulating the signal: If I demodulate the sequence chip by chip and then operate only with binary information the "integrate and dump" (correlator) sometimes will provide ...
0
votes
0answers
11 views

Signal delay in phase interferometry?

I want to write program for phase interferometry to understand how its work. For the beginning I generate signal, which arrives on two antennas with delay. Matlab code: ...
0
votes
2answers
67 views

Differential Equations applications in Signal Processing [closed]

Does differential and partial differential equations subject has applications in Signal Processing? I have basic DSP background and know Matrix algebra and Fourier transforms very well, but I am not ...
3
votes
1answer
69 views

Why is this recursive DFT algorithm not equivalent to this iterative method?

Edit 1/30 - Taking @Fat32's edits into account, it seems like there is still an issue with the scale of the frequency axis. While version 2 correctly identifies the response at 1 HZ, version 1 seems ...
0
votes
0answers
21 views

Convolution in the Hartley Domain

The convolution Theorem of the Hartley Transform is given by $$ Y_{Ha}(k) = X_{Ha}(k)H_{Ha}^{e}(k) + X_{Ha}(-k)H_{Ha}^{o}(k) $$ where, $$ H_{Ha}^{e}(k) = \frac{H_{Ha}(k) + H_{Ha}(-k)}{2} $$ $$ H_{...
1
vote
1answer
17 views

Feature normalization (scaling) for Hyperspectral images

have been straggling with the concept of feature normalization for the hyperspectral images. Respect to my problem I have attached a picture of my problem which clearly stands the issue which I have.
0
votes
1answer
32 views

How to calculate an All-Pass filter quantization coefficients

Given $$H(z) = \frac{z^{-1}-0.8}{1-0.8z^{-1}}\text,$$ does the filter stay an All-Pass filter after quantization of coefficients? If so, how can I prove it mathematically?
0
votes
0answers
34 views

Transfer function estimation of a noisy system

Overall description I am trying to estimate a filtering system’s transfer function, given its input and output. This system takes $x$ as input . This signal is low pass filtered and added to a WGN by ...
0
votes
2answers
39 views

Cannot figure out the convolution operation in this problem

A linear system S has the relationship $y[n]=\sum_k {x[k]*g[n-2k]}$, k ranging from $-\infty$ to $\infty$, between its input $x[n]$ and output $y[n]$, $g[n]=u[n]-u[n-4]$. Determine $y[n]$ when $x[n]=...
0
votes
0answers
9 views

Correct way to calibrate RX into a measuring receiver

While playing with my SDR (Software Defined Radio) Board, I was interested in performing a TX output power table at different center frequencies and TX antenna gains. I have an RF frequency generator....
0
votes
1answer
24 views

What is fft input size for ofdm?

From the Transmitter comes a block of size N+L (where N is the number of subcarriers and L is the cyclic prefix length). Then the block goes through a Channel which adds delay and AWGN, so this ...
4
votes
2answers
107 views

Is the Sobel filter a high pass filter, and if not, what is the difference between them?

I am an artist with an interest in signal processing. I realize that maybe this question very basic, but the web banner on the frontpage says "anyone can ask", so I assume that means beginners too. ...
-1
votes
3answers
37 views

How does real-time signal processing work when the signal we deal with is assumed to be known for all times?

One thing that never sat right with me after my signal processing course is that in order to do signal processing, we must know the entire signal $x(t)$. For instance, I cannot take the Fourier or Z ...
1
vote
1answer
34 views

DFT zero-padding of signals starting before n=0

If a signal starts before n=0, what part of the signal should be used to compute DFT after zero-padding? For example, x(n) = {1, 2, 3, 4, 5}, where x(-2) = 1 and x(0) = 3. If this signal is zero-...
0
votes
0answers
31 views

Accelerometer signal processing

I'm new signal processing (this is my first pratical application), so I ask sorry if my question is simple. My challenge is to see the displacement of accelerometer when I have vibration too. I do ...
-1
votes
1answer
25 views

average linear phase (group delay)- how can be calculated, given a signal samples at frequency F?

