What is Detection: Definition and 338 Discussions

In general, detection is the action of accessing information without specific cooperation from with the sender.
In the history of radio communications, the term "detector" was first used for a device that detected the simple presence or absence of a radio signal, since all communications were in Morse code. The term is still in use today to describe a component that extracts a particular signal from all of the electromagnetic waves present. Detection is usually based on the frequency of the carrier signal, as in the familiar frequencies of radio broadcasting, but it may also involve filtering a faint signal from noise, as in radio astronomy, or reconstructing a hidden signal, as in steganography.
In optoelectronics, "detection" means converting a received optical input to an electrical output. For example, the light signal received through an optical fiber is converted to an electrical signal in a detector such as a photodiode.
In steganography, attempts to detect hidden signals in suspected carrier material is referred to as steganalysis. Steganalysis has an interesting difference from most other types of detection, in that it can often only determine the probability that a hidden message exists; this is in contrast to the detection of signals which are simply encrypted, as the ciphertext can often be identified with certainty, even if it cannot be decoded.
In the military, detection refers to the special discipline of reconnaissance with the aim to recognize the presence of an object in a location or ambiance.
Finally, the art of detection, also known as following clues, is the work of a detective in attempting to reconstruct a sequence of events by identifying the relevant information in a situation.

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  1. M

    Question regarding pre-bigbang detection.

    Hi, I'm not a physicist although I've studied it to first year degree level in the UK many many years ago. I was just reading an article today on the BBC about a new image that's been captured of the visible universe. The following quote got me thinking and I wondered if your expert knowledge...
  2. M

    Hi.I am using a 3 axis accelerometer for motion detection. I can

    Hi. I am using a 3 axis accelerometer for motion detection. I can easily determine the tilt using simple triginometry but cannot determine the movement in a particular direction. For example the sensor is at 45 degrees to the floor so the x,z coordinates are x = 0.5, z = 0.5. So if I keep the...
  3. C

    Detection of Gamma Rays | Atomic Nucleus Decay

    Hi I'm studying decay of atomic nucleus. Alpha and beta rays are essentially particles and their path are easily traced. But high frequency gamma rays easily penetrate metal foils, and I wonder that how gamma rays are practically detected and measured in lab experiments? Is photo-electric...
  4. J

    Gravitational Wave Detection: Understanding Interferometers

    My understanding of how interferometers work is that they detect gravitational waves because they alter the distance between two mirrors as they pass through. They do this by using the wavelength of a laser beam passing through this space. However, shouldn't this always fail to detect anything...
  5. P

    Higgs field issues of detection?

    my view. The current theory of the higgs field is based on the higgs boson. Now a boson, in theory has to conform to the rules of super-fluidity or a Bose-Einstein Cond. I can confer because of this, All higgs bosons, would be interlocked as a field acting as one particle. I can say that since...
  6. F

    Thermal Imaging and Object Detection at Sea

    So my mind tends to wander, but I was thinking... since active/passive sonar is used to detect objects underwater, couldn't thermal imaging be used as well (in conjunction)? Isn't there any reason why we couldn't combine the two sensors into cooperatively working together to detect submarines...
  7. M

    Slit diffraction: time between emission and detection of photon

    For this question I am considering a slit diffraction experiment set up as follows: {Monochromatic source} ------> {Single slit} ------> {Diffraction grating with N slits} ------> {Screen with small movable detector} The monochromatic light source emits photons one at a time. The principal...
  8. K

    Peak detection using MATLAB (signal processing)

    I'm doing signal processing using MATLAB. But facing problem when doing Peak Detection. This is the signal that I used for the processing: This is what i wish to do: a) the horizontal line is the threshold point and b) the circle is the peak detection Can anyone help me...
  9. P

    How does the shock detection switch work in the ASLS15 model?

