Noise Definition and 474 Threads

yellow line: output of photodiode which detects an LED blue line: output voltage to the LED newfile1: the file without measuring using average of the scope. newfile6: the file with using average of 32 times of the scope. How to filter the noise? It's noisy, I find it's ok to use...

If you have a lump of metal would it make a louder noise if it hit glass or metal?

1. Is thermal noise truly random? By truly random I mean can you not predict the next value even if you knew everything permitted about the electrons producing the effect. Does this follow from the math of quantum physics? 2. What about nuclear decay is it truly random?

Does a function exist (prefferably in matlab) that finds a function in noise Cheers

I'm working on a laser interferometry system that uses a pair of balanced photodetectors to record the signal. Each detector is on a separate port of a beamsplitter cube, and as a result receives (in theory) the SAME signal. The rationale for using the balanced detectors is that "they reject...

Hello everyone. I am new and have a question. I just got a Tektronix 2246 Mod A Oscilloscope. Everything works great on it. The CRT seems to have some "sparkle" or "noise" in it. It is very slight and it is visible both on the traces and the readout. It looks like the traces and readout...

ultra sensitive microphone or technique for listening to inner ear A friend has very loud tinnitus. He says it is constantly louder than anything else he can hear. Nothing can be heard by an independant observer such as myself, but it is possible that a sound with a small power level is so...

I'm attempting to clean impulse noise from a wave file in matlab. the file is two channels, about 7 million points in each channel. What I wish to do is keep points, that are below my trigger levels, and delete points (in both channels simultaneously) that are above the trigger levels for either...

Hi, I am using a simple circuit in the lab which detects current flow from an ion source. These are transient signals recorded at a rate of 100Hz. The problem is, the ion source is switching at the same freqeuncy at very high voltages. Needless to say there is a fair bit of 100Hz EMI. So...

I have two overlapping Gaussian distributions. One for probability of a noise event, one for probability of a signal event. My noise distribution has mean = 0, variance = 1, and standard deviation = 1. My signal distribution has mean = .80, variance = 3, and standard deviation = √3. My...

Do you have a constant noise in your apartment due to air conditioner for the building or nearby building? If so how to you get over it?

Hi The company I work for has a Dyno room for tuning its engines before sale. Can someone advise me on an electronic noise retardant please? The room where the Dyno is situated is quite small and doesn't really have the ability to be lined with a material unless it were less that 25mm thick. Penn

Can someone please explain to me or preferibly point me torwards a resource that will explain what is ment by noise? I know that it s some kind of unwanted disturbance in a signal and that we want to get rid of it, but where does it come from. when i search online about this i find a myrid of...

while dealing with radio telescopes how can we remove the noise and other disturbances like microwave radiation etc.

hi for every one I am a new member in tis site. I hope from u to help my I have a hmoework so I want some help The question is What is the source of noise in amplifier & how can treat the noise? Thank u

Just a couple of weeks ago, my laptop started making a very loud roaring noise and experienced a severe slowdown in performance (programs and windows open very slowly) at the same time. It takes a couple minutes after booting up for the noise to begin, but once it starts it is continuous. At...

Hello everyone. I'm not a Physics major: I'm a Music major. And I have a question. I've read various books on acoustics, but I still haven't found the answer. Ok. The way I see it, there are 2 basic types of sounds (I didn't get this out of a book, it's my own conclusion from everyday...

Hello everyone. I'm not a Physics major: I'm a Music major. And I have a question. I've read various books on acoustics, but I still haven't found the answer. Ok. The way I see it, there are 2 basic types of sounds (I didn't get this out of a book, it's my own conclusion from everyday...

Hi, Is it possible to calculate the gain of a closed loop system with Noise? Here's a diagram describing what i mean: http://img206.imageshack.us/img206/8955/cltfmh8.png I've got the following so far: Vout = \frac{A1A2Vin}{1 + A1A2B} + \frac{AVn}{1 + A1A2B} But the question is...

Homework Statement We are using Raman spectroscopy to detect the presence of chemicals from emitted light. We have a light transistor that behaves as a photo-resistor of 50k-ohm resistance. The light signal generates 2 microvolts of 2 kHz signal at normal Raman levels. We want at least...

Hey friends, Can you help me with the questions posted below ? a) How can noise affect an electronic system and the consequence of each ? (3 points) b) Noise is difficult to measure and characterize. State the reasons. (5 points) c) How do the choices of frequency and wavelength affect...

hello, I am stuck at understanding the units of noise specification of accelerometers and gyros. I am referring to the datasheet of 3DM-GX1 which has accelerometers and gyro sensors. the pdf is .. http://www.microstrain.com/pdf/3DM-GX1%20Detailed%20Specs%20-%20Rev%201%20-%20070723.pdf...

What causes the feedback (a noise increasing in intensity and pitch) sometimes heard when people speak through microphones? I'm sure I have enough background to understand an explanation, I've just never thought about it before.

Thermal noise known as “Johnson noise” or “Nyquist noise” is well known and characterized. This noise is a result of thermal agitation of charge carriers inside a conductor. Its power spectral density is given by: v^2=4kTRwhere kB is Boltzmann's constant in joules per kelvin, T is the...

Hello, I'm designing a circuit with a linear regulator to supply power to an RFID reader. The input to the regulator is 12VDC supplied by an ordinary external AC/DC desktop switching power supply. When I look at the output of the linear regulator with a scope it looks pretty clean except for...

