Questions tagged [signal-detection]

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2answers
46 views

Probability of error for detection problem

Let $X \in \mathbb{R}^N$ and $Z \sim \mathcal{N}(0, \sigma^2 I)$ be random vectors. $Y = X + Z$ $X$ can be either $a_0 \in \mathbb{R}^N$ or $a_1\in \mathbb{R}^N$ with equal probability. So the ...
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0answers
11 views

Right approach for activity classification based on EMG signal?

I want to train a classifier that is able to identify different activities based on EMG data that is sampled at 41Hz with 8 channels, I read this paper that summarizes a lot of different approaches to ...
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3answers
58 views

best technique to remove noise from bio signal data

I'm still learning about signal processing so sorry if this is an intro problem. I want to remove noise from the following data so I can separate each wave and run analysis on it. The data is sampled ...
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0answers
29 views

Obtain SIB1 messages from CPRI the captured DL IQ data

I am a beginner in the signal processing, and I know some python and I have a project I'm working on which is about Obtaining SIB1 messages from CPRI the captured DL IQ data. I have captured some DL ...
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0answers
31 views

Strange signals in wifi channel

I am currently working with a USRP B200 mini-i to receive 802.11 signals from various usb wifi devices. When sending packets with the USB device over a channel, lets say 2.412GHz, i can't really see ...
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2answers
53 views

Can an audio recording tell whether it is made in a large or small room?

The conversation of one or more people will be analyzed. I think need to look for something similar to reverberation or echo in an audio signal. How can this be implemented? Update: small room is ...
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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
37 views

Proper HW circuit to decode PWM signal using Arduino Mini

I want to properly connect a Radio Control Receiver signal to a Arduino Pro Mini, Pin 11 so I can detect the 1 ms to 2 ms PWM signal. I calculate a value of 220 ohms will limit the circuit current to ...
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0answers
20 views

Understanding shift in Q values?

Can any one help me understand why there is a shift in Q values? It seems there is a DC offset/bias. How do I remove it or set it accordingly to make it equal to the I values/waveform? I am using a ...
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1answer
38 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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2answers
79 views

Pulse Doppler Radar: time delay in down conversion

My understanding of Pulse Doppler Radar is the system measures Time Of Flight for the pulse. My confusion is that during the down conversion process prior to ADC the lowpass filter causes some time ...
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1answer
48 views

Coherent Radar — How do we justify it?

How can we justify doing coherent radar when the phase of the return is unknown? For instance, after a reflection, assuming a stationary target, we should get something akin to: $$ x_{rx}(t) = |\...
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1answer
38 views

How to measure algorithmically side lobes in real data

I want to measure algorithmically the following parameters in a given FFT data (real numbers). peak side lobe levels side lobe levels 
side lobes nulls The following image illustrates parameters I ...
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1answer
23 views

I have the following accelerometer signal, I want to segment or slice the signal into Red parts and Green parts

I want to count steps which are basically represented by peaks in the signal. the red part in the signal doesnt correspond to any walking activity, I want to ignore them. Any help on segmenting or ...
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1answer
116 views

CIC Filter implementation for Normalized Correlation

This is a follow-on to the original post ... I am trying to implement real-time correlation of two signals. I noticed the CIC Filter discussion here: How to find correlation/cross-correlation of two ...
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1answer
44 views

Cone of Confusion

In sound perception, humans adapt by tilting the head or relying on other location cues such as visual input when the source of the sound lies on the cone of confusion. On this cone, no time and level ...
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0answers
21 views

interpretation of per survivor processing

Can any one explain me the interpretation of persurvivor processing, and how it is different from mlse,reduced state mlse,decision feedback mlse. What exactly meant by per survivor. Thanks in advance
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1answer
183 views

Correct comparison of FFT noise with FFT signal

I have a sensor which I am using to track a strong but noisy varying signal. When the signal is present there is a lot of energy in the FFT bins, when there is no signal the is much less energy - but ...
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0answers
31 views

Closed loop detection system

I am trying to design a detector of the DC component of a signal (low pass filter). I found the following topology (called Closed Loop Detection System) in an article (https://ieeexplore.ieee.org/...
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0answers
20 views

Detection time of a spur using FFT?

Say I have the following parameters, NFFT=2^14 Fs= 50 MHz main signal @ 22 MHz and its alias at 28 MHz at signal power -40 dbfs and a spur @ 2 MHz and its alias at 48 MHz Leave aside the alias's. ...
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0answers
25 views

Inconsistant Variation in BLE Beacon RSSI Values for Distance Measurement

I am developing an application to estimate the distance to a BLE Beacon using its RSSi values measured from a Mobile Phone. But when I started to collect data I could see that they varied so much that ...
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1answer
54 views

Algorithm for detecting whether a signal stored in rolling buffer is Increasing, Decreasing or staying Constant

I have a data signal which is generated at constant time interval. It is a real world measurement and thus exhibits some noise in its value (it fluctuates approx + or - 20 units). The noise is fairly ...
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2answers
724 views

How would you use machine learning for peak detection?

I have a noisy signal and I'm trying to find a way to detect peaks with ML. The "peaks" are easy to find as human because they are rhythmic and have the same "general" shape but the amplitude and ...
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3answers
564 views

How to Prove a System Is Invertible?

what i know is that for a system to be invertibel it should be one-one , but I am confused that if i am given a transfer function of a LTI system how can I prove or verify if it is invertible. ...
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0answers
42 views

MFCC parameters for gunshot recognition

I'm writing a gunshot detector software. I'm using this article as reference:https://arxiv.org/ftp/arxiv/papers/1706/1706.08759.pdf. For now, my software is able to recognize an impulsive sound. Now, ...
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1answer
44 views

Wireless Communication

Let's assume I send a root raised cosine pulse of 1ns at t=0 through a wireless channel. The power measured @ Receiver from t=0 is shown in image. Now from this image, I know that there are multipath ...
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1answer
88 views

Maximum likelihood estimation complexity computation

I have a basic question about maximum likelihood (ML) estimator and its implementation. I am trying to simulate a communication system, while using ML at the receiver side to find the transmit ...
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1answer
174 views

Time delay estimation between two complex signals(IQ)

I need to time align two complex signals. The two signals obtained were at different RF frequency before digitisation. So,I have two complex signals(IQ) and I need to do delay estimation and apply ...
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0answers
23 views

Is there a software/application that shows the FM base stations nearby us?

