Questions tagged [sensor]
The sensor tag has no usage guidance.
78
questions
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50 views
Would a speed camera register more speed if it moves in the opposite direction than the object it's measuring?
Earlier today, I was talking with my friend about speed cameras measuring different speeds when moving.
This is the situation:
I am the red car and I'm driving ...
0
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1answer
45 views
Basics of camera calibration
I tried to find some useful explanation about camera calibration and stereo camera setup in the web but was completely overwhelmed by the hairiness of the content: but seriously though, does it have ...
-2
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0answers
47 views
Sensing different forms of energy [closed]
Can someone indicate whether electromagnetic radiation can be felt by the human body? And if so at what frequency? And what are the effects of exposure to it.
Looking forward to your reply.
0
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1answer
29 views
Why photodiode measures random phase superpositions on continuous-wave (10kHz) white light?
I measured a 10 kHz modulated white light using a photodiode (Thorlabs PDA10A):
Unexpectedly, the photodiode output sensitively depends on the orientation and position of the photodiode. For two ...
0
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1answer
39 views
Unique optical map of a uniform metal object
Given a metal object (let us say a perfect planner uniform surface) that has been exposed to external environment factors such as sun, wind, rain and others for couple of years.
This object has been ...
0
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2answers
51 views
Measuring pressure or weight from an uneven weight distributed surface
I am new here so I hope I'm posting it at the correct place.
I am having some troubles with some of my force sensors. My case is like this:
I have a body which have a weight. However, the surface is ...
2
votes
1answer
37 views
Can a syringe be used as a hanging scale if needed?
FYI: This is not a homework q; I am just curious... You can assume that...
the syringe tip cap creates a "perfect" seal, i.e., keeps air from flowing in/out!
the syringe is completely depressed ...
0
votes
1answer
75 views
Estimate pendulum motion
I have a simple system: a pendulum and two sensors (RADAR which will tell the distance $dx$ and $v_x$ and a Gyroscope, the gyroscope is giving me the information about $\omega$ - angular velocity) as ...
0
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0answers
23 views
how to calculate concentration of a produced vapour from bubbler system?
We are working on metal oxide gas/vapour sensor. To pruduce ammonia vapour we are using bubbler system. we know the volume of the liquid, and flow rate of carrier gas. How to calculate/ measure the ...
1
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0answers
21 views
How to Measure Electric-Field Probe Sensitivity?
I am doing some reading on current methods for detecting electric fields. A figure of merit for the systems is, naturally, the minimum strength of field that can be measured, in units of Volts per ...
1
vote
0answers
39 views
Why does a cooking thermometer show different temperatures when touching the container of a liquid?
I have a cooking thermometer that looks like a 10-15 cm long metal rod, that can be inserted into the thing you want to measure the temperature of:
When inserted into boiling water, I observed that ...
0
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1answer
26 views
What are the magnitude of voltage fluctuations in field surrounding the human head?
How much would the scale of the electric field caused by neuron activity in the brain vary as it radiated from the scalp? Also what would be the typical noise level over the same space attributable to ...
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0answers
13 views
Methods for detecting when a semi-permeable enclosure is opened?
I'm looking for a way to detect the approximate volume of a semi-permiable enclosure such as a cardboard box or paper envelope - the objective is to determine when the enclosure is opened. Some of the ...
2
votes
1answer
49 views
When the barometer drops, my well level seems to rise - how?
I have a deep water well, with a length of 1/4" drip tubing, open at the bottom, taped to the pump 180' down. The other end of the tubing is connected to a gauge pressure sensor in the cabinet of my ...
0
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1answer
57 views
Phone accelerometer - formula to calculate angular gravity
I am taking readings from the accelerometer of a smartphone and want to account for gravity. My device reports residual gravity as "10g" (device stationary, screen facing up).
As the angle of the ...
0
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0answers
48 views
Need an equation to calculate the list of latitudes and longitudes of an off-nadir sensor with a given half angle
I need a deterministic way to determine a list of latitude and longitudes of an off-nadir pointing sensor for a given half angle. Below is a depiction of the problem.
It isn't too hard to calculate ...
0
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0answers
61 views
How to reduce measuring angle of JSN SR04T?
