What is Noise: Definition and 501 Discussions

Noise is unwanted sound considered unpleasant, loud or disruptive to hearing. From a physics standpoint, noise is indistinguishable from desired sound, as both are vibrations through a medium, such as air or water. The difference arises when the brain receives and perceives a sound.Acoustic noise is any sound in the acoustic domain, either deliberate (e.g., music or speech) or unintended. In contrast, noise in electronics may not be audible to the human ear and may require instruments for detection.In audio engineering, noise can refer to the unwanted residual electronic noise signal that gives rise to acoustic noise heard as a hiss. This signal noise is commonly measured using A-weighting or ITU-R 468 weighting.In experimental sciences, noise can refer to any random fluctuations of data that hinders perception of a signal.

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  1. Nikhil N

    How to make a hardware setup for monitoring BER of modbus

    I have to devices in communication with modbus protocol. Master is PC and slave is compressor(100ft line,RS485 standard, modbus RTU protocol). I have to build a setup which will show how much the error in communication. I am coupling some white noise to the line and some burst signals too. I...
  2. uzi kiko

    A Reducing Gaussian Noise in Antenna Impedance Measurements

    Hi I am measuring the impedance of an operating antenna over time. Assuming the environment is not changing and the antenna temperature remain constant (No thermal drift) I am receiving the impedance value and additional noise that I want to model as Gaussian noise. So my simple model is: Y = X...
  3. M

    Noise Calculation with the Equipartition Theorem Method?

    Anybody know how calculate the noise with equipartition theorem method? For a simple RC one order filter. The noise charge across the capacitor is Q. we have 1/2*k*T=1/2*C*(Q/C)^2 For a more complicated network as below. Can you help me on how to calculate the total noise charge or voltage...
  4. M

    How Do I Add Voltage Noise in LTspice and Analyze Its Response?

    Hello, I try to add a voltage noise using an arbitrary voltage source set as V=white(1). Since I couldn't find any info about that parameter for the white() function I decided to do a .noise analysis to see how it responds to different values of that parameter. Except I can't get any kind of my...
  5. L

    Electrostatic/electromagnetic noise and conductive area

    I play electric guitar, and electromagnetic noise is a big concern for us. There are two types of noise, those that arrive as magnetic fields and those that arrive as electrical fields. This web page is a resource from which I've derived this understanding...
  6. Nikhil N

    Noise due to chattering of relay

    I need to know how to couple noise due to chattering of relay? I have seen the below method to couple. But I want more detailed circuit to do this. Please help me. Also I want to know where the tremendous amount of EMI can be seen ? Is it across the coil of relay?
  7. Nikhil N

    Current transformer for coupling noise into a cable

    I want to couple white noise to a communication cable. I am using a 50/5A CT. My idea is to connect the noise in the secondary and to couple that noise into the cable. I want to know will my idea work? Does the CT what I am using will be suitable?
  8. N

    How can I cancel out vibration and noise coming from my upstairs neighbors?

    Hello gentlemen! So I have a situation. Concrete floor (ceiling actually) slabs like these has many cylindrical spaces in it. And noisy neighbors on top! The slab receives shocks / impacts and human shouts. First I found Tuned Mass Damper. It is good for continuous vibration but not for first...
  9. baby_1

    Some questions about Noise and Power spectral Density

    Hello I've got confused about some features of noise. 1)Can use noise a generator? Well , if we have a noisy resistor and Ideal resistor why can't we use noise voltage according to noise voltage Vn=\sqrt(4KTBR) 2)why we divide power spectral density to RL( load) when we find power at RL?(it is...
  10. M

    Electronic Noise General Questions - Laboratory Setting

    Hello all, I'm an undergraduate at a large research university in Massachusetts working in a lab where my group contributes to the Muon g-2 experiment at Fermilab in chicago. Essentially what I'm working on is optimizing an optical rotation (Faraday) magnetometer system for use in magnetic...
  11. Borek

    How can I reduce noise induced in a wire for my Nixie clock?