I want to collect a list of FM base stations near me. I have found apps/software for finding LTE base station but found no success in finding an app for FM base station.
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0answers
33 views

How to remove varying noise from strain data in MATLAB

I'm very new to signal processing. I have some data measured over time at 800 Hz. I'm interested in the high frequency signals. You can easily identify them in the image below (in this case, 3 signals)...
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0answers
61 views

Extracting signal from data using Otsu thresholding in MATLAB?

I am very new to signal processing. I am trying to extract a signal from my data using otsu threholding but it's not fully accurate. In this case I know that there is going to be a single signal in ...
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2answers
134 views

How to identify the beginning and the end of a signal using MATLAB

I have multiple signals as shown in this image. I'd like automatically detect time for the earliest detection of the signal (approx 0.7e4 in S1-B3-B (orange)) and last detected occurrence of the ...
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1answer
87 views

What are the limitations of using Magnetic induction rather than acoustic communication in underwater communication

In underwater environment, Why acoustic underwater communications are still famous more than magnetic induction communication however in magnetic induction underwater communication, higher data rate ...
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0answers
43 views

Is it possible to analyze this microphone data and what to do if not?

I just created an account here because I really need some help. I'm using a microphone pmodmic3 with a development board called Ublox C030-U201 which uses the mbed OS. The microphone is working for ...
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1answer
77 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
92 views

On the transmit weight vector in MIMO-MRC systems

Recently, I am reading paper [1]. In this paper, the author wrote: In MIMO-MRC systems in the absence of interferers, the signal vector at the received $n_R$ antennas is given by $$\mathbf{r} = \...
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2answers
304 views

Detection of sharp peaks in an audio signal

I have an audio signal and I'm interested to detect the very sharp peaks. If I zoom, here is something that should NOT be detected (this is voice actually): NO GOOD Here is something that should be ...
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1answer
154 views

Data transmission with SNR<0dB?

I encounter a situation that it is very beneficial to limit the signal strength below noise floor. I know that the Shannon–Hartley theorem suggest that it is possible: I searched over the internet ...
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5answers
567 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 ...
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1answer
74 views

Detection complex vectors by using correlation

I sent out a complex vector $x_i \in \{x_1,...x_n \}$ and receive a vector $y$. I use correlation $y^Hx_i$ to detect which $i$ was sent. If $y$ is corrupted by AWGN channel, the optimum rule should ...
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1answer
109 views

Multiplication and Convolution in Wireless Communications

In Wireless Communication, sometimes the received signal is expressed (in time-domain) as follows: $$r=hx+n$$ where $h$ is called a fading coefficient and sometimes it is expressed as: $$r=h*x+n$$ ...
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2answers
123 views

Signals - question due to sampling

I don't have an idea how to start it. Help pls :) $$m = z(t) + \frac{\operatorname{Sa}(t-T)}{4}$$ We have some signal $z(t)=\left(\operatorname{Sa}(\frac{t}{T})\right)^2$. How often the m signal ...
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1answer
88 views

Are there frequency detection methods that are subject to less latency than the Goertzel algorithm?

I am trying to detect oscillations in a small range around 1.5Hz as early as possible. I am currently using the Goertzel algorithm with bins 1.0Hz, 1.2Hz,..., 1.8Hz, and 2.0Hz; with block size N = 500 ...
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2answers
259 views

Homodyne and heterodyne detection

Very basic question here. I searched it on the net but cudn't get very convincing answers. Can anyone explain me Homodyne and Heterodyne detections in rf domain. Mathematically is much appreciated.
2
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1answer
120 views

Denoising a signal using eigendecomposition

I have a complex observable series $Y(t)$ which is the result of summing two complex r.v $X(t)$ (unobservable) and a $\epsilon(t)$ (unobservable). $$Y(t)=X(t)+\epsilon(t)$$ Assume that $X$ and $\...
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1answer
100 views

Where in the signal chain is Channel Equalization applied?

I am reading about channel equalization and I am somewhat confused on where in the signal chain channel equalization is normally applied and if it's before or after a correlator detector or matched ...
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1answer
51 views

Find identical audio signal

I have a long audio file (in wav) and a short audio file (in wav) that has been copied from the long file. Now I need to find the correct location where the short signal has been copied from. I tried ...
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1answer
114 views

How to programmatically find a sharp change in slope

First, apologies if I have the wrong group or this question is far too easy for this group. I am (as you'll see) a newbie. Please point me to another, more appropriate group OR tell me how to fix the ...
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0answers
60 views

ESPRIT signal subspace and rotational invariance

so in ESPRIT[1,2] we have some signal of the form: $$y[n] = \sum_{k=1}^{K} a_i(k) e^{j\omega_k n} + N[n]$$ where N is noise, then we get the autocovariance matrix $$R_{yy}=E[y[n]y[n]^*]$$ take the ...
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1answer
41 views

Detecting level in a Pulse Train

Assume I have a square wave pulse train, where each high lasts for H and each low lasts for L seconds. I sample this waveform and have the sequence of numbers. Question is what should be the sampling ...

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