# All Questions

23 views

### Amplifying part of a signal

If I want to amplify a certain frequency in a digital signal, can I just take the FFT, increase the real part of the value for the frequency I want (leaving the imaginary part alone), and then take ...
14 views

### Using Goertzel Algorithm in under-sampling

I plan to calculate a signal's phase using Goertzel Algorithm. I have 2 signals coming to microcontroller's ADC. Need to measure the phase difference between them. Signals are 15MHz sinusoids. Sample ...
23 views

### Filtering a Morse code (CW, OOK) signal

I am building a morse code decoder in Python. I am using SciPy and Numpy for FFT, filter, etc. It is coming along ok, but the signal is noisy. I am extracting the dominant frequency from the FFT of ...
17 views

### Introduction to Clustering and Classification of Linear Sequence

I'm a programmer/engineer that is getting into developing prototype wearable technology. I would like to be in a position to interpret raw accelerometer data and categorised the data into activities ...
15 views

### Gettiing a rectangular waveform from OOK in Python

I have a wave (wav) sound file with on-off keying. I can read the signal value at any point in time (granularity of the sample rate) from an array. I want to create another array, the same size as ...
92 views

### Why is the Canny edge detection used instead of Sobel/ Prewitt edge detection before Hough transformation?

I know that for the Hough Transform to work on an image, it needs to be a binary image. To convert from a grayscale image, an edge detection algorithm should be employed. I notice that people always ...
48 views

### How to compute the main lobe width of generalized Hamming windows (i.e. Hann, Hamming, etc.)?

Is there a way to compute the main lobe width of windows of the generalized Hamming window family (i.e. Hann, Hamming, etc.)? By main lobe I mean the first zeros left and right of the center of the ...
25 views

### What is Z plane and what does one mean by frequency and time domain [on hold]

I have read signal basics and done some problems. But while studying Z - Transform - I completely cannot understand what is z-plane / s-plane? What is the meaning of representing signal in frequency ...
15 views

### DSP review: key difference between dsPIC and SHARC or similar DSP (AD/TI) [on hold]

I'm reviewing the DSP technology, I'm familiar with dsPIC33 and FFT operation. Can anyone come across article or paper that make critical comparison between various DSP device (most recent market) ...
25 views

### How to choose the number of codewords in bag of words model

In the bag of words model, generally is it better to have more codewords or less? For example, if I have 1000 x 20 raw features, then what would be good value for codebooks? I am thinking of smaller ...
20 views

### Timing synchronization in limited channel

I need measure timing of an signal that is send through a noise band limited channel (wireless). By measure timing, I mean measure as exactly as possible when the signal has arrived at the receiver. ...
18 views

### Find Chessboard Corners using RANSAC in Matlab

I have a question: I want to implement an algorithm to find chessboardcorners out of set of given points. I have an image where I already have all the chessboardcorners there are, but also some ...
20 views

### High triangulation error

I have implemented a 2D->3D point triangulation method, which uses 2 poses P1 and P2 and 2 points back-projected to z=1 point1 and point2 to recover depth: ...
46 views

### C/C++ library for digital modulation

Is there a library written in C/C++ that offers functions like QPSK modulation?
21 views

### Convolution: 2D kernel to full matrix

We know that a convolution can be replaced by a multiplication with a toeplitz circulant matrix. Meaning, assume I have convolution kernel $h$ and matrix $I$ (of size $m \times m$ for example), then ...
39 views

### L0 norm minimization in compressive sensing

I have recently taken up studying compressive sensing related papers. Some things are not very clear to me or may be i am not able to visualize the scenario as is said. Like how L0 norm minimization ...
26 views

### Ads detection using MFCC and DTW

I am doing a project to detect Advertisements from transmission by using clipped segment (slogan) of an advertisement, based on looking at the audio track as follows: Audio Signal $\rightarrow$ ...
53 views

### What's the underlying algorithm for detail-preserving upsampling in Photoshop CC?

The detail-preserving upsampling algorithm in Photoshop CC is truly amazing. It can upscale any image while preserving details in almost real-time. And I truly wonder how it is implemented. I've ...
34 views

### use of complex conjugate of weight vectors in beamforming literature

in beamforming literature, people generally quote the following as a starting point: $y(k) = \sum_{i} w_i^*\cdot x_i(k)$ Here: i varies from 1 to N where N is the number of sensors $w_i^*$ is the ...
29 views

Suppose I want to encrypt the voice data before sending using a ham radio, for example this unit. Assume the encryption is simply AES encryption/decryption using predefined fixed key. I am thinking ...
32 views

### How to calculate local maxima of a non stationary signal using the wavelets [on hold]

How to calculate local maxima of a non stationary signal using the wavelets ?a Matlab code please , i am just lost between using the PSD or the original signal !
12 views

### State of the art post processing techniques for segmented images

I've been working on grabcut-based approaches to human segmentation in images. I've combined colour, motion and face detection cues to provide some seeds and perform a grabcut. While the results have ...
66 views

### Created Matlab echo signal: Is it an actual “echo?” Or am I just manipulating the signal to make it seem like an echo?

