Questions tagged [sensor]

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Why is my pyrgeometer calibrated as if it has $a >1$ emissivity?

I've acquired an SL-510-SS upward-looking pyrgeometer. In the manual it gives the formula for how to compute the downwelling infrared it picks up: Clearly the $k_2$ coefficient is the emissivity of ...
• 1,215
28 views

Pressure sensors vs. piezoelectric sensors

In simple terms, what is the difference between pressure sensors and piezoelectric sensors? I did some google search online and could not come to a good conclusion. Say you make a 'sensor' in the lab ...
1 vote
90 views

If we know forces and torques applied to one point of a rigid body, how do we calculate them for another point of a rigid body

Suppose we have a rigid body with known length $r$ that is fixed at point $A$. We also have a force-torque sensor at point $A$. The body is fixed such that it doesn't move. We apply forces to point $B$...
1 vote
53 views

How does an airflow sensor work? [closed]

There are 4 piezoresistive sensors placed at A, B, C and D.
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Working principle of Shack-Hartmann Wavefront Sensor

(Image source: https://www.thorlabs.de/newgrouppage9.cfm?objectgroup_id=5287) In the Shack-Hartmann wavefront sensor, the local slope of the incident beam's wavefront is measured as a displacement of ...
1 vote
54 views

I bought a Digital EMF Tester Electric and Magnetic Field Radiation Detector here. At first, I thought it was a metal detector since keyboards (without being inserted into a USB port) cause alarm, ...
25 views

Deriving Azimuth Algorithm: Limitations of Accelerometer and Gyro Sensor Setup

I have a navigation device for which I am trying to derive an azimuth algorithm. I am getting stuck with the derivation, as I'm pretty sure it is impossible given the hardware I have access to. I'm ...
1 vote
16 views

Help with estimating odometry using two lidar sensors with known extrinsic calibration

I have a setup consisting of two lidar sensors with a known extrinsic calibration. Both lidars have messages with the same timestamps (no timedelay between them). My goal is to estimate odometry using ...
• 11
35 views

Is photon emission density is same or random everytime?

I want to know if photon density changes over time. By density, I mean number of photon hitting a surface in time. I am not asking about the direction of emission which is random. What I mean is that ...
1 vote
175 views

Calibrating an inertial measurement unit (IMU) to zero/flat surface

I am building a digital spirit level using an inertial measurement unit (IMU), and I want to calibrate the device so that it shows the angle correctly. Does anybody here have experience with this kind ...
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1 vote
40 views

Question regarding converting analog sensor value into mA [closed]

I'm doing a project with an absolute humidity sensor. When I bought an absolute humidity sensor and implemented it into a machine, I expected the output value to be representative of absolute humidity,...
38 views

Remote mass detection and location

Could a collection of gravitational sensors (eg. MEMS accelerometers), placed in a 3d grid (eg. 10 x 10 x 10 sensors forming a 1 x 1 x 1 m cube) detect the the presence and position of a remote mass ...
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What's the best way to measure a magnetic field?

I work in a physics lab. ...
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Can the receiver of an IR sensor pick up the signal from another IR sensor?

So I was trying to find a way to transmit a particular signal. I was thinking of getting one IR sensor to transmit a signal, which would be picked up by the receiver of another IR sensor. However, as ...
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Path reconstruction from accelerometer and gyroscope data

I found a dataset here whose columns are attitude.roll, attitude.pitch, attitude.yaw gravity.x, gravity.y, gravity.z rotationRate.x, rotationRate.y, rotationRate.z acceleration.x, acceleration.y, ...
1 vote
75 views

How can I determine how much energy a sensor pixel can withstand before exploding? [closed]

I am trying to design a camera system to image a laser beam. I know the sensor is a Sony IMX226, and I have the data sheet for this sensor. The data sheet, however, does not list a maximum energy ...
48 views

Which neutral atom-based quantum sensor is hardest to build/operate?

I am currently going through the presentation, "Sensing with neutral atoms", by Grant Biedermann. I understand that, according to the talk, there are a large number of different sensing ...
• 422
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In a light plasma, how many electrons pass through a given area

Assume you have a light plasma of about 10^5 particles per cm^3. The energy-density of the plasma is about 0.1eV (as in near earth orbits, see here: http://assets.press.princeton.edu/chapters/s9500....
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When should smartphone be declared as static using accelerometer reading? [closed]

I wish to know when should I declare an smart phone static by reading its 3 axis accelerometer reading. I have notice that modulo of all 3 axes gives 9.8 when ever smart phone is static. What does it ...
• 241
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How can one detect a device (phone) falling using its 3-axis accelerometer?

I am working on an Android app to use its 3-axis inbuilt accelerometer to find if the phone falls. I googled and found that if the following value is less than 2: $$a = \sqrt{x^2 + y^2 + z^2}$$ (where ...
• 241
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What does photon-limited imaging mean?

The following link is about Photon-Limited Imaging, https://engineering.purdue.edu/ChanGroup/project_QIS.html. Is there any definition of Photon-Limited Imaging. From the paper Photon-Limited Object ...
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Is it possible to obtain noise level in electrons using only one camera?

In the link, https://www.photonstophotos.net/GeneralTopics/Sensors_&_Raw/Sensor_Analysis_Primer/Photon_Transfer_Curve.htm there is one figured called Standard Photon Transfer Curve – Multiple ISOs ...
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1 vote
103 views

How does a sampling rate of 1ns equate to 15cm for an optical instrument?

I’m currently working with open source data captured by the NASA GEDI LiDAR instrument and I am applying a math model to it. GEDI’s sampling rate is said to be 1 nanosecond or 15 centimeter resolution....
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Is Daredevil's superpower conceptually possible?

