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. cpscdave

    How to guage noise of 3 wire serial line (RS485)

    How should I gauge noise on a RS485 line? (2 equal and opposite data lines and a shield line) I tried connecting a Oscope. Persumably however the same noise is appearing on all 3 lines. So if I attach my oscope probe to 1 of the data lines, and the ground to shield all the noise will be...
  2. M

    Maximum Source Resistance for Optimal ADC Performance

    Homework Statement A simplified model of ADC noise refers the noise to a noisy source resistance Rn while assuming the rest of the signal path to be noiseless. Figure 3 represents a particular 18-bit ADC that has a 10 V input voltage range. The ADC has a bandwidth of 1 MHz. Calculate the...
  3. Kyle Burris

    Mechanical noise - A/C and radon fan standing wave hum

    Hello, I am moving into a new house, remodeling, etc. & am installing a new A/C compressor and radon fan. Being that low frequency noise highly bothers me & affects my insomnia quite a bit, I am trying to look at all considerations regarding acoustics, mechanical sound propagation properties...
  4. SSGD

    How Can Vibration Damping Materials Reduce Machine Noise?

    I am trying to reduce the noise created from a machine that makes contact (impact) with a thin plate. I just don't have anyone to bounce ideas off of. I can change the support geometry to whatever I want as long as it will with stand a static load and the impact. I can handle this, but the...
  5. D

    Why does lowering the slew rate lower the electrical noise?

    From my research I am showing that if an input signal becomes too slow (ie: a low slew rate) then the noise can cause multiple state changes. But I am being told that if the slew rate is low then it will get rid of unwanted noise. I read my results from this: (I lost the link but I did copy...
  6. baby_1

    Best Books to understand Noise

    Hello I have many problems to understand Noise , Noise figure , Shot noise and etc and I have to know completely about calculate Noise to calculate BJT , Mosfet and Block diagram amplifier. I will appreciate that you suggest a good book about Noise with simple steps Thanks
  7. J

    Noise Issues with closed loop accelerometers

    Hi, Can anybody explain to me what the major noise issues are with mems closed loop accelerometers
  8. H

    Can Soundproof Rugs Solve My Upstairs Neighbor's Noise Complaints?

    I live in a second floor apartment and I am having trouble with floor noise. I just moved in this week and the guy below me has already yelled from his room a few times to "Go to bed, son of a bit**". Well, the problem with that is 1) I was only walking through my bedroom, 2) it was 8 at night...
  9. L

    How do environmental conditions affect the way we hear traffic noise?

    I'm curious as to why I can hear traffic noise sometimes and not others. The busy hwy is about a mile away across a field. Sometimes it sounds like it is at my door but other times I can't hear it but still see a lot of traffic. How does environmental conditions (temp, no wind, etc) affect the...
  10. grandpa2390

    Popping noise from speakers when I turn the fan off

    I just noticed this and it is crazy. I have a little speaker that I plug into my computer. it is being charged by the usb port. I got up and turned off the fan in my room and I heard a popping noise. It worried me a bit, so I turned the fan back on (no noise), then I turned it off and I heard...
  11. Jordaniel

    Seeing UV & IF Light: Exploring My Perception

    When I observe the UV light emitted, I can literally see the millions of photons appear and die within milliseconds, but nobody else around me can. When I observe IF light sources and transmitters in low light, it is the same characteristic, except there only appears to be to photon sources, and...
  12. P

    Microwave Engineering -- Noise figure of a cascade

    Hi, I am taking a course in Microwave Engineering and we were given the following problem to solve An amplifier with a gain of 12 dB, a bandwidth of 150 MHz, and a noise figure of 4 dB feeds a receiver with a noise temperature of 900 K. Find the noise figure of the overall system. Need I to use...
  13. T

    Improving Frequency Resolution with Window Functions in FFT Calculations

    Okay I have a question involving calculating the FFT of a signal from a sensor. I have simulated many different scenarios in MATLAB of various noise characteristics involving the signal. I want to take the FFT of a noisy signal. As long as my expected input signal has a higher amplitude than...
  14. K

    Why "rate random walk" exists on gyroscpe ?

    hi I read an article about stochastic error modeling, and I didn't understand this extract about error sources : how can the "rate random walk" be present, while the gyroscope directly angular rate ? the article's title is : "Stochastic Modeling of MEMS Inertial Sensors " by Petko Petkov and...
  15. S

    Problem with spice -- Noise analysis error

    I am using a circuit attached as image and the AC analysis is working perfectly. Output is at the netlist of the AD8139 pin 5. The noise analysis showing the error : *Analysis directives: .AC DEC 10 10 1g .NOISE V19 V[N08184] 30 -------$ ERROR(ORPSIM-16291): Must be independent source (I or V)...
  16. Runei