This is just an outline of what I did (assume that all my dimensions fit): ...
39 views

### Separating audio and video from a single video+audio file [on hold]

I have a single video file that combines audio + video. How can I separate it into two different files: the first is the audio and the second is the video ? If it can be done client side it's awesome ...
54 views

### Any way to compensate for fractional delay filter's weakness between taps?

A little background: I have an FPGA (running at 200MHz) that I am creating multipath events using buffers, all of that works. I take RF, mix down to IF, sample, make adjustments, out the DAC, and ...
38 views

### image 2-d real cepstrum with DFT ? ifftshift needed?

this is my testing image,it is taken from this paper: I tried to transform it into its real cepstrum domain with this simple matlab code: cepstrum_img=ifft2(log(1+abs(fft2(img(:,:,1))))); ...
33 views

### Intertial navigation on android phone with Kalman filter

Ok, so suppose I've got a phone with gyroscope, compass and 3-d accelerometer. I wanted to track position of the moving phone for about 1 minute with let's say 50 mm accuracy. Actually let's say that ...
16 views

### Visual regression test - Extract elements of GUI-Screenshot - MSER OpenCV

For a visual regression test I need to compare screenshots of webpages (different release-versions). I started with pixel by pixel compare. Actually I split the screenshot in different parts (maybe ...
22 views

### Definition of MFCC

I am a beginer of studying about MFCCs. I understand nearly the procedure of MFCCs like signal - FFT - melfilterbank - log(||^2) - DCT But I can't get it well about the meaning about MFCCs. I mean ...
30 views

### Sample vs. sample values

Is there any difference between the terms sample and sample value in DSP? In statistics, those are very different concepts: a sample is a subset of a population: it is a set of random variables. A ...
76 views

### Draw outline of a text in an image

I need to draw an outline of text in an image. Consider the below image as an example. Can anyone suggest me a direction to achieve this? I don't have experience in image processing. Any tools/lib ...
33 views

### Low-pass vs median filter delay

I need to design a filter to reduce noise from accelerometer readings and use this data to a control system. One of the problems of a simple low-pass filter (like a single pole IIR filter) is the ...
18 views

### how to down convert an LFM signal in a simple way? [closed]

I'm learning about LFM signals. How do i down convert LFM in simple way and display on MatLab.
11 views

### how to visualize image segmentation using matlab

After clustering in image, I want to visualize the result. To do so, I first reshape an RGB image to 3*size. The result of BSMC is the set of indices after clustering. So I change the value at the ...
35 views

### Camera Calibration using Single Input Image

Given a camera, permanently located at the same position, angle and distance from what is being captured, and a single calibration image ( a row of vertical lines [ | | | | ] ), how would one go about ...
32 views

### What is purpose of correlation kernel? IIs it high pass filter or low pass filter?

I am research about correlation kernel and I have some questions that need your help. Let see the pp. 3302-3303 in the paper: Changyang Li, et al., Robust Model for Segmenting Images With/Without ...
57 views

### Problem calculating the average power of a vector?

I am calculating the average power of a vector. I would like to compare the final expression with the simulation. However, they are not equal. Please help me to point out which steps are wrong. Thank ...
36 views

### Find and track deformable curve in noisy images

I need to find and track the location of the bottom of multiple deformable curves within a sequence of images. The images are taken roughly 5 seconds apart and there can be considerable deformation in ...
15 views

### object detection in image in matlab

I have two images ; 1. Penstand with pens. 2. Penstand with no pen is there. Now my issue is, there is any code in matlab to know: There is no pen in Penstand OR There are pens in the Penstand. ...
16 views

### Affine Parameter Optimization using simulated annealing

I am working on a project to compare images in the database. I use color and gradient orientation as features of the image and these features are not rotation invariance, therefore to compare well I ...
44 views

### Sinusoid with increasing frequency

How would you describe this signal? It's like a sinusoid but as if its frequency was constantly increasing: could you write down a mathematical description? Thanks. And no, this is not homework...
39 views

### Train a Cascade Object Detector in MATLAB

I am trying to train a cascade object detector in MATLAB using the built in functionality from the Computer Vision Toolbox. I’ve taken 500 photo’s of the sole of my shoe. Every photo is taken from ...
29 views

### MFCC extraction for speaker verification

Regarding extraction of MFCC from speech signal... I have checked for the detailed procedure of extraction of MFCC from ...
19 views

### most unitary transforms have a tendency

I read in a book that "most unitary transforms have a tendency to pack a large fraction of the average energy of the image into a relatively fewer components of the transform." My question is about ...
56 views

### The Standard Deviation of The Derivative of a Signal

Given a signal with zero mean and a standard deviation of 0.1 sampled at 5000 Hz. What would be the Standard Deviation of its 1st, 2nd and 'n' derivative? For instance, let's say we measure the ...
9 views

### MACE filters for face recognition

I am trying to implement this paper in Matlab: http://scourge.fr/mathdesc/documents/facerecog/mace.pdf Although I have followed all the steps in the paper, I am not getting any peak values as in the ...
222 views

### What does it mean exactly when two parts of a signal are correlated?

I stumble quite often upon the notion that two or more parts of a signal are correlated to describe semi-formally that they belong together. For example in image processing, two pixels on an edge ...
84 views

### Extraction of fundamental signal information-Fourier full cycle algorithm

After filtering my noisy input signal using an anti-aliasing and FIR filter, I now wish to get the basic signal information (peak voltage and impedance; $R$ and $X$) from the pre-filtered as well as ...