Questions tagged [sensor]

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Get IMU acceleration of a direction when tilted

I have an IMU that is placed on the body. My goal is to calculate the position data of the vertical upward movement. Since the sensor is never perfectly aligned and will always have a little tilt, I ...
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1 answer
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Understanding shifts and superpositions in vibration sensor data

I’m looking at some measurements for elevator door vibrations from this dataset (a cleaned version of what is available here, as I understand it) and, if I plot the series of measurements, I get the ...
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1 vote
1 answer
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getting a smoother real-time frequency estimate using the phase for a triangle wave

I'm using a phototransistor and an optical chopper to measure the angular velocity of a wheel, much like how mechanical mice used to work. The signal looks like a triangle wave with some noise in it, ...
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3 votes
2 answers
167 views

Detecting bullet holes using Python with camera or sensors

I am trying to build a system to detect bullet holes in paper. I've read many StackOverflow threads but not a single one satisfied me. Current methods, which I am using, are good but not perfect and ...
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1 answer
30 views

Minimizing Integration Error in an Accelerometer

I am trying to use an accelerometer in an IMU (ISM330DHCX) (integrating to get position). To do this I need to fix the calibration error. Ideally the integral of the accelerometer values while static ...
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Adaptive Particle Filter: unknown process Equation

In my design and implementation of a SIR particle Filter, I don't have the state process equation of the actual system, which would have given a very good estimation of the real signal. I was ...
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2 answers
719 views

What sensors can be fused using the Kalman Filter framework

I was recently introduced to the concept of Kalman filtering in the context of projectile tracking. A classmate recommended this to me, and what intrigued me most was its ability to fuse different ...
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1 answer
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SNR estimation from a radar sensor signal

I am using a radar sensor for human activity monitoring which works on 3.18GHz. The received signal by the receiver of the sensor depends on the movements in its area of observation. All the activity ...
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3 votes
2 answers
135 views

Kalman Filter Motion model with moving sensors

Suppose I have an object that I am tracking with moving sensors using a basic Kalman Filter (for example, think of a ship being tracked by satellites). In the simplest case where the sensors are ...
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Best way to reach experts in the Synthetic Aperture Radar (SAR) Simulation field?

I'm looking for Synthetic Aperture Radar (SAR) Simulation experts and struggling to find them (context: synthetic data for geospatial applications). I've found a few users in this community who could ...
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0 answers
19 views

Smartphone acceleration data to path

I try to calculate smartphone path based on acceleration data. I drew a triangle on the table using my device and now I want to generate a path. I use following formula: ax = (ax[i] + ax[i+1])/2 ay = (...
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1 answer
100 views

Clustering FFT frequency bins from sensor time series data

I am trying to analyse multivariate time series data sets. I have 6 signals for each event, representing 3 linear accelerations and 3 rotational velocities for a 40ms window. I am trying to find a way ...
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1 vote
1 answer
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sensor data windowing and normalization

I am getting up to speed with working with sensor accelerometer data. I am looking to conduct a FFT on this signal. I found that the signal being non periodic is causing issues so I have tried to look ...
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1 answer
76 views

Kalman filter for heading estimation with magnetometerv + gyroscope only considers magnetometer

I implemented a Kalman filter to estimate the heading of a robot that is moving in 2D, given the measurements coming from a magnetometer (X, Y) and a gyroscope (Z). The code is the following: ...
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0 answers
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Using lock-in amp to measure pulsed signal

I am working on a design of an acoustic resonator for sensing application, I use an excitation field at a certain frequency (a), and measure the response of the sensor (b), for my application, I only ...
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1 answer
52 views

Time-frequency analysis of a nonlinear system

I have empirically developed a sensor failure detection system which works fine. The system receives inputs from different types of sensors. Because of noise characteristics, I use low pass filters on ...
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0 answers
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Optimal fiducial marker design for signal registration

I have scalar, time series data being produced by a set of measurement devices. For simplicity, assume that all the devices operate at the same sampling frequency (I can always interpolate if not). ...
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94 views

How to determine sampling rate of a lock-in amplifier?