I wanted an waterproof ultrasonic sensor. So I used JSN-SR04T (NB: link to PDF document), imaged below. But the problem is it has huge measuring angle, 75%, which results in measuring obstacles which ...
0
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1answer
28 views
Piezoelectric powder solution to measure extremely high pressure
Idea - While reading about piezoelectric materials, I thought about mixing piezoelectric powder with silicon oil to measure extremely high pressures (of up to 4000bar).
Experiment - Consider a ...
2
votes
3answers
65 views
Why do sensors that emit higher frequency signals give more accurate data?
I am doing a technical presentation about RADAR and LiDAR. I understand that LiDAR is several times more accurate and capable of producing really detailed 3-D maps of their surroundings, while RADARs ...
0
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2answers
833 views
Calculating Velocity from Acceleration (Accelerometer)
I am using the Accelerometer in an Android Device to track and detect certain motions, using only one axis as the motions are linear along that axis.
I am using a simple filter to remove the noise ...
2
votes
2answers
3k views
What plastic-like materials allow IR to pass through them? [closed]
What plastic-like materials allow IR to pass through them?
Material should be solid and plastic like. Does't care if it is transparent to light or not.
IR ray is emitted by Sharp distance center so it ...
4
votes
2answers
66 views
Physical processes taking place inside Germanium detectors
Reading about differences between Silicon detectors and Germanium detectors, I decided to learn a bit more about the latter, since I've always used Silicon detectors in all the experiments I worked ...
0
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1answer
35 views
Keeping sensors at constant temperature
I need to measure the performance of some sensors with a strong temperature dependency. Later on, I will do some calibration for the entire temperature range, but for the moment I just want to do a ...
3
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1answer
240 views
How does the “Electromagnetic Position Tracking” work, exactly?
I've been searching the web for the technology of the "Electromagnetic Position Tracking1," and have found the web to be surprisingly ineffectual!
I've just came up with some preliminary and basic ...
3
votes
2answers
343 views
Inductive sensor - How does it work?
I can't understand how the system sketched here physically works:
4 = permanent magnet, with residual magnetization $B_r$
6 = ferromagnetic core with a coil around it
7 = ferromagnetic toothed ...
1
vote
1answer
608 views
Why can't I use a gyroscope/accelerometer only as a compass?
I am seeing this from the usual smartphone sensors. These sensors (Android here e.g.) take the magnetic field data as input. That is okay, but some phones do not have a magnetic field sensor (they ...
1
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1answer
178 views
Is surveilluminescence an April fool's joke or is the science legitimate?
This website and in particular this paper, describe how one can 'see' the 'sightfield' of a camera. To quote,
[A] linear array of computer-controlled LED lights is held in front of
a surveillance ...
1
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0answers
229 views
How can I calculate the sensitivity of a seismometer?
I would like to know how to find the minimum ground motion a seismometer can measure, specifically if a certain seismometer can measure 1 micron/sec velocity. I have a few specs from the datasheet but ...
1
vote
1answer
227 views
Is it possible to “override” the Earth magnetic field locally? [closed]
For a mobile application I am developing I would like to know which direction the phone is facing. In the outdoor we can of course use the magneto meter in combination with a gyroscope.
However, ...
0
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0answers
57 views
Is it possible to make an imaging array differential?
As described in this comment on a Slashdot post, exposing an imaging sensor to light accumulates charge in a well (i.e. pixel) on a piece of silicon. The well can only hold so much charge (release so ...
0
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1answer
177 views
Filter for RGB separation
Looking at Bayer filter of a typical consumer camera, one can easily see that sensitivity of the filter for each color is all over the place. Are there filters similar to Bayer that do a better job at ...
1
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0answers
266 views
Can I calculate the downhill force with the data of a smartphone sensor?
Apologizes for the long explanation, I couldn't find a shorter one.
I'm working on a project and want to calculate the downhill force only with data I can get with the sensors of a smartphone.
I ...
2
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1answer
2k views
What's the difference between proper acceleration and coordinate acceleration?
I'm not a physics student, but I need to understand these concepts in order to explain what exactly an accelerometer measures and not measures, and why. Please, do not explain to me what an ...
5
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1answer
156 views
Cosmic Ray Detection | Florescent Light Bulbs
Main: Can cosmic rays be detected through florescent bulbs?