    As part of an engineering design project, I am using shock switches to measure accelerations of an object. As the name suggests they are just switches that turn on when a shock above a certain value is experienced. Does anyone know the details about how the switch contact is closed when it...
  10. M

    Automatic detection using wireless sensors

    I am designing a system that must automatically detect if a person is inside their office. The trick here now is that there are people going in and out and i just want to detect the owner of the office. Tracking them is useless since the average office sizes are not big, 5m width maximum so my...
  11. blainiac

    Help finding time between two frames for collision detection

    Hey everyone! I programmed a verlet physics engine that works great. I got to the collision detection and response and it's been frustrating to say the least. I've tried tons of different ways, but no cigar. The collisions themselves are between points and lines between points. These...
  12. T

    Can BSP Trees Be Used for Internal Collision Detection?

    Hi, I've got a problem with collision detection of which I am struggling to find a solution. In the simplest case, I would have a sphere whose movement would be constrained inside a closed arbitrarily-shaped object. I have been looking into BSP trees which split the shape into chunks...
  13. Ranku

    Detection of gravitational waves

    What is the state-of-the-art of detecting gravity waves. Are the instruments available now sufficiently sensitive to detect gravity waves? Have we identified 'low-hanging' sources from which gravity waves should have been detectable. Have we yet reached the point where doubts are arising as to...
  14. Ranku

    Detection of gravitational waves

    What is the state-of-the-art of detecting gravity waves. Are the instruments available now sufficiently sensitive to detect gravity waves? Have we identified 'low-hanging' sources from whom gravity waves should have been detectable. Have we yet reached that point where serious questions are...
  15. T

    What exactly is meant by Fourier techniques for edge detection?

    What exactly is meant by "Fourier techniques" for edge detection? I'm trying to work on an edge detection assignment for a Fourier Analysis class. I've nailed every bit of it up to this point, but now the assignment is wanting me to do edge detection via "Fourier techniques." No amount of...
  16. D

    Detection of string vibrations using home equipment

    Hi I have a problem in detecting whether string is vibrating or not. I'm going to conduct experiment which will investigate impact of different factors on time of decaying of guitar's string oscillations but I have no idea how to measure when oscillations stopped. Acoustic method doesn't work...
  17. D

    Detection of a non-interacting particle

    In another thread, which I do not want to derail, I claimed that a free, non-interacting particle is not physical and that it cannot be detected or observed. It was pointed out to me that apparently I'm the only one on here who doubts about the possibility of detecting a non-interacting...
  18. UseAsDirected

    Expanding universe and light detection

    Sorry if this question has been reproduced elsewhere. If the universe expands greater than the speed of light, c, will a light ray from a distant object never reach us? Lawrence Krauss gave a nice presentation and commented about this, but this has thrown my nose out of sorts because I think...
  19. W

    Detection Methods: Heterodyne, Differential, Normal & Homodyne

    Hi, Just a query... what is the differences between this types of detection and their usage? a) heterodyne b) differential c) normal d) homodyne?
  20. J

    Detecting Shorted MOSFETs in Output Stage

    Hey Everyone, The title of this thread may be a bit ambiguous but what I am wondering is if there is a way to determine if a MOSFET in an output stage has shorted. The scenario I want to catch is the case where the FET drain is exposed to too much voltage (from a collapsing spike or some...
  21. F

    Triggering a Camera for Train Detection: Ideas and Resources

    What do you guys think would be the best way to trip a camera so that it goes off only for when a train is passing through it? Sorry I can't get anymore specific than that. I was thinking laser tripping device but was wondering if there is anything out there that maybe used that ya'll might...
  22. P

    Supernova explosions element detection.

    Hey ppl i wanted to know that wat is the name of the method with which astrosphysicists are able to detect the elements present in supernovae.for eg they say type 2 suprnva is mainly hydrogen containing. Is it by spectroscopy if yes which one? pleasez temme soon
  23. P

    Does Beam Interference Depend on Longitudinal Distance Post-Beamsplitter?