I am trying to figure out the sampling rate of a lock-in amplifier and how it is related to the time constant. For example, imagine measuring sinusoidal waves at $1$, $5$, $10$, and $50$ Hz ...
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125 views

Space-Time Finite Element and Static Condensation for Sensor Fusion

My recent pastime interest deals with the nonlinear sensor fusion of GNSS, barometer, magnetometer, accelerometer and gyroscope data. I had a look at the EKF, UKF and Particle Filters but gave up as ...
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1 vote
0 answers
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How do I turn my sensor samples into a cleaner, more useful curve?

This is for one of my fish tanks, which has dimmable LED lights. It's a bit of an experiment where I'd like to see what'll happen if the "sun" above the tank "rises" and "sets&...
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-1 votes
1 answer
48 views

Trying to do frequency analysis of an accelerometer output

I am new to signal processing. I have a 3 axis MEMS accelerometer. I have read its output into $\mbox{Matlab}^{\tt TM}$. My problem is that the signal I am trying to isolate has a frequency of about 0....
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1 vote
1 answer
69 views

FFT requirements of real time signal from sensors

I have an electrical current sensor which generates measurements every second. I want to calculate the FFT of this signal. Since my real-time values are received every second, I think that the fastest ...
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1 vote
1 answer
675 views

Kalman filter with multiple sensors

I have been reading more about EKF and I am a bit confused on how you handle predictions with multiple sensors. Ex, I have IMU, GPS, Odom and Stereo Camera. Each can be used to predict location, how ...
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1 vote
0 answers
115 views

How to get a depth map from a Kinect 360 depth sensor?

I'm trying to understand how Kinect 360 depth sensor works. At the moment, I know that this sensor is composed by an infrared pattern generator and a infrared camera. IR camera gets the pattern ...
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0 answers
20 views

Accelerometer drift: What hardware-level signal conditioning operations are being performed under the hood of a MEMS accelerometer chip?

I'm in a debate with a peer who says that filtering accelerometer signals at the chip-level has nothing to do with mitigating the problem of drift Often, additional software-level filtering is ...
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3 votes
2 answers
85 views

Speed from Depth/Pressure sensors

I have a pressure based Depth sensor. For reference, MS5837-02BA. All depth measurements I've been able to read are very accurate (±1cm) I tried experimenting to find out the speed of the body by ...
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1 vote
3 answers
400 views

Averaging data from 2 sensors

Suppose we take a reading of a single rotating axis using 2 identical sensors. Intuitively, I think that averaging the outputs of both sensors will yield a less noisy result. But what if sensor A has ...
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1 vote
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Using a Kalman filter to clean acceleration data

I am collecting acceleration, gyroscope and magnetometer data in all 3 directions. I would like to filter noise from the accelerometer using a Kalman filter. I am not trying to esimate orientatoin or ...
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3 votes
1 answer
60 views

How significant is the time lag between inertial IMU data in a inertial analisys?

I'm working on a MCU system that use an IMU (ICM-20948) which has two different chip inside: one provides accelerometer and gyroscope data at $1125$ Hz (configurable at $125$ Hz), the other one ...
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1 vote
1 answer
235 views

Finding Minimum SNR or Minimum Detectable Signal Based on Noise Spectral Density

Imagine I have an $n$-bit sensor, whose noise spectral density is $V/\sqrt{Hz}$. $V$ is an exemplary measurement unit. The desired measurement bandwidth is also known. Is there a mathematical way to ...
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1 vote
1 answer
50 views

Accelerometer Inference from power spectrum

I have 3d accelerometer data sampled as 60hz. When I am looking at the power spectrum in all three accelerations (x,y,z). I am noticing a trend with a negative slope. I trying to figure a few things ...
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0 votes
1 answer
169 views

What is the driving Voltage?

While I was looking into ultrasonic transducer in order to transmit and receive a beam, I came across specification of a transducer stating driving voltage as 20Vrms. I am not sure what actually does ...
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0 answers
19 views

Equalization of ultrasonic transducer [duplicate]

I am working with ultrasonic transducers with frequencies 100 kHz, one for transmission one for reception. The transmitted signals are chirps. I would like to measure the time of flight between ...
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0 votes
1 answer
24 views

I want to get tilt sensor value for a given time t_0, but the tilt sensor data points are discrete. How do I interpolate between the discrete points?