Average linear phase (group delay)- how can be calculated, given a signal samples at frequency F? The definition doesn't help since the frequency is constant: $-[signalPhase(n)-signalPhase(n-1)]/[...
1
vote
1answer
41 views

time downsampling vs. frequency downsampling [closed]

$x[n]_M$ is a finite length sequence of length M. if: $$ y = x[nN]_M \tag{1} $$ is called downsampling in the time-domain. then what do you call the process of converting going from a M-point ...
0
votes
0answers
23 views

Power Spectral Density of discrete White Gaussian Noise defined with variance and sampling interval

From Creighton and Anderson Chapter 7 on Gravitational Wave data analysis: Please explain where the delta t and the limit came from in this derivation.
0
votes
1answer
18 views

Square of the ratio of errors in power quantities in decibels

A ratio of amplitude quantities $A$ and $B$ can be expressed in decibels as: $$20 \log_{10}\left(\frac{A}{B}\right) \text{ dB}.$$ A ratio of power quantities $A^2$ and $B^2$ can be expressed in ...
-1
votes
0answers
28 views

Correlation between two signals in time domain

I have two signals, which correspond to the same physical event (acceleration signals) measured from two different sensors. What would be the equivalent of a correlation (ranging from 0-1). I would ...
0
votes
0answers
18 views

Reducing noise on several Transfer Function measurements

INTRODUCTION I want to obtain the transfer function of certain system (a ground "path", in this case) using an impact hammer for the excitation and one accelerometer (measuring vertical direction ...
0
votes
1answer
45 views

Does dividing the magnitude spectrum of white noise by sqrt(2) give an RMS magnitude spectrum?

I understand that the RMS Amplitude of a sinusoidal signal is around 0.707 ($\frac1{\sqrt2}$) times the Peak Value, but this is not true for noise. However, an FFT of a noise signal indicates ...
0
votes
0answers
13 views

Scipy Welch's gives different first element

I've re-implemented Welch's method and want to compare it to scipy.signal.welch. However, the first two and last elements of the resulting array are different. My ...
0
votes
2answers
43 views

Why Coherence is not a valid metric when performing impact excitation?

INTRODUCTION I have understood that Coherence is a function that explains the linear relationship between an excitation signal and a response signal. I know how it is calculated and why it is bounded ...
0
votes
0answers
13 views

Bundle adjustment optimization parameters

While reading the Wikipedia article on Bundle adjustment, I came across the following objective function used to represent the bundle adjustment problem. I have two questions regarding this objective ...
-1
votes
1answer
39 views

Estimation filter [closed]

Can anybody explain me the basic difference between kalman filter and particle filter? For the process of estimation which is the best filter to be ised among them and why? Please provide some example ...
0
votes
1answer
15 views

Z-transform of not quite an upsampler

I know the z-transform of an upsampler is: $$ y[n] = \begin{cases} x(n/L) &n=0,\pm L, \pm 2L, ...\\ 0&otherwise \end{cases} \longrightarrow Y(z)= X(z^{L}) $$ if $x[n]_L$ is defined to zero ...
-1
votes
1answer
33 views

How to keep low frequencies in DCT

How can I keep a percentage r of the low frequencies of a Nx1 signal x using the Discrete Cosine Transform of it? Is it simply zeroing all but the first rN elements of DCT(x)?
1
vote
1answer
41 views

How do I find the transfer function in the frequency domain?