    Available Noise Power and Amplifiers

    Hello there, I'm working with the textbook by Wim van Etten, "Introduction to Random Signals and Noise". And right now I'm preparing for an exam in a stochastic processes course. I have a question regarding some noise calculations, that I just can't wrap my head around. I hope someone will be...
  17. B

    MHB Noise signal in freq domain

    Hi Folks, I have an article which explains the modulation of 2 signals given by X_1(f) e^{-j 2 \pi f t_i} and X_2(f) e^{-j 2 \pi f t_i} The only difference between the 2 signals is a time delay, however i don't see a phase difference in either expression It states the convolution of these...
  18. X

    Optical Noise Photons: Calculate Sun's Ambient Light for Detector Simulation

    I need this information for a simulation I am working on that involves optical photon detectors. Specifically, I need a rough figure for how many photons a photon detector would register per second if I were to place it in ambient light from the sun. I realize that this number depends on the...
  19. M

    Differential Equation with Noise term

    Homework Statement (\partial_t - A\nabla^2 + B)f(x) = \eta(x, t) So I have a homogeneous linear differential equation except for an added noise term ##\eta(t) ##. The noise is uncorrelated between times and has a Gaussian distribution with zero mean. That is we have Gaussian white noise...
  20. M

    Noise efficiency of fan designs

    In particular I am wondering about compressor blades, but it's an interesting question to pose for household type fans as well. We can imagine "waterwheel" type schemes, and also the more traditional schemes where the axis of rotation is parallel to the flow. Which produces more noise per...
  21. T

    Parking garage jet fan - too much noise?

    I am to choose a certain type of jet fan in a parking garage. Looking at a spesific one, what I'm having a hard time considering is the noise it generates - 78 dB (A) at 3 m - and whether it would within acceptable limits? This is a fan that you would pass underneath walking to or from your car...
  22. M

    Mains Electric Noise Frequency in UK

    What is the frequency of mains electric noise in the uk?
  23. CassiopeiaA

    RMS value & noise measurements

    I am confused about very fundamental question. Why does the rms value of number of electrons collected from a signal(like in photoconductor) gives you the noise in that signal.
  24. J

    Noise voltage from t-network feedback in opamp circuit

    I'm struggling to compute the noise voltage due to the thermal noise on the resistors of an op-amp circuit, configured as a t-network. If it were a single feedback resistor, the noise voltage referenced to the output (RTO)would be given by sqrt(4KTRB). I'm not sure how to combine them...
  25. J

    Current noise density from Ibias on op amp datasheet

    it is my understanding that the input referred noise current (density) can be obtained from Ibias via inoise=sqrt(2*q*Ibias), where q=1.6e-19. on op-amp datasheets, both Ibias and the input referred noise current are both specified. Yet, the value typically shown for the noise current...
  26. davidbenari

    Swooshing noise as car drives near obstacles

    As you drive with your windows open you can hear a sound due to some continuous stream of air that is hitting your face, or whatever. But why is it then, that when you drive past by some obstacle, like a tree, you hear a swooshing noise? What is causing this?
  27. S

    Guess propulsion type by its noise

    Could you define what propulsion type this one vehicle uses by noise it makes?
  28. R

    Can a throat microphone effectively filter out engine noise from human voice?

    I am looking to filter the human voice from enviornmental noise (engine/machinery noise). I was doing some digging and the human voice is between 300 and 10,000 Hz, unfortunatly some of the engine noise is in the same frequency. I could build a bandpass filter and at least eliminate some of...
  29. B

    Creating Brown Noise with WaveProvider32 in C#

    ok I am new to Brown Noise and DSP but from I read this is how you would do it : class BrownNoise : WaveProvider32 { double T; int N; double dt; Random rand1; float lastValue; public BrownNoise() { T = 1; rand1 = new Random()...
  30. B

    Ocean Noise Generator - MyNoise.net

    http://mynoise.net/NoiseMachines/oceanNoiseGenerator.php how are they making these sounds? it sound a lot better than just pink noise and brown noise...
  31. J

    How can I scale the noise function in a 2D game map generator?

    First I want to mention that I am not super good at maths and that I wasn't even sure if this was the right sub forum to post in (please move this to another one if that's the case). I am working on a 2D game in python where the player plays on an infinite map. Of course that means that the...
  32. A

    How Does Shot Noise in a Photodiode Lead to White Noise Characteristics?

    Not really sure where this belongs... But here goes: If you illuminate a photo diode it generates a current because electrons are being emitted from its cathode. Since each emission is however an independent stochastic process the output current will be subject to fluctuations, which can be...
  33. B

    C# Can someone help me fix the loudness issue with my pink noise algorithm?

