All Questions
27,703
questions
0
votes
1
answer
115
views
Filter to speed up convergence of geometric series
I want to speed up convergence of geometric series
$\ \ lim + c^n \ \ $ where $|c| < 1$ and $lim$ is not known.
A basic low-pass filter, here Butterworth, is good for $-1 < c < 0$ but not $0 ...
- 608
0
votes
0
answers
2k
views
Why Normalized Cross Correlation Score of different templates is high?
I am using OpenCv's built in template matching function to search for an object in image. I am using Normalized Cross Correlation Method.The function is returning a value which I think indication of ...
4
votes
1
answer
4k
views
Is it possible to design noncausal filters in Matlab?
I'm trying to design a lowpass IIR filter with 5Hz cutoff frequency (sample frequency is 200Hz). i know how to create it with fdatool, or with functions such as 'butter' or 'ellip'. However, i think ...
- 41
3
votes
2
answers
952
views
When calculating the Nyquist frequency should carrier frequency be included
This isn't my field, so please forgive any misnomers on my part.
I'm looking into buying a amateur radio receiver, and I'm thinking about what sampling rate I need. I'm most interested in satellite ...
- 131
0
votes
0
answers
278
views
BandPass and StopBand FIR filters (Hamming) is not working
I have two groups of 3 frequencies of tone (music),
First Group
Tones: 39 (77.7817 Hz), 40 (82.4069 Hz) and 41 (87.3070 Hz).
Second Group
...
- 123
0
votes
1
answer
146
views
Pesq numbers and clean speech comparison to processed speech
I am trying to evaluate my processed speech for my DSP project. My project is an implementation of an MMSE algorithm proposed by Y.Ephraim and D. Malah, "Speech Enhancement Using a Minimum Mean Square ...
- 57
3
votes
2
answers
2k
views
Are Convolution and Deconvolution Kernels the Same?
I need to clarify this and rather confused by this.
Lets say:
$x = h * g$
$x$ - measured data
$h$ - raw data
$g$ - instrument response function (convolution kernel)
So lets say I ...
- 33
2
votes
1
answer
1k
views
Can I take piecewise FFT of a larger input sample?
I have a N point sequence x. Let X be the fft(x). (Assume x is arbitrary)
where,
x=[x1 x2 x3 x4 x5 x6 x7 x8]
fft(x)=[X1 X2 X3 X4 X5 X6 X7 X8]
How do I get the ...
- 63
2
votes
1
answer
4k
views
Why oversample data before using raised cosine filter?
In the process of creating a baseband signal, the complex symbols are filtered using a raised cosine filter to perform pulse shaping (I'm following some literature as a guide). The pulse shaping is ...
- 55
7
votes
1
answer
390
views
Analytical Expression for Convolution of Two 2D DFTs
I am trying to do an image analysis problem on some images, and I want to calculate some things in the frequency domain which are giving me problems. Say I have an (discrete) image $I(x,y)$ of size $...
- 171
3
votes
2
answers
150
views
How to find the output signal of a filter using state space matrices?
I have a filter.
It has two poles and two zeros.
I found the state space equations and the matrices A, B, C, and D
Now. I have 9 samples that I need to process with my filter.
How do I use A,B,C,D ...
- 233
1
vote
2
answers
3k
views
Calculating Savitsky-Golay filter coefficients - normalization
Using the matrix equations found on Wikipedia I wrote some Python code to compute the Savitsky-Golay coefficients for $m$ data-points, using a polynomial of degree $k$. Here it is:
...
- 11
1
vote
1
answer
1k
views
Sub pixel shift causes weird results
I am trying to shift an image on a subpixel level, with the method described here:
http://www.mathworks.com/matlabcentral/fileexchange/18401-efficient-subpixel-image-registration-by-cross-correlation/...
- 111
3
votes
4
answers
8k
views
FIR filter design with frequency sampling method - setting proper phase response for IDFT
I'd like to implement freuqency sampling method for linear phase FIR filter design using IDFT transform.
My procedure goes like this :
determine desired magnitude response value in frequency points
...
- 151
0
votes
1
answer
176
views
Phase Estimation in speech enhancement
I am reading a recent paper titled "Phase Estimation of Speech Enhancement - unimportant, important, or impossible?" by Grekmann et al. published in the 2012 the IEEE convention. The paper proposes an ...
- 57
0
votes
0
answers
328
views
Choosing the frequency for a comb filter
I have an audio sample. From doing FFT on it it looks as if I need to use a comb filter to remove resonant frequencies. This is what I generate:
I honestly have no clue where to start unfortunately.