The Marvel superhero Daredevil is blind but has heightened senses, enabling him to perceive the world around him to a far greater extent than a regular person. In his depiction in the Netflix live-...
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1 vote
48 views

Principle of operation of a Gyroscope-Free IMU

What is the principle of operation of a Gyroscope-Free IMU, or how can angular accelerations and velocities be measured with accelerometers?
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1 vote
1k views

What is the negative pressure?

I have vacuum pump connected to quartz tube and vacuum sensor, when the pump reaches it max value the sensor reading (-1 bar) and the analog gauge in the pump reach the max value which is (-1000mbar). ...
112 views

What is the intuition behind excluding the effect of gravity from accelerometer data

In the unit of accelerometer and linear acceleration, I see that accelerometer is angular and the linear acceleration is linear. There is the impact of gravity on the accelerometer. However, ...
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Is there any sensor that creates a visual image of magnetic fields?

I am working on a project where I am trying to create a magnetic tag that can be detected from $20 - 50$ cm away. Is there any sensor on the market capable of this?
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1 vote
395 views

The change of mechanical into electromagnetic waves and vice versa [closed]

I know that sound is a type of mechanical wave, so the human eardrum changes mechanical energy into electronic energy (impulses) so the information may be processed by the brain. Question: As ...
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Compute capacitance of planar interdigital electrodes

My apologies if this is not the right place to post a question like this. I am looking to do post-grad research study next year in the sensory field for sensing gases like hydrogen, nitrogen or ...
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34 views

PVDF sensor response time

I am trying to measure the voltage response from a high energy impact using the PVDF sensors. Here is a description of the experiment. I would like to measure the high impact energy on the aluminised ...
• 13
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Through-metal-wall Ultrasound sensor imaging?

A while ago, MIT published a paper that used a radar sensor to take a low-res image, and then they trained an AI model to convert the image into a human skeleton for through-wall human pose detection. ...
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1 vote
190 views

Does the size of CCD/CMOS of a telescope affects the magnification?

For a normal, traditional telescope, the magnification level should equal to focal length divided by eyepiece diameter, i.e., $$Res=\frac{f}{D}$$ So does the size of the CCD/CMOS the same as eyepiece ...
131 views

Why do the sensitivities of magnetometers and gravimiters have such strange units?

It looks like the sensitivities of magnetometers and gravimeters are usually reported with the units of $\text{Tesla}/\sqrt{\text{Hz}}$ and $\text{Gal}/\sqrt{\text{Hz}}$, respectively (where "Gal&...
66 views

Does a tuning fork's resonance frequency increase with a repulsive force on it in AFM?

I have a tuning fork sensor with a probe tip that would be used in atomic force microscopy. Am I correct that the quartz tuning fork's resonance frequency increases with a repulsive force on it and ...
38 views

Clarifications on the calibration of a magnetometer?

I've been reading up on magnetometer calibration (sensor fusion in general) recently and got confused about some things. To my understanding, hard iron effects (e.g. inductors and magnets) which are ...
574 views

How is measurement uncertainty defined / calculated (of a sensor or measurement)?

Textbooks and online sources often say the industry standard for uncertainty is given at a confidence interval of 95 %. This means out of 100 measurements, 95 would achieve the specified value and ...
60 views

Is there any way to differentiate UV light from visible or IR light?

I'm working on a small sensor system that responds to only UV light and I wanted to know that is there any way to differentiate between UV light and the rest of the spectrum like using lens if so then ...
1 vote
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Brightness Temperature layered atmosphere

I'm trying to figure out how to apply the radiative transfer model to calculate the brightness temperature Tb in microwave (Rayleigh–Jeans approximation) considering atmosphere and no scattering. If I ...
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How exactly does a (capacitive) humidity sensor work?

How exactly does a humidity sensor work? For example, how can it differentiate between a relative humidity of 30 % and 35 %? I know how a capacitance works but for me that principle is way too high ...
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What is a piezoelectric sorption detector?

I'd like to know what a piezoelectric sorption detector is. I can hardly find information about, only a small number of research papers which are mostly not accessable for me. Only given from the term ...
• 1,497
180 views

Measuring real time water usage with live water pressure monitoring

My home started seeing high water bills recently. My water company doesn't provide live water meter readings. There is a water meter on the street which I can monitor while water is being used but I ...
137 views

How does a weather station temperature sensor work? (physics behind)

In an automatic weather station, a temperature-measuring electronic sensor (which is typically 1,5 m in the air above a grassy ground and covered from direct sunlight) is in a certain way coupled to ...
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Any method to detect extremely weak electromagnetic wave signal? (10^12Hz, level ~10^(-28) Watt per meter^2 per Hz)

Could you please let me know whether there is any method on the Earth to detect some EXTREMELY weak electromagnetic wave signal, if it is a planar wave, if its exact waveform is completely known (...
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1 vote
38 views

Measure fluid speed by using a hot plate [closed]

I would like to figure out whether it is possible to measure the speed of a fluid by letting it flow across a hot plate. I was thinking about using the formulas for forced convection. The plate is ...
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1 vote
178 views

Accelerometer vs linear acceleration during an impact

I am trying to understand the relation between the accelerometer and linear acceleration during impacts. At work we have an accelerometer and gps onboard sensors installed in a few cars. The ...
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1 vote
1k views

Graph analysis of accelerometer data

I used my mobile accelerometer sensor to collect data from a moving bike where I held it in my hand in a way that the smartphone sensor +Y axis is in the direction of the moving bike always. This can ...
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What does it mean by (±20%) in sensitivity of a pressure sensor?

Sensitivity: (±20%) 15.5 pC/psi (225 pC/bar) this the sensitivity rating of a pressure sensor. what does it mean by (±20%).