I have 3-dimensional readings from a tilt sensor (specifically these are rotational angles about X, Y, and Z axes) over time. Let's call these angles S. I want to infer S at a specific time t_0, but ...
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0 answers
28 views

Extracting time-tagged pulses from Geiger audio recording

I am doing some tests with SmartGeiger detector designed for smartphones. The sensor unit sends pulses via phone microphone jack input and the app does the counting and calculates the values. However,...
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0 votes
3 answers
343 views

Is it better to use sampling rates which are a power of 2? 32-64-128-256-512Hz? instead of using for example 30- 60-100-250-500Hz?

I am recently working with a sensor that I its sampling frequency can only be configured to either 32hz- 64hz- 128hz-256hz... and I was wondering whether using such sampling frequencies have any ...
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0 votes
1 answer
78 views

Estimating Real-Time Vehicle Velocity from low-frequency GPS, accelerometer, gyro and magnetometer in Smartphone

I am trying to write a system that would be able to estimate the velocity of a traveling vehicle (usually a car) using a smartphone. Most smartphones have the next sensors: 1Hz Low-Frequency GPS 10-...
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0 answers
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What does Allan variance really means? [duplicate]

Let a sensor (e.g. accelerometer) with a combination of white gaussian noise and random walk noise. The loglog plot that is usually shown as function of a time parameter, affine decreasing for a ...
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0 votes
1 answer
340 views

How to understand the sum of all "fourier frequencies"?

I got the data of an acceleration sensor to analyze. It consists of special terms of 30 Hz, 60 Hz and 120 Hz. In the following you can see in the first plot the 60 Hz data and in the second one the ...
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0 votes
2 answers
39 views

Can amplitudes be used to differentiate one signal from another?

I have use case, where there are lot of sensors placed under ground.The sensors give amplitudes each second.So my aim is to detect if some anomalous activity takes place at that point. IF an activity ...
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0 votes
2 answers
1k views

Fourier transform of a noisy signal

Let's suppose i have a sensor that measures the output of a process and this cause a not negligible noise that affects my signal. My goal is to analyze the process signal in order to find faults. How ...
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1 vote
0 answers
37 views

SciPy - Distinguish between two group of periodic samples [closed]

First of all, I'm sorry for my bad English writing, plus, I'm new to DSP. Background We have got motion data of 20 cows. 10 cows are healthy and 10 cows are slightly lame. Lameness is an abnormal ...
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0 votes
1 answer
44 views

How to get discrete values from a nosiy data set that have a trend?

I have a sensor that produces values over time (appr. 50/sec). I visualized these values (X axis is the time), this can be seen on the picture, measurement A and B - these are two independent ...
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0 votes
0 answers
54 views

pressure decay filtering

So, I've been dealing with a series of pressure decay curves from a pressure transducer. Each one has a waterhammer effect as a consequence of shutting down pumps. Here are examples of 3 curves: I'm ...
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0 votes
1 answer
436 views

Getting Vario (m/s) from a bmp180

I am building a variometer as a hobbie, this could be a duplicate from an existing question: How to use Kalman filter for altitude prediction based on barometer data? . Details follow: I have a ...
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2 votes
1 answer
310 views

Reduce noise of sensor by combining two

I've had the basics of signal in university but little real-life practice. I've got an acceleration sensor with a digital output signal (signed 16 bit value). This signal is a little noisy. The ...
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1 answer
166 views

Inverting Sensor Transfer Functions?

When you see software packages that read in data from sensing equipment, does the software do something to inverse the transfer function? Correct me if I'm wrong in my understanding, but this is how ...
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1 vote
1 answer
768 views

Kalman Filter - How to combine data from sensors with different measurement rates?

I'm trying to implement a Kalman filter for tracking the position of a vehicle with the help of position data from GPS and Odometry measurements. The GPS data (WGS84 format collected from an app on an ...
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2 votes
2 answers
2k views

Minimum sample frequency of IMU accelerometer and gyroscope

I was wondering how I would justify a sampling rate of 125 Hz for accelerometer and gyroscope data from wearable sensors. This is a rate used in a lot of biomechanics literature, but I can't seem to ...
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1 vote
0 answers
102 views

How to draw a smooth spectrum from a discrete array of measurements at selected frequencies?

I have a AS7265x triad spectroscopy sensor from SparkFun (link) which gives me measurements at 18 individual light wavelengths between 410nm and 940nm. The datasheet says that the FWHM of each sensor ...
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