Questions tagged [detection]

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1answer
51 views

Find gaussian in data

I have some time series data (blue line lower plot) with a gaussian added into it (red line upper plot). I would like to estimate where the gaussian is in the data, and the height of the gaussian (...
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0answers
39 views

How to perform signal detection in white noise?

We have a signal $s[n]$, given by the autoregressive model: $$s[n] = as[n−1] + u[n], n = 0, 1, ..., N − 1,$$ where $a$ is a real number and $u[n] \sim \mathcal N(0, 1)$ follows a normal ...
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45 views

Maximally Stable Extremal Regions (MSER) Implementation in Document Image Character Patch Identification

My task is to identify character patches within the document image. Consider the image below: Based from the paper titled "CG-DIQA: No-reference Document Image Quality Assessment Based on ...
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1answer
68 views

Projecting a vector to another to detect the sparse values of such vector

Assuming we have sparse vector of length $N$ such as $X = [0,1,0,-1,0,1,1,0]$ which has some non-zeros values. The vector $x = iFFT(X)$ is convoluted with another vector $h$ resluting $y = h*x$. ...
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3answers
99 views

pitch detection: which is the most robust way to distinguish voiced from unvoiced audio

I am trying to write a voice/whistle driven synth but I am struggling with pitch detection. As a premise I must say I am quite skilled and experienced at dsp coding plus I have pretty read almost ...
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1answer
45 views

Detect low power DSSS-BPSK signal

I have heard that it is possible to detect a low power (ie not visible on a spectrum analyzer) DSSS-BPSK (direct sequence spread spectrum) signal even when you don't know the spreading code by ...
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1answer
56 views

Absolute value based AM envelope detection viewed in the frequency domain

In my understanding when a passband AM signal is demodulated with an envelope detector taking the absolute value restores the original baseband version of the signal and the low-pass filter removes ...
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0answers
38 views

lock in detection based denoising using matlab?

What are the limitations of implementing the lock in detection technique in matlab? I have time varying data with known frequency with huge background noise. The reference signal is also available. ...
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1answer
35 views

Synchronize device to audio stream - Approach

I am working on a device which's actions should be synchronized to the audio played. The audio stream is known in beforehand and can be altered to contain signals for the synchronization. But the ...
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1answer
45 views

What is the type of each 4 different noise signals that are shown below?

Dear signal processing experts, I am looking at four different noise signals.I got them in a time domain and they are different. I went to the frequency domain and found the fft for all four signals....
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1answer
162 views

Radar signal processing flow chart

I'm new to Radar in general, and I'm studying RADAR using online resources. I came across the following slide which shows the process flow of the Radar signal processing. The thing I don't get in ...
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0answers
54 views

What algorithm to use to detect musical notes of a flute?

I am trying to figure out how I can detect the pitch of 20 musical notes from a flute signal. I used the YIN algorithm, CEPSTRUM, SWIPE but they don't seem to detect but one note. Then I tried to ...
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1answer
515 views

How do I measure the amount of information within an image?

I'm trying to find some information threshold that is required for performing detection of objects in images. However, I'm not sure how exactly to quantify the amount of information contained within ...
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0answers
98 views

Generating a colored waveform of an audio file?

I would like to ask on what approaches could one attempt to generate a colored waveform out of an audio file. Below are two examples of waveform coloring by commercial products along an audio sample ...
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0answers
64 views

Threshold for CAF Surface

I am calculating a time partitioned Cross Ambiguity Function (CAF) by adding the surfaces of different time-sectioned CAFs together. Meaning, I calculate a CAF using 10 seconds of IQ data, calculate a ...
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1answer
106 views

Does flat surface detection and orientation require special hardware to compute?

Modern augmented reality platforms such as Google's ARCore and Apple's ARKit seem to only operate on mobile devices, I'm guessing, because their underlying algorithms require specialized hardware that ...
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0answers
258 views

How to set sigmas and kernels for 3D-Laplacian of Gaussian filters to blob detection in Matlab?

I have written code according to a paper for Lung CT images, but its output wasn't correct. I think it is because of the setting of its parameters. The paper is about a multi-scale method using a ...
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1answer
312 views

CFAR Detectors and Interference

Constant False Alarm Rate (CFAR) is an automatic thresholding technique. It's situated after the FFT processing in other to detect target peak. This probability of detection depends on clutter and ...
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1answer
33 views

Voice masking for removing voice and not birdsong

First the problem I'm tyring to solve: I'd like to find a way of removing any potential noise from audio files recorded in noisy environments where we are trying to record birdsong. This is for the ...
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3answers
3k views

How detect signal from noise?

I'm trying to detect when a signal is "on" from samples I have. Those samples come from a software defined radio, if that matters, and the signal i'm trying to detect is a WiFi signal. The problem is ...
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1answer
182 views

Pulse duration detection

I have a signal sequence where multiple pulses with different amplitude and duration may occur at random times. White noise is present as well. I was searching for a Matlab function which could detect ...
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1answer
606 views

Probability of False Alarm versus SNR

I'm currently testing the performance of an energy detector using two tests. One test involves finding the optimal threshold to achieve a probability of detection(Pd) of 0.9 and a probability of false ...
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1answer
392 views

Getting started with wavelet-based real-time anomaly detection for temporal signals using Python

I have an anomaly detection problem I wanted to consider addressing in software (python) with wavelets. I’m new to wavelets as well as the python’s spicy.signal wavelet package, let alone with the ...
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1answer
42 views

How to choose good features for my machine vision application? [closed]

I am trying to create an application (with OpenCV3) that can distinguish sidewalks from streets by a real-time camera that is embedded in a glass. I have 3 question about this project: Which features ...
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1answer
578 views

finding frequency range and dominant frequency of a stored signal

I have sEMG signals, captured from commercially available device. the signals are stored in .tdms file format. i want to varify whether the captured signals are really sEMG (or simply EMG) signals or ...
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0answers
133 views

Unbiased estimation of square in presence of Gaussian noise

I have a single scalar observation, $y$, of a scalar parameter $x$ in presence of additive Gaussian noise. That is $y = x + n$ where $n$ is the Gaussian noise. The variance $n$ is known to be $\sigma^...
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1answer
30 views

If I line in the sound from a video game console, can I detect when a sound is played?

