Noise Definition and 474 Threads

The diaphragm in a dynamic microphone moves a wire coil in the presence of a magnet to induce a current related to the movement. Other types of microphones, like electret and condenser microphones have self noise - noise not attributable to the amplifier. I wonder if all of the "self noise"...

Would the frequency spectrum of Johnson noise change at all when a magnetic field is applied? My guess is not much, since the field changes only the direction of motion of the electrons, not their speed.

Hello everyone, I have a few questions regarding the principles behind XRF spec, as most of the sources I've consulted either don't go into enough detail and miss bits out (undergrad textbooks), or are simply beyond my current level of understanding (QM papers etc). When, for example, a...

Vibrations of a motor (40Hz) cause noise on the signal of a strain gauge that monitors load on a cantilever that measures periodic load changes at the rate of 1/minute. Design a filter that reduces the signal caused by the vibrations by 90%. I thought about a low pass filter that has a cut...

Hi Everyone I am new to this forum. I currently work for a company that uses a flow waterjet. It is an awesome machine but of course it can be super loud. I am in the process of researching a way of reducing or even canceling out the noise that it produces. I believe that Active Noise Control...

This question concerns estimating the PDF of noise, based upon observations of a data stream consisting of noise embedded with transient signals. I would like to know if my Proposed Solution is a correct approach. Suppose I have "long" stream of seismic data, consisting of noise, and with...

hi.. can someone help me out with noise in engines.. i am specifically interested in noise due to running of chain on sprockets.. it is a sort of whistling noise... which are those parameters in design of sprocket and chain which contribute in noise.. we can also talk in terms of different...

I am trying to create noise that has similar spectral properties of a recorded tapping sound (so that I can mask the tapping sound). I was thinking that if I generate noise, and then multiply the fft of the noise by the fft of the tap sound, it would sort of "filter" the noise to the desired...

I read about 1/f noise. It says it is inversely proportional to frequency. What would happen at zero frequency or dc? Will it go to infinity? But when we measure some dc value we don't find any infinite voltage which clearly disproves this equation. What is the reason behind this? Thanks in...

Hi. I have a few questions about sensor specifications and its implementation in a Kalman Filter and simulation of gyroscope/accelerometer output. Abbreviation used: d - discrete c - continuous Q1: From book: Aided Navigation - Farrell (you don't need the book to understand the...

I would be very interested and grateful for guidance on how viable it would be to contain a noise in a relatively small area. If the aim was to contain a noise through passive and active noise cancellation and the noise source could be contained within a small area, could the technology used in...

I'm looking to use the MAX31855 thermocouple-to-digital converter, to measure temperatures in the range of 0-350C. According to the manufacturer, the ADC inside the chip is identical for every different type of thermocouple, just a different sensitivity is programmed in depending on the type of...

As the title says, a guitar effect I built introduces a lot of white noise, which goes away when I touch it's case. I removed the circuit from the case and found the noise also goes away when I hold the input sockets. How do I fix this? Thanks for any help!

Homework Statement Suppose you have two sensors with rates of noise R_{A}^{noise} and R_{B}^{noise}. Suppose an erroneous signal occurs if the two sensors have a noise trigger within time \tau of each other. Show that the rate of false signals is R_{AB}^{noise}=2R_{A}^{noise}R_{B}^{noise}\tau...

I want to make sure I understand what I am reading in various spec sheets when they quote their noise measurements and I hope that you-all can confirm that I am on the right track. Take the OP27 Op-Amp as an example, which is described as a low-noise precision operational amplifier...

We know that when sound travels through solids like a wall, the air molecules interact with solid molecules in porous medium to transmit the information hidden in sound wave.The question is that why no noise is added to someone's voice when we hear it from other side of a concrete wall ?

Pretty self explainable. Why do they not create a sonic boom when they enter Earths atmosphere

Hi all, I want to measure the white noise produced by a resistor in my circuit. In order to do this I did the following: 1. Ground the excitation voltage of the circuit and measure the white noise voltage produced by connecting the output of the circuit to a 8.5DVM 2. Subtract the Avg DC...

Hi, my problem involves a laser sensor as a bin level sensor. what i want to do is get rid of the noise from the signal obtained. the spikes in the picture below are because the location of the laser sensor has to be where it is and when large rocks move down into the chute they pass infront...

Hello I have been doing a set of experiments in order to try and measure the current noise of a thick film resistor. I basically attach a low noise, power supply, to a thick film resistor and slowly increasing the power supplies voltage to that resistor. I am noticing a strange phenomena...

There's just no way to ask this without imagining the smirks and jibes I'm going to get, so make em good. There's a noise inside my head. I am not looking for a diagnosis, this is just curious conversation, and I will most definitely to go my doctor for any advice. Every once on a while...

I have values of time, and volts of a noise signal. I am trying to determine the noise power, signal to power ratio and bit error probability. How would I go about doing this? Thanks.

Hello, I was wondering if anybody could answer a quick question: What is the typical level of Johnson-Nyquist noise in an analog voltmeter in equilibrium (short circuited)? Is it millivolts? What is the level for an AC current of order mA at 50Hz?

Fourier transform of "noise" Hello, when we want to get the magnitude of the Fourier frequency spectrum of a function f we typically calculate F(\omega)=\int_{\mathbb{R}}f(x)e^{-i\omega x}dx and then consider |F(\omega)|. We can do this as long the signal (=function) is deterministic, that...

All the models I see is mostly common emitter, I have a circuit with AC equivalent shown in Fig a. Where v_s \; is the signal voltage and the source resistance R_s. I want to calculate the equivalent input noise voltage. Here is what I attempt to do it: 147190[/ATTACH]"] I show the equivalent...

