Questions tagged [measurement]

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19 views

Sampled AC Voltage measurement

I want to implement a AC Voltage measurement function for a DMM. That DMM can sample up to 1,000,000 Samples/s. With the sampling function I wanted to sample an input sigal (e.g. sine signal) and ...
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1answer
22 views

Is fft2 in MATLAB unitary? Some differences happen

I meet a problem when implementing fft2 in MATLAB. The question is I try to simulate the realistic measurements $Y = |FCXF^H|^2$ - the intensity of Fourier domain of object $X$, where $F$ denotes ...
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1answer
26 views

Phase measurement with FFT for DMM Keithley 7510

I am currenly working on a measurement driver for the DMM Keithley 7510. I implemented a harmonics measurement using FFT (from MathNet library). First I simply sample my input voltage signal and ...
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1answer
22 views

Separability vs. Resolution - Synonymous terms?

In terms of discrete representation of a variable, let's say time measurements in absolute values in [seconds], is there a difference between separability and resolution? When do speak of either ...
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0answers
15 views

Methodology for log some sweep audio measurement impulse response

I am trying to implement a method for measuring the response of a loudspeaker in a room using a log sine sweep stimulus. To check my method: 1. I create the stimulus using: Make recording length ...
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20 views

Log Sine Sweep Acoustic Measurements

I am currently trying to understand the Sine Sweep Method for taking acoustic measurements. I am following this paper: https://www.thinksrs.com/downloads/pdfs/applicationnotes/SR1_SweptSine.pdf I ...
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1answer
59 views

Finding period of a square wave with varying sampling frequency

I have a square wave (0-1.8V) with a varying sampling frequency (from a circuit simulator). It is also not a perfect square wave (the high and low signal could be very close to but not precisely zero ...
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1answer
40 views

Can I use SINAD for THD+N measurements? Are they inverse of each other?

I'm looking for a clarification, which I haven't really been able to find. It's probably obvious but I'd like to be absolutely sure of what I'm calculating. I noticed that the formula that calculates ...
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0answers
43 views

On-target SNR measurement

I want to measure the performance of a receiver demodulation algorithm, something like Bit Error Rate as a function of the power of the incoming signal (in dBm) and compare it to simulation results. ...
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1answer
57 views

Sensor rise time compared to experimental step input rise time

I have a dynamic calibration system. With it, I am applying a experimental step input to a pressure sensor. The goal is to measure the step response of the sensor and use it to calculate the frequency ...
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0answers
81 views

Phase response of S11/S22 parameter for an RF attenuator? [closed]

I am new into the RF measurements. I was measuring the S11/S22 (reflection) parameters of an RF attenuator (with different attenuation levels, e.g., 10 dB) via a vector network analyzer from Rhode &...
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3answers
109 views

Quality of experience engineer

I have noticed certain overlap between digital signal processing and quality assurance for jobs that require expertise in evaluating the quality of the transmitted signals on telecommunication systems ...
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1answer
118 views

How to calibrate a signal with respect to frequency

I have recordings from accelerometers (non-flat response with respect to frequency) and I'd like to convert my voltage time series into acceleration values. Is there a standard method for doing this? ...
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1answer
98 views

Calculating THD where peaks are not exact harmonics

I have captured an FFT of a 1 kHz signal that I am generating using a WM8904 codec running at 48k samples/second connected via I2S to a ARM microcontroller (Atmel SAME70). It appears to have some ...
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1answer
158 views

Why is Error Vector Magnitude (EVM) measured as an RMS value?

I do understand Voltage/Current measurement of a Sine Wave is in RMS, as average yields a zero, and RMS gives a true 'DC equivalent' value. But I do not understand why an EVM measurement could be in ...
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2answers
31 views

Is there a way to measure each pixel's content in an image somehow?