1
vote
1
answer
90
views
Frequency of a noisy signal with fixed width pulses
My electricity meter has a front panel LED which pulses in proportional to the current energy rate. The frequency changes but the pulse width is set at 250ms. Due to environmental conditions there's ...
- 13
0
votes
1
answer
416
views
Why does FFT generate a jaggedy signal
I have an application that fills a buffer from my computer's microphone and does an FFT. My objective is to figure out what frequencies are in the sample.
I've tested the application by whistling as ...
- 103
12
votes
1
answer
24k
views
Converting raw I/Q to dB
I am getting I/Q data from a software-defined radio. I want to do some stuff on signals in the data, but only if it exceeds a certain range. What is the general procedure to get dB (dBm, or anything)...
0
votes
0
answers
215
views
Adaptive Line noise removal using IIR notch filters
I'm trying to filter out line noise(60Hz and 120Hz) from a EEG signals received over a bluetooth link. I'm proposing to use a IIR notch filter to filter out the line-noise which varies w.r.t to ...
- 418
3
votes
2
answers
2k
views
Effects of DC offset on a signal
What are some of the reasons why DC offset is considered undesirable for a timeseries signal other than wastage of power during transmission ? Specifically, How does it cause spectral leakage and out ...
- 418
3
votes
2
answers
3k
views
convolution matrix for image scaling
Is there any way how to compute convolution matrix for Nearest Neighbor (bicubic, bilinear) image scaling (upscale/downscale)?
- 31
1
vote
1
answer
1k
views
The Nyquist-Theorm behind the fft
I saw a code in Python in the scipy.org (http://docs.scipy.org/doc/scipy-dev/reference/tutorial/fftpack.html) and found this:
First question: Is it right that T = 1/800 <==> fs = 800 Hz fulfill ...
- 11
1
vote
1
answer
1k
views
Need help to understanding concept of particle filter
I get confuse with the basic theory of particle filter for tracking single object..
What I want to ask is:
In some paper, they explained about velocity in state vector.. Are we
randomly put number ...
- 35
0
votes
1
answer
153
views
Quadrature subsampling result not as expected
Let's suppose I have an ADC running at 81.824MHz. I am quadrature subsampling a signal that is at 143.5MHz using a sampling rate of 81.824MHz/4 = 20.456MHz = Fs. I expect the signal to appear at ...
- 103
0
votes
1
answer
1k
views
Shape recognition, hough transform
I'm trying to match a picture saying "this is ducks, this is towers" by giving votes from the hough transform of a picture.
I've found this article http://ttic.uchicago.edu/~smaji/papers/hough-...
3
votes
1
answer
3k
views
Implementing overlap add method for convolution with a slice of the filter
In overlap add method for convolution a filter $x$ of length $M$ will get convolved with a signal $y$ of length $N$ where $M << N$, i.e., $z = x * y $.
Here the signal $y$ is sliced into ...
- 654
2
votes
2
answers
4k
views
'A priori' and 'a posteriori' SNR
I am reading this paper about speech enhancement using a minimum mean square error short time spectral amplitude estimator for our speech enhancement project. Basically in the paper they mix a clean ...
- 151
2
votes
3
answers
7k
views
how to make CIC compensation filter
I gotta wrap my head around to design CIC compensation filter
I'm studying by referring these materials:
Altera, "Understanding CIC compensation filters
Hardware Efficient FIR Compensation Filter
...
- 21
2
votes
1
answer
135
views
Implications of $X( -j\omega ) = X^*(j\omega)$
What are the implications of:
If $x(t)$ is real and $x(-t) = x^*(t)$, then $X(-j\omega) = X^*(j\omega)$ and $X(j\omega)$ is real.
I am trying to understand it and I would like to research it ...
- 357
0
votes
1
answer
892
views
Get data ready for IFFT
I am having troubles applying the IFFT function to some data I have. I already had a look here Complex conjugate and IFFT and here What assumptions should be used to invert spectrum into time domain ...
- 413
5
votes
1
answer
9k
views
Mel filter in MFCC - is it necessary?
Is it necessary to use filter bank in MFCC process? Can anyone explain what is the Mel filter? I know that frequency in hertz is converted into Mel scale but is this formula can be directly applied ...
- 69
0
votes
1
answer
309
views
Changing the cutoff of an IIR lowpass filter with minimal transients?
I have a 1st order lowpass IIR filter of the form
$ H(z) = \frac{b_{0} +b_{1} z^{-1}}{1+a_{1} z^{-1}} $
implemented using the direct method my code looks something like this
...