    Not sure if I posted it here or elsewhere. I made a Nixie clock controlled with an Arduino. To make it possible to set the clock I have added a button connected with a wire. Pressed button generates an interrupt which I use to "round" the clock up or down to a full minute. The button has a...
  12. hackhard

    Optimizing Light Controlled Bot Circuit for Improved Performance

    Im working on a project which cycles through stop,forward, back,left, right modes of a bot using light pulses as input . light source is laser pointer , room is dark the circuit is not mounted on the bot the circuit - light pulse -> ldr-> bc337transistor ->7404 NOT -> 4017 decade counter ->7483...
  13. Nantes

    I Fans with 3 blades vs. 6 blades (noise, efficiency)?

    I'm Brazilian, and until a few years ago most commercial electric fans sold in the country looked like this: But then one company started making them with 6 blades, claiming it had better wind output and made less noise than the 3-bladed fans (they didn't directly made this claim; it was...
  14. J

    Noise isolation headphone recommendations?

    I am looking for some noise isolating headphones for my younger daughter to use when my older daughter is practicing her french horn. It is one loud instrument! I wouldn't expect active noise cancelling headphones to work since I have a hard time believing they can respond quickly as a horn...
  15. I

    A Shot Noise in Double-Quantum dots

    Hello all, So I am working on a problem where I need to characterize the shot noise in double quantum dots. My professor suggested to me that we can estimate the tunnel times from shot noise calculations. Can anyone give me any insight into this? Moreover, can anyone provide me any numerical...
  16. D

    What is the correct formula for calculating noise level in decibels?

    Homework Statement When the distance to a sound source is doubled, the noise level will be halved. Yes or no? Homework Equations L = 10 lg(I/10-12) or L = 10 lg(I/l0) The Attempt at a Solution my book used the first formula in another question and it used the second one in this problem. I...
  17. G

    Op-amp circuits and noise at high frequency/low amplitude

    Hi everyone. I am tasked with amplifying an input voltage of around 1nA at anywhere between 10,000kHz to 1MHz to a sufficient amount. We've been using op-amps in multiple stages in series to amplify the signal. At our disposal we have a function generator, oscilloscope, breadboard and...
  18. G

    Op-amps, noise and high frequency/low current input signal

    Hello everyone, In my lab class we've been given task of using op-amps to amplify a current of 1nA and frequency of order of madnitude 1MHz to a discernable level. We've been given breadboards, a selection of different op amps, resistors, an oscilloscope etc to achieve this task. We've made...
  19. S

    What is causing the faint clattering noise in my desktop computer?

    I build new desktop computers every few years and I like quiet machines. Hard drives (to my ears) are noisy, so my last four machines have used a combination of solid state drives and spinning lap top drives. When I use any of these machines I hear faint sounds that I've always interpreted as...
  20. Q

    A Can Noise Cancelling Theory Be Used to Send Secret Messages?

    Hi, I had kind of a cool idea and was wondering if someone would try and refute it or tell me if it would be possible. So let's say you have three people sitting three metres apart, and you need to deliver a message via sound to person B, who is the person in the middle. Would it be possible...
  21. E

    I Horizontal Noise Stripes in an Image

    What are the possible causes of the horizontal noise stripes in this image: http://dsp.stackexchange.com/questions/20061/removing-periodic-noise-from-image-using-fourier-transform I'm currently studying on these kinds of noise, and how to eliminate them. Can these be caused by diffraction...
  22. wolram

    B Does LIGO detect back ground noise

    I suspect it has a very noisy pick up from back ground gravitational radiation, what source is the most likely candidate for this back ground radiation?
  23. Twigg

    I Effect of a Moving Average on Gaussian Noise

    Hi all, I think there is a really obvious answer to this, but I just don't see it yet. Suppose you had N data sets that all measured the same quantity as a function of time. Each data set shows the same signal plus a random noise component which is normally distributed about the signal with a...
  24. kolleamm

    Why are gears made from bulk metallic glass ideal for precision robotics?