    If you have 2 laser beams, A and B, at right angle with each other, that you send towards a beamsplitter (BS), such that you get 2 output beams from the BS, one being the sum of the reflected part of A and transmitted part of B, and the other the transmitted part of A and reflected part of B...
  24. J

    Detection of longitudinal and shear acoustic waves in solids

    I want to be able to differentiate between longitudinal(P) and Shear(S) waves in solids. Using one Acoustic emission (AE) senor placed 2 to 20 cm form a AE source e.g. a stress induced crack or pencil lead test, how can one detect both the P and S waves and determine what part of the receive...
  25. M

    Can Blade Breakage Be Detected without External Sensors?

    Dear all, The idea is to detect break down of a group of blades inside a pipe. It’s very difficult to install any type of sensors inside a pipe without having them damaged, given that the pipe is an air vacuum suction system. How about concentrating on the physical properties of the blade...
  26. F

    Probability of Beta Particle Detection from Uniformly Covered Surface

    We have a surface that is 10 cm x 10 cm. That surface is uniformly covered with a radioactive material. When radioactive material decays, it has a equal probability of emitting radioactive particles, in this case beta particles, in any direction (360 degrees). We have a detector that...
  27. J

    Can a contour integral be used to detect complex polygon deformations?

    Hi, I am working on a simulation code that simulates the deformation of sand grains in 2D. The sand grains are modeled as simple polygons. However, during the simulation the grains can deform to create non-convex vertices. Further more, when deformation becomes extreme, there is a possibility...
  28. G

    Does the Detection of Gluons Provide Strong Evidence for Their Existence?

    Hi to everyone: Does anybody of you know when was the gluon detected?, and how do you detect gluons? I hope you can answer Thank you
  29. B

    Lorentz contraction and simultaneous detection of the ends of the moving rod?

    It is known that with the formula that accounts for the time dilation effect in hand we can derive directly the formula that accounts for the length contraction effect: L0/Dt=L/(Dt)0 (1) where L0 and (Dt)0 are proper length and proper time intervals, L and Dt...
  30. U

    How to design rupture disc leak detection sensor element?

    I am to design a sensor element that can detect a leakage through a thin metal disc (rupture disc) in a pipeline. Ideally, the metal disc closes the pipeline at the upstreaming side with certain pressure. Its downstream can be either open to atmosphere or close. When a higher pressure occurs...
  31. M

    Coincidence and Single Rate detection in Quantum Eraser experiments

    I am having difficulty understanding why the single rate of detection (as opposed to the coincidence rate) is unaffected during Quantum Eraser experiments. I'm looking at the great Kwait, Steinberg and Chiao paper: 'Observation of a "quantum eraser": A revival of coherence in a two-photon...
  32. H

    Nuclear Detection Tech: Airborne Sensors for NYC?

    So I posted this in a few other forums, but I thought that this would be a good place to get even more feedback. Sorry, mods. Does anyone here know what developments are being made in nuclear detection technology? Is there anything like, say, an airborne sensor that can detect the tiniest...
  33. U

    Interstellar TV: Calculating Detection Range

    I am just "trying" to watch interstellar TV... The detection range in lightyears is R = \sqrt{\frac{\text{EIRP}\cdot A_{e}_{r}\cdot\text{twc}}{4\pi\cdot\text{SNR}\cdot B_{r}\cdot k_{B}\cdot T_{sys}}}\cdot\frac{1\,\text{ly}}{9454254955488000\,\text{m}}, where \text{EIRP} = P_{t}G_{t}...
  34. F

    How is the Bethe-Bloch formula used in gamma-ray photon detection?

    can some one give me a link or an article or his argument which Explain how the Bethe-Bloch formula is used to determine the energy of a gamma-ray photon stopped in a spark-chamber detector. thanks
  35. A

    Engineering How to improve sensivity of detection circuit(Photodiode)?