Is there a way to measure each pixel's content in an image somehow? Like can I interpret each color as some kind of a single value, rather than a triplet? Perhaps I can think of them as $\mathbb{R}^...
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0answers
62 views

Calculating Transfer Functions From Harmonic Distortion Percentage

Hi I am working on emulating a piece of analog audio equipment and would like to be able to create a transfer function based on the measured percentages of harmonic distortion. I know that harmonic ...
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1answer
634 views

What's the difference between UQI and SSIM?

I'm studying image quality assessment (IQA) problem and I'm currently learning about quality meassures UQI and SSIM, I know UQI is a predecessor of SSIM, but they look exactly the same for me...
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1answer
206 views

How to calculate the entropy of random normally distributed samples?

I have a hardware device that outputs a normal distribution of readings. It's (fitted) parameters are mean = 35 units, std.dev. = 8 units and I read the values as 8 bit integers. I'm trying to ...
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0answers
124 views

Digital filter for sharp impulse in data

I am looking for an algorithm or a filter to remove sharp peaks from my data. I am collecting raw data after every 1 second from an sensor through an ADC. The ADC has an internal FIR filter. I use ...
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1answer
135 views

Estimating confidence intervals for the mean value

Say I conducted a numerical experiment -a time-dependent fluid simulation- and extracted a time-series of some variable. It looks like this: As a result of the simulation, I am supposed to report the ...
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1answer
89 views

Filter results from force measurements

I was provided with several force measurements. Precisely: The vertical compression force exerted from the milling tool on a working peace. The plot of the force looks reasonable and of course it ...
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1answer
445 views

Adjustment of window length with sliding/moving RMS method for frequency drifts

I'm using a sliding RMS mechanism to compute RMS of a signal, i.e. with a window size of N, I add the squared value of the new sample $x[n]$ to the running total while deducting the squared value of ...
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1answer
916 views

Measuring signal phase difference between receivers

I am working on a project which aims to locate a transmitter. I consider doing this using several receivers and measuring the phase differnces between them. My problem is that arduino measures once ...
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0answers
44 views

How does the error in azimuth angle vary as one moves away from the boresight direction of a radar

My question is basically same as the title. I am trying to find a mathematical model which provides the error, $d\theta$, in azimuth angle($\theta$) as one moves away from the boresight direction of ...
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0answers
43 views

Parameter estimation from a measure

I'm doing an exercise where, given a data sample taken from a physical measure, I have to estimate the parameters of the measure where samples $x_i$ are described by the equation: $$ x_i = A \sin(2\pi ...
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1answer
67 views

SNR problem with different sampling rates using innerproduct

I'm trying to measure the amplitude of a sinusoidal component in a noisy signal. Since the signal frequency is known beforehand, I'm calculating scalar product with a sine and cosine base function ...
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0answers
70 views

Why is the term deconvolution used more for signals and not so much (or at all) for systems?

Wikipedia defines mathematical deconvolution here, and with the examples given and my experience, what I've read over the years is that deconvolution is used to determine an input signal provided a ...
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2answers
303 views

Measuring amplitude of a spectral component

I'm trying to measure the amplitude of a spectral component in a signal. The component's frequency is always known beforehand. I take a given number of samples, apply the flattop window to reduce ...
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1answer
139 views

Best reference for object size estimation in an image

I'm working on a project where I need to measure the size of a 2D object on a flat surface from an image. I have total freedom to create a reference with any shape and size. The camera I am using is ...
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0answers
377 views

Sampling and zero crossing

I am sampling a sine wave of 50Hz(stepped down from 230V) at the rate of 500KHz. For identifying disturbances in the wave, i was thinking of comparing a cycle of incoming sine values with reference ...
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0answers
131 views

White noise sound vs harmonic sound reverb

I use a microphone array to localise a sound source in a small lecture theatre. I tested it with white noise and a bird noise source. I found out that the white noise source give very good results. ...
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0answers
17 views

How is per-class rate defined?