I was doing some exercises with transfer functions, they were always under the form of $H(z)$ and $H(e^{jw})$ for the frequency response. Today I have found one with $H(f)$. I would like to ask if my ...
1
vote
0answers
29 views

Generate time domain signal from frequency domain filter

I am familiar with using the Fourier transform to take a signal from the time domain to the frequency domain. What I would like to do is the reverse: describe a signal in the frequency domain and then ...
1
vote
1answer
31 views

DFT product of sinusoids

(From Shaums DSP outline, 2nd edition, page 248, problem 6.21) Book says, evaluate the Sum: $$ S = \sum^{N-1}_{n=0} \Bigg( x_1[n] \ x^{*}_2[n] \Bigg) $$ when: $$ \begin{aligned} x_1[n] = \cos\left(...
0
votes
0answers
22 views

Applying a filter on an input sequence in matlab

Given a input sequence $x = {x_1, ... x_n}$ and a filter with l elements $h = [h_1, ..., h_l]$ with l < n. We want to filter the input sequence with the specified filter. My first thought was to ...
0
votes
0answers
16 views

Filter a picture by its color spectrum

I want to split an image in half and remove all colors from one half which aren't present in the other half. I already converted the image from RGB to YCBCR but I'm not sure (from a theoretical ...
0
votes
0answers
26 views

16-QAM output waveforms vs. 4-PAM levels

I've found some conflicting information about how the I/Q waveforms look compared to the 4-PAM signals before the modulator. Here it is shown that the 4-PAM digital signals are filtered, so the ...
0
votes
1answer
33 views

How do Anti-Aliasing-Filters in audio signal processing work?

I am a little confused about the use of anti-aliasing filters. As on how I am confused, please consider the following task: Consider a simple sampling rate conversion system with a conversion rate ...
0
votes
2answers
28 views

What is Causing a Noise Signal in USB Audio Recording?

I am experiencing the following peculiar noise signal when recording from my Behringer Xenyx Control 2 over USB. There is frequency at around 2293 hz as show: And over time, it produces the ...
4
votes
4answers
241 views

Estimators for improved spectral subtraction of noise

Real zero-mean Gaussian white noise, independent of a clean signal $x$ and of known variance is added to $x$ producing a noisy signal $y.$ Discrete Fourier transform (DFT) $Y$ of the noisy signal is ...
1
vote
0answers
53 views

Residual carrier tracking with PLL

Residual carrier systems such as PCM/PM/NRZ and PCM/PM/Bi-phase are common in space applications. Compared to suppressed-carrier systems such as BPSK, the literature sources on residual-carrier ...
0
votes
0answers
33 views

Linear difference equation and method of Least Squares

I'm reading the book "Fault-Diagnosis Systems" by Isermann in the par. 9.2.1a. The author explains how to estimate the parameter of a linear difference equation using Least Squares. We start with a ...
0
votes
1answer
14 views

how is this method of proving shift invariance correct

I got this answer from here. But i don't know how this method is correct. Until now to prove shift invariance what i did was : step 1: delay output and write it in terms of input. step 2: delay input ...
1
vote
2answers
40 views

What is the duration of the spreading sequence

I have a question regarding the spreading sequence duration using Walsh matrix. I've read a paper related to that, they consider the signal $S = R(S) + I(S)$, where $R(S), I(S)$ are the real and ...
0
votes
2answers
45 views

How to find the instantanous SNR over Fading channel

I would like to prove that the instantnous SNR of flat fading channel $$y=hx+n$$ is $$\gamma=\frac{|h|^2}{N_0}P$$ where $E\{z\}$ is the expectation of $z$ and $$ E\{x\}=P $$ $$ E\{n\}=0 $$ $$ E\{...
0
votes
0answers
7 views

Random sampling Bartlett spectrum estimation vs Welch

I'm trying to estimate the spectrum of a noisy time series and considering two approaches and their relative correctness. Let's say the time series is 800s long. Option 1 is to do a Welch spectrum ...
1
vote
1answer
44 views

downsampling DFT with aliasing

(Schuam's DSP Outline, 2nd edition, problem 6.11(c), page 241). Is there a DFT down-sampling property that looks something like this: Given $x[\![n]\!]_M$ we want to downsample from M to N to obtain ...

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