What is Detection: Definition and 337 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. R

    A A liquid crystal of Potassium-42 Chloride for directional neutrino detection

    I've been speculating on a method of neutrino detection that uses beta decay instead of scintillation for the detection of neutrinos and was curious about its viability. Potassium-42 can be synthesized by colliding Calcium 40 with protons. It has a half-life of 12.36 hours and decays into...
  2. P

    I How Do Positrons Reach Cloud Chambers Without Annihilating?

    I was researching on the Anderson cloud chamber that discovered the positron in 1932. I couldn't help but wonder, if positron annihilates upon contact with an electron, how was it able to get till the cloud chamber without annihilation? Shouldn't the 2 photons be the only thing observed in the...
  3. R

    Detect the presence of short-range UWB signals

    Ultra Wideband (UWB) RADAR systems discharge signals over a broad range of frequencies which is between 3GHz to 10GHz as compared to the conventional RADAR systems and remain extremely difficult to detect. an excerpt from page 2 of...
  4. B

    How does a Gas Chromatograph-Mass Spectrometer detect quantities?

    So I am working on theoretical project that challenges my group to detect and quantify a certain molecule in a sample. For the detection and quantification we have chosen to work with a gas chromatography-mass spectroscopy. However I am finding difficulties in how this device is able to detect...
  5. pinball1970

    I What are the implications of neutrino detection at the LHC?

    Article below https://phys.org/news/2023-08-neutrinos-cern-large-hadron-collider.amp Publication here. https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.031801
  6. Islam Nabil

    Thermal neutron detection using MCNP

    How can i detect the thermal neutron, E = 0.025 Ev, by MCNP using CUToff Or PHYS:N cards?
  7. D

    Why doesn't my collision detection between two Area2D objects in Godot 4 work?

    Hi everyone I'd like to detect collisions between a circle and a floor. I have set them up as follows: The script runs fine (it's just a circle falling towards the floor), but nothing happens when the two objects collide. Does anyone know what I've done wrong?Thanks
  8. F

    Automatic parking slots detection using Python

    TL;DR Summary: How to automatically detect the parking slots using Python? I have a Deep Machine Learning course and would like to do my course project about "Available Parking Slots Detection using Deep Machine Learning Based on Image Processing". My plan is to split the project into two...
  9. matthieu1973

    Efficient hit detection on a shot plate with piezo disc

    Hello to all, I wish to detect the hit of a airsoft pellet on a shot plate with an ESP32 board. to do this I have basically two options: Either, detect the signal as digital (hit / missed) or detect the signal as analog signal with a piezo disks. The analog signal will have more information...
  10. VVS2000

    I Wave packet experimental detection

    I know the wave function "collapses" when a measurement is made but still not satisfied with it
  11. Jamister

    A Homodyne detection quantum state tomography

    In balanced homodyne detection, it is claimed that one can do state tomography. I understand most of the derivation except one part. Here is a figure describing homodyne detection. the operator that is being measured is $$ R=N_{1}-N_{2}=a^{\dagger} b+b^{\dagger} a $$. taking the mode b to be...
  12. Oldman too

    I A new concept in Low Mass Dark Matter detection

    Summary:We propose a search for low mass dark matter particles through momentum recoils caused by their scattering from trapped, nanometer-scale objects. The Paper linked details a novel concept for detecting WIMPs. I hope to see more work performed on the idea in the future...
  13. B

    Image processing with Sobel Edge detection

    I am coding Sobel Edges detection in C#. I have a method that converts my image to grayscale. it adds the R G and B values and divides by 3. and replaces the R G and B value out with that same number. That seems to be working fine. Then I added a gaussian blur to it by using this...
  14. J

    Detection of spacecraft at large distances

    According to NASA the Space Shuttle required 12 GW to get it off the launch pad. So if a hypothetical rocket at the Second Lagrange Point (where the JWT is heading for right now) was producing the same amount of watts, all other things being equal, how far away in space could this output be...
  15. MathematicalPhysicist

    A Glueballs - definitive detection

    I was reading Muller's book on pQCD and I read on gluonium and it seems according to Wiki that its name changed to Glueballs. https://en.wikipedia.org/wiki/Glueball Why is it so hard to get a definitive detection of such a quantum state of gluons? Thanks!
  16. M

    I Single particle energy detection

    Hello! If I have a single ion traveling at a given energy (on the order of 10 keV), is there a way to read out its energy in real time with a single pass? Basically I was wondering if there is a device able to measure the current or magnetic field induced by the ion passing through it (while...
  17. fresh_42

    I How Will FASERν Transform Our Understanding of Neutrinos at High Energies?

    https://journals.aps.org/prd/pdf/10.1103/PhysRevD.104.L091101 And here is the pop science summary: https://www.sciencealert.com/for-the-first-time-neutrinos-may-have-been-detected-at-the-large-hadron-collider Which results can be expected?
  18. ergospherical

    I How does phase-sensitive detection eliminate noise?