I've recently read the following For our pixel labeling, consistent with [20], we report the number of pixels correctly classified (per-pixel rate) and the average of per-class rates. The per-...
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1answer
37 views

Accurate measurement of object's position on a bayer-filtered and grayscaled images

This is an experience-related question about cameras and image processing. I have a laboratory setup. Under some simplifications it looks like a red ball rolling on a white table (the real setup is ...
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82 views

Get the distinctive deltas of quite noisy and very variable / dynamic measurement values

for my thesis I need to point out the distinctive deltas of my measurements for further use. The jumps can occur with different heights over different time slots. And the absolute base values can ...
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0answers
27 views

If a signal is added to another in the freq. domain, how to filter it out?

I have two signals, $x$ and $y$. I know that $F(x)=F(s)+F(n)$ and $F(y)=F(n)$, where $s$ is the 'clean' signal, $n$ is the added noise and $F$ donate Fourier Transform. To obtain the clean signal, I ...
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2answers
60 views

Finding filaments in high dimensional space

I have unit vectors in a high-dimensional space (~300) that are non-uniformly distributed over this hypersphere. There is physical meaning when the vectors are clustered together, but I'm ...
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3answers
619 views

Measuring non-planar objects in image

I'm working on a computer vision application (using openCV) and the goal is to measure the width of an object before/after it falls on a container. So after the fall its position will be random, ...
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2answers
894 views

Digital low-pass filters; best practice application

I have time domain strain gauge data from a structure which is subjected to low frequency, random loading. The signal / noise ratio is pretty good, but I would like to try to improve on it as much as ...
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2answers
287 views

Why these harmonics always present?

I am using Audio Precision 2700 to test some test vectors. I have connected resistor banks as class - d power amp's load, and tap from this resistor using a XLR cable to the AP. When my power amp ...
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1answer
460 views

Measuring the similarity of two waveforms [closed]

I have two approximately sine truncated waveforms of different amplitudes and I want a numerical measure of how similar they are to each other. I am sending a sonic pulse train whose multiple ...
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0answers
143 views

Image objects dispersion and diversity measures

I have images like below: I want to find some measures describing black spots dispersion and diversity. First measures I use are mass center off all black spots, mean area of spot, stdev of area ...
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2answers
445 views

measure angle between two lines, can rotation center constraint be used to refine the initial measured result?

I'm trying to measure the angle between two needle positions in an analog meter (gauge). such as: After the image processing of several images, I get the processed image below(a image show different ...
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1answer
67 views

what is standard acoustic volume

In Audio Experts book, it's given as Sound pressure meters must be calibrated at factory to a standard acoustic volume. So what doth this ...
2
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1answer
261 views

Digital Vs. Analog Phase measurement [closed]

I'm working on a Ultrasonic Transducers resonance tracking system. Where phase shift between Voltage and Current is the feedback signal for my system when phase difference is Zero that means system is ...
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0answers
2k views

How to convert raw pulse sensor data into actual pulse?

I've built a simple device, which sends readings from a pulse sensor to a PC. I get these data: What technique or algorithm can I use in order to calculate the pulse rate (beats per minute) from ...
5
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1answer
287 views

Received Morse Code signal-to-noise ratio?

I have some digital recordings of some received over-the-air CW broadcasts of known plain-text (W1AW code practice) at known WPM code speeds, but in moderate to heavy RF noise and fading. Can I ...
5
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1answer
581 views

Compare image segmentation approaches

I've got a question related to a comparison of image segmentation algorithms. I'd like to compare two algorithm results to each other in step one. In another step I'd like to compare the two ...
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1answer
557 views

Accuracy of Goertzel algorithm for measure harmonic

If I use Goertzel algorithm for calculate the magnitude of current or voltage, use for measure current harmonic or voltage harmonic or fundamental component. I not use for detect harmonic. Do you know ...
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3answers
5k views

How to detect “fast” changes in signal processing

I'm working on a project where we measure the solderability of components. The measured signal is noisy. We need to process the signal in real time so that we are able to recognize the change that ...