Can you push an AC current through a florescent lightbulb tube and measure the current draw and voltage spikes to detect cosmic rays? Is ...
2
votes
0answers
177 views
Sensitivity of human eye v.s. photodiode or photomultiplier?
I am working with optical detectors and I would like to explain to friends how small 1 pW of optical power emitted at $\lambda$ = 550 nm is related to the sensibility of the human eye.
My idea is ...
1
vote
2answers
501 views
What's an accelerometer exactly measuring?
Take two different reference frames. The first one - say $\lbrace{W}\rbrace$ - is inertial and it's fixed to the Earth surface. The second one $\lbrace{B}\rbrace$ is moving and in general is rotating ...
0
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2answers
68 views
light point and photosensor
When a laser pointer is pointed at a screen or at a target that spot can be detected because the laser beam falls on the target and bounces back and then is detected by a photosensor.
But, what if it ...
1
vote
1answer
365 views
Does Bayer demosaicing from RGB-filter sensors work *because* the color filters are imprecise?
I have an ongoing friendly dispute with another member over on Photo Stack Exchange about the fundamentals of how RAW works, and I'm hoping you can settle it.
My understanding is that Bayer ...
1
vote
2answers
328 views
How does smartphone VR really work?
I know it doesn't sound like a physics question. But I couldn't find any satisfying answer on tech related forums, so I think that a pinch of scientific rigor is needed.
I've recently tried Google's ...
0
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1answer
53 views
Quadrature Modulation
I recently bought two Doppler Effect sensors HB100, but after reading more about the subject, I found out that these sensors can't distinguish if a target is moving towards or away from them.
I ...
2
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0answers
759 views
How Enthalpy sensor work - practically? [closed]
There are many links to enthalpy sensors used in industry, but have not found anything on the principle of their work. For example, thermometer mechanism could be a liquid (mercury) expanding ...
0
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2answers
74 views
Generate photons from radio waves
Photons can generate electricity via the photoelectric effect, but is it possible to go the other direction? Generate scintillations from radio waves?
The obvious answer would be to attach a light-...
1
vote
0answers
281 views
Building DIY Spectrometer Foreoptics: Slit to Circular FOV
I'm currently in the process of building a spectrometer, loosely following some of the instructions from the OpenLab DIY Spectrometer project, in order to further my understanding of sensor operation.
...
0
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0answers
22 views
Is spectroscopic analysis of flowing air sensitive to the amount of matter or the flux?
I would like to like to go deeper in understanding the analytical and physical behaviour of air quality analysers. AQ analysers are merely based on spectroscopy (absorbance, fluorescence, ...
0
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3answers
74 views
A logic question on binary variables
I recently purchased some nightlights with sensors. The sensor will make sure the nightlight will only be tuned on in a dark environment. Let's assume the sensor is binary, ON or OFF.
Here is the ...
1
vote
1answer
735 views
Orientation from acceleration?
I have an object that has a sensor attached on it. This sensor calculates the acceleration in all axis and angular acceleration in all axis(Keep the gravity force in mind). How can I get the Pitch, ...
1
vote
1answer
37 views
looking for a technique for conducting experiment [closed]
I have used a servomotor and a controlling circuit to produce oscillatory motion for an experiment that involves flapping of a tiny metal plate (~few mm) inside liquid. I could not be very successful ...
0
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1answer
1k views
Why should you be careful when you use a Hall effect probe to measure magnetic field?
Question: Why must you be careful with orientation when you use the hall effect probe to measure magnetic field?
Background: In a recent Physics 2 lab, we used a magnetic field sensor which ...
1
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0answers
26 views
What are the possible ways of detecting cell phones in some small space? [closed]
I guess i can somehow use the fact that cell phone is a source of electromagnetic waves. Considering the space of about 8m3 volume. What equipment setup can be used in order to count phones in a given ...
1
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1answer
284 views
How to sensor Jerk=$d^3{\bf r}/dt^3$, or higher derivatives (4th, 5th, 6th order) when applied in the equation of motion of a ballistic missile?
Given a 6th order differential equation of motion as usually used in ballastic missile dynamic models. What kind of sensors are usually used to measure Jerk, (or higher order derivatives in kinematics)...