    In an attempt to find ways to reduce the noise generated by my robot, I'm trying to understand why the servo motors themselves make noise. On the web I've read their noise has to do with the gears they have. Even when a servo is not on and you turn it, it makes noise due to the gears. Can...
  25. W

    Unwanted noise in oscilloscope diaplay

    Hi I'm a beginner on using an oscilloscope and I'm sorry if my question may be repeated in other posts. I was working on a circuit with the following materials: (1) an Al plate (5mm thick) (2) a disk-shaped piezo transducer with special electrodes (product...
  26. D

    A Understanding Function Generator Noise for Calibrating Noise Measurements

    I want to calibrate my measurement setup for noise measurements. I have taken some measurements but I need to confirm that my measurement correlates with the Johnson noise theory. To do this, I have tried measuring resistors but I seem not to get the right results. My supervisor then...
  27. Planobilly

    Resistor noise reduction questions

    Hi Guys, I am looking for a high level overview concerning resistor noise and how to reduce it. I have read the following general statements. Carbon comp resistors are rated at 0 db. I read this somewhere. Vishay metal film resistors MIL-R-10506 are rated at -40 db...
  28. H

    B What is the source of this intriguing natural noise diagram?

    I am trying to find the source of this diagram which came out of some old notes (not mine) I found uploaded on the web. the referencing is not clear. it seems a great diagram and I would like to find a similar one like it (or better graphics) if not the original, and some explanatory text. I...
  29. kolleamm

    Reducing servo motor jitter noise

    I have a digital servo that makes a lot of jittering noise. The motor itself works great, however when you set it to a certain position while applying a force it will make a jittering sound as it tries to find the optimal position, which is pretty common for digital servos to do. My question is...
  30. K

    Complete Noise Analysis: to find the minimum detectable signal

    Problem Statement: my aim is to digitalize a 10ns narrow pulse coming from a photo diode with current ranging from 10nA-70mA, as its impossible to cover this dynamic range of >60dB using a single TIA i have an option of separating it to two channels as below using two diodes ofcourse Lowest...
  31. davenn

    Stargazing Deep Space Imaging and stacking images for less noise

    hi guys Today I would like to show the advantages of stacking a set of exposures over just a single shot There are various ways to stack individual exposures. A number of programs are available ranging from free to quite expensive ... several 100 US$ free = DSS - Deep Sky Stacker...
  32. B

    Signal to noise ratio in a CT scanner

    Homework Statement If the relative noise (noise divided by signal) in a region of a CT slice is measured to be N what would be the value if the tube current was halved, the pitch increased from 0.9 to 1.2, the rotation time increased from 0.75s to 1s and the slice width increased from 1mm to...
  33. P

    Efficacy of Balanced XLR Cables for Noise Reduction

    When attempting to find an answer to the "quality" of sound one attains from various audio cables, most of the research leads to the very subjective answers of audio/sound engineers. I was hoping to gain some insight from a physics/engineering perspective. I'm curious if an expensive or...
  34. U

    How does a spectrum analyzer measure Noise Spectral Density

    Hi, I'm a noob when is comes to these kinds of measurements on a spectrum analyzer. Take for example two LDOs: 1. http://www.analog.com/media/en/technical-documentation/data-sheets/ADM7154.pdf 2. http://www.ti.com/lit/ds/symlink/lp5907.pdf (see figure 17) They claim...
  35. N

    Physics of noise picked up by a radio when home lights are switched off

    I would like to get an, if possible, detailed analysis of the phenomenon by which you hear a noise in your radio speakers when the home lights are switched off. It probably has to do with a wave packet emitted due to switching off the lights, which is picked up by the antenna of a conventional...
  36. T

    I Calculating noise in a data sample - what region to use

    I have a data set of number of counts vs position where counts were detected. I want to find the noise in the sample. Am I right to think that by 'noise' the requestor wants to know the standard error (SE = stdev/sqrt(N)) where N is the sum of x-axis points. Also if the above it true then is the...
  37. J

    Subharmonic noise in DC-AC H-bridge Inverter

    I have a design for a DC-AC full H-bridge inverter implemented with IGBTs that is functioning quite well, but there is one problem that I am having trouble solving. I am seeing spikes in the FFT of the output noise floor that appear to be subharmonics of the PWM frequency. I am measuring the...
  38. M

    Recording gravity waves over the noise floor

    I'm curious as to how the gravity waves were recorded given how small the amplitude of the wave was/is. Was it not below the thermal noise floor? Were noise removal techniques used, etc? Also, what kind of sampling rate/bit depth was used? Thanks
  39. K

    Automotive Why is an FFT done after a noise signal is captured?