I have to isolate the cell(seen as a bright blob) in the attached images from the background the zig-zag. The problem is essentially that the intensity/brightness of the cell is almost equal to its backgraound, so I can't just subtract frames!

What is the main frequency components of noise from AC line, florescent lights, appliances and other common household stuff? I know there are 60Hz and 120Hz from rectifying. Do I have to worry about 180, 240, 300, 360 ( 60X1, X2, X3, X4, X5...) etc.? Which one are the strong ones?

Hello, So I have a question about electric power lines. Today I was under some large power lines and I noticed some ticking noises. I had never noticed this noise before and was curious I thought maybe the current flowing through the lines was too great, and the lines were arcing to...

Hello, I have some 10 signals in noisy and nonoise(noisy+good) situations. I just calculated the power of each signal in two cases and then used SNR formula for dB(10log noisy/nonoise). Now, I got noise levels in dB's. Here, i confused that these dB levels are referred to...

So I have been taught about FM having noise supressing characteristics, but in that particular course the lecturer told us not to worry about it as it is out of the course syllabus. So I tried to look up on the details on the internet but all I keep seeing is that FM supresses noise but I...

Hello, I have a waveform that have noise when my pump stroke hit some mechanical part. i have converted the waveform into frequency domain to see the noise frequencies. I don't know the actual original frequency of the pump but i just decresed noise by stroke not touching the...

I want to generate a Gaussian white noise as an input to a vibration exciter. Since, it does not follow the high frequencies I need to low pass filter the signal. I need to implement a filter which makes minimum distortion to my signal in terms of temporal correlation of the filtered signal and...

Hi guys, its been awhile since i have been back. Right now, i am involved in some research on aeroacoustics and i have been trying to get some of the basic fundamentals on aerodynamic generation of sounds. Unfortunately most of the online literature do not give much details on the physics of...

This unique 6-minute video shows a she-bear and her two cubs devouring a seal, while mummy bear is growling for miles around to be heard, to warn off others from getting too close. http://www.dagbladet.no/2011/09/07/nyheter/innenriks/isbjorn/dyrenes_nyheter/17989869/

Hi I have a HV (R2) resistor that I want to test for noise. Assuming the 2 low voltage resistors are perfectly stable and HV R1 is also perfectly stable. How could I completely cancel out the noise of the power supply if the bridge was slightly unbalanced? Does any circuit exist that can do this?

In my textbook it says this: "Digital communication, which can withstand channel noise and distortion much better than analog as long as the noise and the distortion are within limits, is more rugged than analog communication. With analog messages, on the other hand, any distortion or noise, no...

I started an electrical engineering degree this semester. My book says that electrostatic noise meaningfully affects analog but not digital. But it does not say what electrostatic noise is, and neither Google nor Wikipedia readily yield an answer to this question: What is electrostatic noise?

Is it possible to cancel noise from an air compressor while still allowing air flow to keep it cool?

Hi everyone, This is not a homework question but I question I have from reading a signals processing paper on acoustics. Suppose there is a sound source in a room S(t) and two microphones X_1(t) and X_2(t). Then the standard acoustic propagation model has that X_1(t) =...

Dear all, I am trying to understand something for SNR, I know that is the ratio of the Power of a signal divided by the Power of noise. According to wikipedia Signal-to-noise ratio is defined as the power ratio between a signal (meaningful information) and the background noise...

Suppose I have 2 sets of data: day1 and day2. I want to fit a model to both data sets and then compare them to each other to see which one fits the model the best (the fit is done with a computer using non-linear least squares method). The RMS of the fit would be fine except that day1 has much...

My employer has asked me to derive a method or equation for determining noise (in decibels) in orifice flow meters. I was wondering if anyone has any suggestions that could help me get on my way? I've been looking at basic principles of aerodynamic and hydrodynamic noise predicitions. As far as...

How to calculate the effective noise power spectral density, when a noise factor of 3 if given and if said to make any assumptions. We know Effective Noise Temperature N = k.Te.B I'm assuming it as Te = 290 K x (10 NF/10 - 1) and what about 'B'?

The ourput Noise Power is given as No = kTsBG + kTeBG ...= k.(Ts+Te).B.G But when it is asked in dB or dBm, How to calculate it something like 10Log10(Value) or 20Log10(Value)

I have built a 3' by 4' hovercraft (with rounded corners) out of plywood with a pond liner bag skirt. it it powered by either 2 battery operated leaf blowers or 1 plug in electric leaf blower. I have encountered a problem with both power sources. The hovercraft makes a loud vibrating noise...

Hi everyone, I have recently built a Faraday Cage. However it seems to be working in reverse and amplifying the noise! My test setup: I place a 3.3 Mohm Bulk metal precision resistor across the terminals of the meter and measure the pk-to-pk noise using the meter. I now place the meter...

My research involves using a detector that I am trying to test with a pre-experimental setup. To test the functionality of the detector, I am pulsing a light source near the detector using a Picosecond Pulse Labs pulse generator. Here is where my troubles/question comes in: the pulser is...

Newbie here, not an EE, just an old Air Force electronic tech from the 70's...please be gentle. :) I recently installed a noise suppressor inline to the 12v on my 70 Lincoln AM/FM radio. It cleaned up the "whining" noise just fine - but one interesting side note is that my FM stations come...

Hello, In the chapter on thermal noise it says that the spectral distribution per Ohm of resistance is a certain shape (constant till a certain f and then ~ 1/f²). What is this expression? Is it physically the power dissipitating in the resistor, at least a certain part of it...

Is there any specific theory that states how we can remove noise from audio out put. I am a developer. I know no basics in terms physics about Audio, Noise . I record audio using an application in iPhone. I get lot of surrounding noise. I wanted to remove those noises. Is there any algorithm...