    How to improve sensivity of detection circuit(Photodiode)??
  36. hxtasy

    Water detection stickers on cell phones?

    does anyone know the chemical process involved with these? pretty much a white sticker and when it gets wet it turns red.
  37. L

    Momentum-space detection of an Electron (EWP)

    [SOLVED] Momentum-space detection of an Electron (EWP) I know there have been plenty of questions about electrons, momentum, and wave packets recently - but my question is distinct (and comes with a picture!). Question: If you ionize an atom and detect the resulting free electron wave packet...
  38. B

    Polarization, then detection: collapse when?

    In the book 'Quantum Physics', Alastair Rae uses polarized photons and photon detectors to describe many effects observed in quantum physics. In his typical setup, photons are passed through a polarizer and exit it through two different channels depending on the polarization \phi or...
  39. N

    Impact Detection: Find an IC & Shock Sensor Solution

    Hello. I'm having the hardest time finding a product (preferably an IC) that can detect shock. Like if you dropped your phone on the ground it would detect an impact with the floor, with some kind of threshold to ignore minor bumps and thumps. I did find some toshiba ICs called "shock detector...
  40. B

    Higgs Particles: Big Mass, Bigger Detection Challenge?

    They say Higgs particles are so hard to detect because their mass is so big. But when their mass is so big, wouldn't that make them easier to detect?
  41. E

    Threads of Execution: How to Look at Them (Fast Detection of a Possible Problem)

    Hi Ho! Is there a better way of looking at more than one threads of execution besides enumerating all of the possible paths so that a person can quickly determine whether there will be a problem or not? When I face a question of determining whether two threads of execution will have a...
  42. K

    Simple circle circle collision detection

    hi all, I am testing the collision detection between two circle using classic the distance < sumRadius. now i need help to detect the penetration of circles and to resolve the penetration before collision reaction
  43. C

    Looking for someone who knows pulse induction/metal detection theory

    Hi there I'm looking for anyone who has the knowledge or experience that can help me develop a pulse induction gold metal detector. I have the fabrication resources but need someone who understand metal detection/circuit board technology. Please Email with experience.
  44. H

    Cmput: 2D parity error detection scheme

    Question Details: The following blocks have been encoded using the two-dimensional parity error detection scheme. That is, the rows have been encoded using odd parity and the last row holds the parity bits of the columns which have also been encoded using odd parity. There are two possible...
  45. C

    Higgs boson detection is it possible as of 2008

    The Higgs boson introduced by P. Higgs (insert --> the spontaneous symmetry breaking with the gauge theories was also constructed by Robert Brout & Francois Englert) one question I do have is on the dynamics involved dealing with this concept - is it truly possible to detect the process by decay...
  46. Garth

    Direct Detection of Cold Dark Matter

    An interesting review paper of the search for DM particle(s): Direct Detection of Cold Dark Matter. The search continues. Garth
  47. E

    Uncovering the Mystery of Neutrino Particles: How Scientists Detect Them

    Hi guyz my teacher recently asked me..how did we actually discover(or how do we find ) a neutrino particle...remember a neutrino particle has 0 mass and 0 charge.. well my guess to this was using rest mass theory...which says tat..some particles wen givin velocity above the speed of...
  48. O

    Digital Electronics Project - Sound detection

    Greetings all, I thought I'd post my idea and plan for my digital electronics project here to see if I can get any tips or meet people who may have some expertise on this subject... The basic idea is a 'lock' that is opened by the correct series of input notes. Using a PIC, what I'm...
  49. R

    Detect Low Currents in Nano/Pico Amperes

    Hello everyone. I am looking for a practical method to detect very small currents in nano or pico amperes. Are there galvanotmeters or devices capable of doing that? Thanks a lot.
  50. benzun_1999

    Designing a Small Location Detection System with RFID Tags

    hi, i need help... i am planing to design a small location detection system within a room using RFID tags or some resonace technique. Each object must have a unique identification code. I intend to place 4 detectors like Satellites to determine the exact position of the object... I need...
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