    Presently there is a gear whine noise issue in a vehicle transmission. Our NVH team captured the noise signal using a microphone and then did an FFT of the signal and gave us a frequency plot. What exactly can I take out of it? Can I assume every harmonic belongs to a noise generated by a gear...
  40. A

    Seed, Noise and undoing pseudorandomization

    Okay, title doesn't give a lot of information so please bear with me here. Forget the why, I just need to figure out how. I would like, given an array of floats(such as those that would be generated by perlin noise) to be able to extract what seed would be used to generate said set of numbers...
  41. C

    Signal to noise ratio and uncertainty in magnitude

    1. The problem statement, all variables and given/known dat Show that if you have a signal f and noise σf for a stellar flux measurement, then the uncertainty on the observed magnitude is given by σm = 1.0875 x σf / f Homework Equations (you should use the fact that when ε<<1 then log(1±ε) ≈...
  42. B

    TV antenna amplifier noise calculation

    Homework Statement Hello everyone. A 4-way TV antenna amplifier has the following specifications: Bandwidth = 40-862Mhz Gain = 20dB Noise figure = 6 dB Max output = 85dBuV Input impedance = output impedance = 75 ohm Question 1: Calculate the required voltage on the input of the amplifier to...
  43. caters

    Most of the noise coming from the lioness?

    I notice when lions mate that it is the lioness that makes the most noise. Yes the male does make a deep growl when he grabs the lioness by the neck but the lioness makes a constant high pitched sound that sometimes sounds like a meow. A good example starts at 41:38 in the Lion Brotherhood...
  44. B

    Question about Nyquist frequency and noise

    Homework Statement A time series is sampled at 250 Hz. What is the sampling interval and Nyquist frequency of the original signal, before digitising was contaminated with noise at about 300 Hz. At what frequency would this noise appear in the spectrum of the digitised sequence ? Repeat the...
  45. C

    Effect of noise cancelling audio equipment

    Noise cancelling earbuds/headphones differ from noise isolating earbuds/headphones. Noise isolation just keeps the sound out, whereas noise cancellation actively produces sound in order to "cancel" noise.I understand how this works technologically, however do these sound waves cancel out so that...
  46. R

    Meaning of having powerful signal near to 0Hz

    Hello I computed, with python scipy.rfft, the Fourier transform of signal coming from an accelerometer. I don't understood what this is the meaning of having a powerful signal near to 0 Hz ?
  47. T

    Estimate noise improvement as a funtion of sampling rate

    Hi all, I would like to estimate from my experimental data what would be the noise of the signal if I could sample at a higher rate. It is possible to do that? Do you have any references to good books that explain this topic? Thank you!
  48. R

    Simulating noise with Yuler and Burg

    Hi After removing high frequency white noise in my INS sensor, I want to simulate low frequency noise with Burg or Yuler. I used some functions in python to analyse the recorded data and to get parameters to use. But the the problem is the sequences generated diverge (and take very big...
  49. R

    Noise modeling with Markov modeling

    Hi I'm using accelerometer & horizontal gyroscope in order to replace GPS. Now, I'want to model the noise with first order markov process, to use it in kalman filter. I recorded measurement on all axes and computed auto-correlation. This picture represents auto-correlation on one of axes...
  50. E

    Separate noise from signal if I know the noise

    Hi all! I have this problem: I have some data that come from a negative binomial distribution with unknown parameters and some additive noise with gaussian distribution of known parameters. What is the best way to remove the noise from the distribution of the data? I tried bot a very basic mean...
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