    Can someone go over the pink noise algorithm for ? I am not really understand how to make pink noise this is what I did : for (int n = 0; n < sampleCount; n++) { Frequency_Start = rnd1.Next(8); Frequency_End = Frequency_Start * 2...
  34. .Scott

    CSHS Inequality - and noise

    I never heard of the CSHS Inequality until I read it in another thread. The other interesting item was this: I think an important part of that discussion is the more hits are ignored, the easier it is for local realistic theories to score over 2.00. So I just had to try. For those familiar...
  35. M

    Shot noise or avalanche noise

    I frequently see the following circuit being used as a noise generator: ... where the transistors are basic npn bipolar transistors. Some authors attribute the noise to shot noise while others say it is avalanche noise. How do I determine which is correct?
  36. Y

    Which of these op amp configurations has the least noise?

    I need to run a signal through a configuration so that it has a gain of 1/2. I'm trying to figure out what the best way to minimize the noise for a low frequency input. So far I've only really thought of 3 ways to do this: 1. Voltage divider into a voltage follower 2. Measure the input so...
  37. R

    Signal to Noise Ratio: Solving 16-bit ADC Problem

    Homework Statement I need some help with the following problem (from an old exam): A 16-bit single-ramp ADC has a sampling interval of T=1 μs and an input voltage range of 0 to 10V. Since for this ADC the input must be positive, its design includes a fixed DC input of 5 V upon which...
  38. D

    MHB Kalman filter and simulating Gaussian noise

    Water level assumed constant. Static state model \(P_0 = 1000\), system noise \(Q = 0.0001\), measurement noise \(R = 0.1\). I want to use Kalman filtering to solve this problem. I know how to do this but I need to generate \(\mathbf{y} = y\) using Gaussian random noise. \(P_0\) is also call...
  39. K

    Doubt in Noise Vibration and Harshness (NVH)

    What does a first / second / nth order frequency mean physically?
  40. M

    Noise voltage spectral density from datasheet

    Having found a datasheet for a particular component, I have to find the noise voltage and current spectral density. In the datasheet I have values like RTI for a gain of 1000 and Rs=0, but I need to find values for when gain G=100 and for different values of frequency. Does anyone know how to...
  41. ABW

    What is a reason for radio receiver noise?

    Dear colleagues. please help in solving the actual problem: Our company operates in the field of space communications . For reception and transmission of signals via satellite is used parabolic antenna with a diameter of 12 m Frequency of received signal is 4000 MHz. The receiver is a Low...
  42. diemilio

    Understanding White Noise Behaviour in an Ideal Mixer - SNR Unchanged"

    Hello everyone, I have a question regarding the way white noise behaves when passed through an ideal mixer. Picture the system shown in the attached image. Assume the mixer is ideal and that the high frequency contents of the multiplication are filtered out. Therefore the output of the...
  43. J

    Can I Generate a Signal for My Broken Cable with a Homemade TDR?

    I have a 300 foot cable with multiple conductors one is broken what I want is an idea how to generate signal that could be picked up by am radio? Was thinking of trying a crt monitor with copper windings around the outside with one end tied to cable do not know if this would work or some way to...
  44. C

    Signal to Noise Ratio: Definition & Wiener Filter Calculation

    What is signal to noise ratio ? And how do I calculate it with the wiener filter?
  45. J

    Filtering Noise in Digital PID Controllers: Exploring the Electrical Components

    When speaking of filtering noise of an input or output, are the texts referring to the actual electrical components of a digital pid controller? Capacitors, resistors etc...
  46. Mechatron

    Thermal Noise Frequency & Gaussian Plot

    I want to develop a new model for calculating the frequency of thermal radiation. It is generally accepted that thermal radiation emits white noise with all the frequencies within a certain bandwidth. But when white noise interferes with communication systems, it is carried on what is known as a...
  47. Mechatron

    Thermal White Noise - Johnson–Nyquist noise

    I'm trying to measure the thermal white noise generated by chemical batteries. So far I've measured the current noise, the voltage noise (V noise) and the bandwidth (delta v). From the equation below, I'm trying to solve the equation for the frequency. The problem is that there's an...
  48. A

    FIR Filter and Signal to Noise ratios

    Homework Statement A noisy but slowly-shifting sensor signal is being filtered with a low-pass, finite impulse response filter. What is the mean delay and expected SNR boost (noise standard deviation of output compared to input) for two filter variations: N filter taps uniformly weighted...
  49. O

    Signal to noise ratio for thermal and shot noise

    Homework Statement The output of a sensor which produces 10000 electrons is connected to parallel RC circuit with Resistance= 50 ohm, and the capacitance=10pF. Calculate the signal to noise ratio at temperature 300K. Homework Equations SNR= 10 log (power of signal/ power of noise) Or...
  50. dexterdev

    Sampling low pass filtered white noise

    Homework Statement If we filter out ideal white noise using an ideal LPF of cutoff frequency W Hz and then sample it at F Hz , What are the conditions for different F so that the resulting discrete signal is correlated, uncorrelated , statistically independent and orthogonal etc? I would...
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