    Trying to get my head around how to use phase-sensitive detection to eliminate noise. If the input (say, ##\cos{\omega_{\mathrm{in}} t}##) is modulated by a sinusoidal reference signal at ##\omega_0## with phase shift ##\phi##, fed through the amplifier (gain ##\kappa##) and then de-modulated by...
  19. Melbourne Guy

    B XENON1T and possible dark energy detection

    I can't see that this recent news has been discussed on PF, but the XENON1T dark matter detection collaboration is now suggesting that it has instead detected dark energy. They openly note speculation about what may have caused these results in the paper, but I'm more wondering if it adds weight...
  20. Dhananjay

    I Which machine learning model is best for detecting bottom quarks?

    which machine learning model to use to detect bottom quark, and on what basis the segregation should be done
  21. F

    How can I detect magnetic fields which are weaker than the Earth's?

    I don't have access to high power systems, or ultra precise detectors.(around 10V/ 1A) Can I detect small variations (frequencies ?) of magnetic field, while ignoring the noise caused by the Earth's magnetic field ? My goal is to measure the magnetic field through a line in order to trace it...
  22. QuentinChe

    Voltage detection in electrical cables

    Hello guys! I am a student who currently works on a project based on electrical detection and voltage measurement in electrical cables remotly. So in order to accomplish my work, I'm seeki ng for new ways to detect voltage. I already have some ideas such as using magnetic fields or measuring...
  23. .Scott

    Global Detection & Tracking any Aircraft Anywhere Anytime spots MH370

    The "Weak Signal Propagation Reporter" (WSPR) has been used in combination with other tracking methods by Richard Godfrey to refine the initial path of flight MH370 in March 2014. That flight disappeared in the Indian Ocean and two extensive underwater searches were unable to locate it. WSPR...
  24. J

    B Understanding Single Photon Detection in the Double-Slit Experiment

    When double-slit experimenters say an interference pattern is obtained even when only one photon at a time is fired at the slits, how do they know it was only one? The same when a photon detector is said to respond to single photons.
  25. J

    B Photon detection methods -- do they always involve displacing an electron?

    Am I right in thinking that all photon detection methods depend on a photon displacing an electron, that then displaces other electrons to give a detectable electric current pulse?
  26. C

    Calculating Count Rate for Neutron Beam Detection

    Finding the neutrons per second. Uncluttering the question: ##P = 6 \times 10^{7} J/s, E_{1} = 149.7 MeV/event, A = 10^{-4} m^{2}, R = 5 m ##. Number of events per second = ##\frac{P}{E_{1}}## = escaping neutrons per second Area of ##5m## sphere around reactor = ## 4 \pi R^{2} ## Fraction of...
  27. S

    Electrical 420-450MHz, High-Low state detection (without interference).

    Hello all, Im trying to come up with a simple method (and design) for detecting (mostly and foremost next to transmitting) a (continued) HIGH or LOW state through a specific frequency, most likely in the 420-450Mhz range. Without the possibility of interference. Preferably analog, at least on...
  28. M

    MATLAB Efficient Meniscus Line Detection in MATLAB - Simple and Automated Method

    Hi PF! Do any of you know a good way to detect the meniscus of the attached image (in MATLAB)? I have a very ghetto method, and would like something more automated. Thanks for your help!
  29. S

    Stargazing Possibility of detection of Earth approaching objects by gravity?

    Hey everyone, lately I read a german newspaper article about an Asteroid which passed Earth in a very small distance (asteroid 2020 QG, distance of closest approach was about 2950 km). Here is another link about this event written in English: Article about 2020 QG (Businessinsider.com). As far...
  30. A

    How do scientists use water Cerenkov detectors to detect neutrinos?

    Assuming that this sphere has a radius of 50kpc, I've converted to m (1.543e21) and plugged into the area equation for a total area of 2.992e43 m^2. From here I've talked myself into circles, and I honestly don't know where to go next. Any help or guidance would be greatly appreciated!
  31. M

    Engineering Superheterodyne Receiver with Phase Sensitive Detection Question

    Hi, Here is the figure 2 that the question referred to: How do I go about a question like this? I have made an attempt, but am not very confident with the method. Note, I have learned about/am aware of Fourier transforms. My attempt: So first I thought that the square wave will be at the...
  32. W

    I Detection of Neutral Currents

    In decay processes where no mixing between quark families is present, the mediator of the weak force is the neutral ##Z^0## boson. If that is the case, how is it experimentally possible to detect neutral currents in processes such as: $$\bar{\nu}_\mu + e \rightarrow \bar{\nu}_\mu + e$$ What...
  33. Z