20
votes
1
answer
14k
views
Cepstral Mean Normalization
Can anyone please explain about Cepstral Mean Normalization, how the equivalence property of convolution affect this? Is it must to do CMN in MFCC Based Speaker Recognition? Why the property of ...
- 215
0
votes
1
answer
165
views
Evaluation of incremental sensor
Evaluating a volume flow incremental sensor does not deliver expected results.
The pump of which the volume flow is to be measured has a hand-calculated flow rate of
$$Q = \dfrac{n}{ 60 \;\mathrm{s/...
- 121
-1
votes
1
answer
201
views
Fourier series qn determine the fourier series coefficients
Can someone please help me with this Fourier series question:
Determine the Fourier series coefficients of $x(t)$ given as $x(t) =
> \cos4t +\sin8t+3$?
- 11
3
votes
1
answer
2k
views
For a standard second order transfer function, what is the equivalent time domain significance of $\zeta>0.707$?
In frequency domain $\zeta>0.707$ implies no resonant peak in frequency response. But I am unable to correlate what is the exact time domain effect of this? If $\zeta=0.707$ acts like an '...
0
votes
1
answer
71
views
Weak sense stationarity sufficient for multitaper spectrum analysis?
This is a general question on multitaper spectral analysis of signals and stationarity
I work with time series which are non stationary. In this regard I have two questions
Is weak sense ...
- 333
4
votes
2
answers
5k
views
Why optical flow ? why not tracking
I have a question that might be stupide !
Supposing that I try to detect object moving in a video or human action.
Many works are based on optical flow computation.
My question is why using OF is ...
0
votes
1
answer
220
views
coded filter vs fdatool : inconsistency in the results for same parameters
I tried creating a filter in 2 different ways in Matlab and I obtain different results: one filter is stable, whereas the other one is unstable.
Coded filter
...
- 413
1
vote
1
answer
215
views
Filters performance analysis
I am working on some experimental data which, at some point, need to be time-integrated and then high-pass filtered (to remove low frequency disturbancies introduced by integration and unwanted DC ...
- 413
0
votes
0
answers
102
views
How to simulate two OFDM Users with low complexity FFT/IFFT?
have two User one of them sending over freq (0-B] and the other transmit over (B-2B]. Both of them are using OFDM and each one has Nc subcarriers. I wanted to simulate the received signal using Matlab....
- 1
1
vote
1
answer
543
views
DCT step in MFCC process
During MFCC process FFT is done to get the power spectrum but last step is DCT in order to get back to time domain. Cannot DCT be used in the first case to convert the signal to frequency domain?
- 215
2
votes
2
answers
2k
views
Questions about Active Noise Cancellation
Being new to ANC, this is my understanding of how ANC works:
Ambient noise (n) is entering a geographically small zone. To suppress the noise, an interfering (corrective) sound is injected ...
- 329
0
votes
1
answer
91
views
Expected value of coupled signals is zero
Suppose there are two vector signals, $u$ and $v$, which are functions of time. Given, $E[uv^T]=0$, what is the physical significance of this statement. For clarity, assume $u$ and $v$ are noises in a ...
- 113
3
votes
1
answer
245
views
Non Equispaced / Non Uniform DFT Bandwidth
I need to construct Fourier transform of non-equispaced data.
That is, I have signal $s(t)$, $t\in[0,T]$ sampled at non-equispaced points $t_k$, $k=0...N-1$ with sample values $s_k = s(t_k)$. For ...
- 41
2
votes
3
answers
1k
views
What is the difference between general microprocessors, DSP and FFT chips?
I know that a general purpose microprocessor requires 18 operations to perform each butterfly of the FFT, but I do not understand how does using using a DSP or FFT chip improve FFT processing?
Any ...
- 233
0
votes
2
answers
653
views
up down sampling and low-pass filters
I am trying to figure out what seems very trivial thing about down sampling and up sampling. The problem that I am facing is how to find the effects of up sample on a signal followed by a filter and/...
- 57
2
votes
1
answer
9k
views
Additive but not homogeneous continuous system?
I am trying to find an example of a continuous system that is homogeneous, but not additive.
So far, the only example I could find was an example from this page, which describes system as $y(t) = \...
- 123
5
votes
4
answers
3k
views
Extending 1D window functions to 3D (or higher)
(cross post of SO: https://stackoverflow.com/questions/27345861/extending-1d-function-across-3-dimensions-for-data-windowing )
For the sake of image (volume) registration, I'd like to apply a ...
- 153