Hi, first of all, excuse my very poor englishI have a big problem with a bar in front of my window, in the middle of a little park. They close very late (ignoring the closing hour stablished by the law) and they make a horrible noise. Here (in Spain), there is very passivity applying the...

Hi, whenever i play sound using the laptop speakers i get a buzzing noise which gets louder with louder sounds. It sounds like a motor (but i couldn't hear anything loose rattling about) anyway when i plugged in some speakers the sound was fine and when i took them out the buzzing was still...

Noise cancellation through interference; I guess most people here know what I am talking about. My question is: where does the energy go? In a (sound)wave there is constant exchange between kinetic and potential energy, or at least that's how I see it. Now the wave gets canceled...

CCD readout noise problem! Hello all! does anyone know how to calculate the readout noise of a ccd? i have found values for proffesional and amateur ccds on the net but as far can't find any method of calculation. what does the value depend on? charge transfer time? number of electrons...

Noise handling algorithm in 8 wire touch screen here's how a touch screen work http://focus.ti.com/lit/an/slaa298/slaa298.pdfProblem: when the touch pen is stationary on a point and reading ADC values from a touch screen using the micro controller, the ADC values are never the same eg, 1st...

I just watched Finding Nemo, I don't like Dorie !

hi all - its been very long - hope everyone is well! just a data comms related question: When modelling a communication channel we normally include AWGN, that is, Additive white gaussian noise. Can anybody tell me why we use white noise in the model. I know it has a constant power...

This may be of interest to readers: http://www.flightglobal.com/articles/2007/01/23/211641/airbus-a350-xwb-set-to-be-quietest-generation-of-airliner-as-manufacturer-improves-zero-splice.htm A noise reduction engine nacelle intake. "A zero splice liner with a continuous surface and lacking...

What is represented by the -1.0 to 1.0 range of this graph? Four thousandths of a second of white noise: http://upload.wikimedia.org/wikipedia/en/thumb/5/55/Whitenoise.png/350px-Whitenoise.png I am not sure what I am looking at. It's from: http://en.wikipedia.org/wiki/White_noise

I have two simple questions but I'm not 100% on how to get the correct result. 1. "The noise is reduced by 6 dB" means its amplitude is cut to _%? How is it calculated to 50%? I try 20log(Av)... 2. Does this wave contain 30k hertz sine function? (see attachment) The answer is yes, but I...

I was wondering if someone could give me some ways to combat Johnson noise and shot noise. Thanks

Hi all, I have a high gain current to voltage amp connected to 2-3 meters of coax which is picking up noise in the 7-10.5 kHz range. Does anyone have any expereince in waht could be the source of this noise? Right now I'm using a couple op-amps and a low pass filter to get the noise to a...

I know that purpose of the preemphasis filter in a noise reduction system is to increase the amplitude of the input signal at frequencies where SNR is low prior to transmitting the signal. I also know that a deemphasis filter is located at the receiving end and its purpose is to undo the effects...

For my time series and spectral analysis class i need to graph something like in the attachment. i need to have 100 numbers that are connected like that, and then 'add' them to a sinusiodal wave to create a real life wave - with noise. How would i do this using mathematica?? I can easily...

Is it true that a "high" input of a TTL gate shouldn't be left floating but instead connected to +Vcc through a pullup resistor because this way the propagation delay time is reduced and less noise is captured? If that's true, should a pullup resistor be used when connecting the input of a...

Please move to appropriate forum if necessary. I need some help. Attached is a pic of my standard 1/4hp Hayward pool pump. I want to enclose it to make it quieter. (The sound is being transmitted by air rather than by physical contact.) As a "proof of concept" I stuffed it in a storage bin...

Dear Sir or Madam I have some troubles regarding the noise subject. Would you mind to help me solving the following problems? Thank You. 1. Under what condition will sound power level be lower than sound pressure level? 2. L10, Leq, Lmax ~ How are they related to noise fluctuation and...

Hi all I want me to explain what white and black noise is .And what's the difference betwween them?

The theory is that sound is heard because of fluctuations in the air molecules that surround us but why is that we can hear noise coming from outside when we are in an enclosed room? Is it the case that air molecules are able to travel through the walls of an ordinary room?

Hello. The ac contactor with two magnets sometimes give a noise.For some contactors humming is more audible.What are the possible causes of humming. Also what is the effect of humming on performance of contactor.Can anybody help on this subject?

help! with building a circuit. i need a gain of 300 (not exact, but somewhere around there, 200-500) for a small signal (typ. 0.1mV to 5mV) AC input with a bandwidth from 0.5Hz to 120Hz. I need it low-noise, with high precision and reliability... has anyone got a reference for any sort of help...

My mouse is causing noise in my speakers whenever I move it. I can't exactly explain the noise, but it's quite and wouldn't be noticed if perhaps the television was on or I had an mp3 playing. I tried muting the speakers from the volume control panel in windows XP, but I could still hear the...

My question is quite simple: It is common knowledge that most metals make a lot of noise when in contact with moving/vibrating parts. Some examples are the hood of your car, or a computer case with fans on it. Does wood have the same characteristic? I want to use wood to mount a few fans...

I posted the details of myquestions earlier but no help. Maybe I need to rephrase it. I basically generated a square wave and added noise to it using Matlab. The question is how do I design a filter to reduce as much noise as possible to retain most of the square wave. The SNR is OdB...

I’m generating a 1 kHz square wave and adding Guassian noise to obtain a SNR of 0 dB (using Matlab6.5). The task is to design a filter that will filter out as much noise as possible from the square wave plus noise signal. The sampling frequency is 100kHz. Noise signal: 100.0*randn(1...