Questions tagged [sensor]

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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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31 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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29 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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109 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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13 views

Sensitivity required for underwater gravimetric detection

What is the order of magnitude of the sensitivity required for gravimetric detection of underwater moving objects with about neutral buoyancy, perhaps not homogeneous? I reason this includes ...
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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%).
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25 views

How to measure distance between object and mobile phone using camera? [duplicate]

I am trying to determine the distance between object being photographed and the mobile camera which is capturing the photo. The only device that is used is mobile phone, can we get depth or distance ...
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11 views

Calculating from sensor data

I have this kind of problem: The vibration of a milling machine's spindle is measured with an acceleration measurement system consisting of amplifier gain, filter, A/D converter and measurement ...
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1answer
31 views

Total output power of a laser

What is the interpretation of and the difference between the total power and total output power of a pulsed laser? How are these parameters measured and which type of detectors are the most ...
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34 views

Slots in optical incremental encoder

How can I calculate the amount of slots I need in my optical incremental encoder 's code wheel? For example, how many slots there should be, if I want to determine the position of screw which is ...
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30 views

Converting IMU measurements to that of a “virtual” IMU aligned with another frame on the same rigid body

Suppose that on a rigid body/object, we mount an IMU (inertial measurement unit) that measures the angular rate $\omega \in \mathbb{R}^3$ and the acceleration $a \in \mathbb{R}^3$ from the gyroscope ...
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56 views

How LHC sensors work? [closed]

newbie here. I am here because after working with Raspberry Pi sensors and Analog to Digital converters, and computer processors, I wondered how exactly do sensors in large scale physics experiments ...
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65 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 ...
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56 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 ...
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31 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 ...
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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 ...
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2answers
119 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 ...
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1answer
51 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 ...
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81 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 ...
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22 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 ...
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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 ...
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27 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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1answer
60 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 ...
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1answer
70 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 ...
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74 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 ...
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43 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 ...
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3answers
108 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 ...
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1k 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 ...
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2answers
5k 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 ...
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2answers
67 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 ...
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1answer
51 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 ...
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1answer
279 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 ...
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2answers
474 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 ...
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1answer
708 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 ...
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209 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 ...
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1answer
268 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 ...
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1answer
285 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, ...
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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 ...
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243 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 ...
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284 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 ...
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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 ...
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1answer
180 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 ...
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221 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 ...
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560 views

Ficticious forces influences what an accelerometer exactly measures?

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 ...
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72 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 ...
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483 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 ...
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336 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 ...
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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 ...
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967 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 ...
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76 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-...