    Prime Number Detection: Running Time of Algorithm

    Hi, I want to know if the algorithm to find prime number has running time O(sqrt(N)) or O(log^2N). log^2N is better than sqrt(N). Also for large values can it become a pseudo polynomial algorithm? Zulfi.
  34. N

    Suggestion for a gas discharge lamp

    There is a physics event being organized in my college for which I had planned to make a muon detector. I have the circuit ready which brings 240 volts ac mains source down to 80 volts dc supply. But now, I am facing a serious problem. I have been unable to find a neon glow lamp. Basically, mý...
  35. S

    Text color detection algorithm giving pixels of text

    I'm creating a type of image processing software and I have a need to get the color that best represents text once I have identified the pixels in a region of text. I've tried using simple strategies like "averaging" the pixels or taking the most common pixel, but these produces bad results An...
  36. Ranku

    I Heavier bosons and their function and detection

    Heavier bosons like ##W## or ##H## require high energy accelerator to be detected. Yet these bosons fulfill their function in the ambient energy of the universe. Why is it that their detection takes high energy environment but their function is possible in lower ambient energy?
  37. A

    I Why simultaneous detection of wave and particle nature is not possible

    We have been taught that the there is no experiment designed to detect wave and particle nature of light simultaneously. Also, that light propagates by the virtue of its wave nature and interacts by the virtue of its particle nature. let us take an electron beam passing through two slits...
  38. K

    Detect Single Electron: Fuji-Film & Kodak-Film?

    When I want to detect single electron(double-slits experiment), can I use usual photosensitive film(like Fuji-film, Kodak-film)? And, what specification I need?
  39. X

    B UV detection by fluorescent goggles

    I need to be able to detect and find shelter against the powerful UV radiation outdoors, since measuring devices are expensive and bulky, I decided to consider another method. Fluorescent materials are able to absorb UV light and re-emit as visible light. That gives me an idea to put fluorescent...
  40. M

    MHB Linear Codes : Error detection

    Hey! :o The code words of a linear code $C$ have the length $n=5$. Writing the code words into a matrix to get the linear independent ones, we get the following: \begin{equation*}\begin{pmatrix}0 & 0 & 0 & 0 & 0 \\ 0 & 1 & 1 & 0 & 1 \\ 1 & 0 & 1 & 1 & 1 \\ 1 & 1 & 0 & 1 &...
  41. Jardy

    Are there any automated methods for detecting soil nutrient levels?

    Good day, I would just like to ask if there are certain relationships of soil nutrients to other variables so that it can be easily detected and measured. I have searched the internet for a soil nutrient sensor but i couldn't find anything. If you have any other methods for soil nutrient...
  42. jim mcnamara

    Early moment detection that marks the start of massive tremor events

    Popular science: https://phys.org/news/2019-05-scientists-early-moment-megaquake.html https://advances.sciencemag.org/content/5/5/eaav2032 Image courtesy University of Oregon. 15 seconds into a massive event, there is data to support the concept of a warning of a coming massive event. Data...
  43. S

    Center surround detection explained?

    A while back I asked about human vision processing and if it is performed synchronously or asynchronously. One of the responses mentioned that the retina performs 'Center Surround Detection'. So I tried to google what this is but no relevant results came up. Is anyone able to explain what this...
  44. M

    Confused by envelope detection and windowing+overlapping

    Summary: Should both envelope detection and windowing+overlapping be used before FFT? Summary: Should both envelope detection and windowing+overlapping be used before FFT? Hi everyone! I'm somewhat a newbie to signal analysis, but I've also noticed that there seem to be many different...
  45. S

    B Does Entangled Particle Detection Prove the Spooky Action at a Distance?

    My question about quantum entaglement is: is a Quantum particle's spin [altered] into another spin position at the moment of detection or is it just a 'snapshot picture' of the spin at the moment of detection (without alteration)? It seems this is an important differentiation. If there is no...
  46. cianfa72

    I Can Gravitational Waves Affect Light Wavelengths?

    Hi, a simple question related to the gravitational wave detection. The net effect of gravitational wave is basically the stretching of the space including all the measurements tools (meter sticks just to illustrate the concept) that could be used to detect it. I am aware of laser...
  47. J

    RF pulse detection with Power Detectors

    How can I use power detectors for RF pulse detection? RF pulse has a symmetric Gaussian-like shape. Is the output of power detectors continuous line or point?
  48. TytoAlba95

    Can PCR detect chromosomal translocations in cancer?

    How is PCR able to detect chromosomal translocations causing cancer? I understand it is possible through FISH but how PCR?
  49. JasonGodbout

    I Detecting Gravitational Waves & Alcubierre Drive

    I saw a conference from a Ligo physicist she said they are detecting gravitation wave of collapsing star. I also read the Doppler effect is working on gravity due to limited speed (c). I want to know if it is possible to detect a big mass traveling close to the speed of light in ours frame of...