The question is as the question is. It won't be this isolated sound though, it'll be a sound on top of background music. I think I can get a hold of the sound file itself from the data, but at worst I'...
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2answers
961 views

How to reliably detect the state (opened or closed) of sliding doors from a statically-positioned video stream

I have a mounted (static) camera that has a view of a set of sliding doors. Since doors are rectangular in nature, and they don't have many degrees of freedom, this seems like a problem that should ...
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2answers
1k views

Detect marker orientation inside an image

I've been reading how augmented reality works and how markers are detected. Anyway I can't find any resource that would help me in detecting an arbitrary complex image as, for instance, a book's cover....
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0answers
84 views

Another pitch detection problem

I'm a french student and I have to make a scientific project in group, so we decided to work on how automatically turn sheets music when a musician reaches the end of the page. For that I'm working on ...
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1answer
1k views

How to determine the symbol rate of a 2-FSK signal?

Let's say that I have a 2-FSK signal recorded so that the SNR is around 20 dB and the noise seems to be more or less white. The distance between tones is greater than the minimum distance needed for ...
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1answer
2k views

How do spectrum analyzers detect peaks?

Using peak search, I'm able to put the cursor on any of the several peaks on the spectrum analyzer display. I am trying to do something similar in software, with the output of the FFT of the radio ...
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1answer
815 views

What's wrong with this Average Magnitude Difference algorithm?

I implemented this Average Magnitude Difference algorithm in Javascript ...
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1answer
178 views

Is image processing impacted by the lens or sensor size of the camera?

We want to configure a system for detecting and tracking basketball shots made. We have control over the cameras, so we can choose anything from a smartphone to a GoPro. Assume the scene is a typical ...
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1answer
230 views

Detection markers in images

I have a set of images with red, round labels on it. What I want is, to get pixel location of each of the label. One way, of course, would be to search for red color pixels. But the problem is, ...
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2answers
2k views

Envelope detector for non-zero mean signal (Matlab)

I used hilbert transform to get an envelope signal. envelope = abs(hilbert(inputSignal)) This works for zero-mean signal: But, for nonzero-mean case, ...
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3answers
216 views

Are radar resolution and detection capabilities not very tightly related?

Radar detection capacity is the capacity to determine the presence or absence of targets whereas the resolution is the capacity to identify two closely separated targets. If you can detect the target ...
2
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1answer
429 views

Face Recognition: Simplistic Explanation on PCA Eigenface Algorithm

I m working on a project that I have to use eigenface but I have some uncertainty and I dont know how to deal with it. There are some tutorials about it on internet but I can't understand what exactly ...
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0answers
107 views

Detecting special points in signal

What tool/filter/mathematic operation would you use to detect the red points marked in this signal? As you can see there are several differentiated groups and I want to detect those moments in which ...
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0answers
95 views

Target detection for UAV landing

I would like to detect and track the following target to land an UAV. Target size is $1\rm m \times 1\rm m$. I have tried SIFT + FLANN but there is too few keypoints to have a good match. Have you ...
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0answers
584 views

How do we detect presence of background noise in audio?

The problem I am facing to solve is detect background hissing or humming sound in any audio stream. The audio stream can be of any type ranging from movies to talk shows. The background noise is ...
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0answers
278 views

Save ROI and background in two images

I'm using MATLAB Training Image Labeler app for labeling images and exporting the regions of interest (ROIs) which I save in .jpeg files.The ROIs are exported as a structure $1\times 430$ with two ...
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0answers
53 views

Annotate a dataset of images

I'll be recording a new dataset using a couple of sensors: kinect, stereovision cameras.. for a project for people detection using only depth information. But I don't know yet how can I annotate the ...
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0answers
1k views

detect what is noise in audio signal

I'm trying to filter noise from an audio signal. The signal was and is going to be recorded in a city environment which always contains some white/pink noise. At this moment I'm using two options to ...
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2answers
2k views

Object detection in binary image

This task comes from tracking object on a steady background. So far I was able to remove the background and obtain binary masks like this: I need to get bounding rectangle of the toy without the ...
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1answer
503 views

Audio Broadband Noise Detection

I have to quantify the broadband noise of an audio track. I've seen lots of things around and the only viable option to estimate the broadband noise (without having any information about it) is ...
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1answer
348 views

Best DSP algoritms for ultrasonic background noise cancellation

I am looking into detection of pressurized gas leaks by means of the broadband hissing sound (white noise) generated from pressurized leaking gas. The instrument will have a broadband microphone ...
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0answers
157 views

How to properly detect segments in a LCD segment display

I have been given the task to develop a code which checks if the display of a device is showing information correctly (i.e. any segments are activating when they are not supposed to). To meet this ...
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1answer
654 views

how to detect short pause in a speech with noise?

I would like to count the number of short pauses in a speech and know the duration of the pauses by loading the signal into Matlab but I am very new to Matlab. Can anyone help and give me some ideas ...
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0answers
121 views

Object localization down to the pixel

I am somewhat confused on the terminology used in Computer Vision. Suppose I wanted to detect (localize) an object (say, a human) in an image. However, a box around the human is not sufficient, what I ...