# What is Shot noise: Definition and 19 Discussions

Shot noise or Poisson noise is a type of noise which can be modeled by a Poisson process.
In electronics shot noise originates from the discrete nature of electric charge. Shot noise also occurs in photon counting in optical devices, where shot noise is associated with the particle nature of light.

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1. ### A Expression of Shot noise when expanding ##a_{\ell m}## coefficients

I would like to arrive at the following expression for the quantity ##o_{\ell}## ( with "DM" for Dark Matter ): ##o_{\ell}=b_{s p}^2 C_{\ell}^{D M}+B_{s p}## with Poisson noise ##B_{s p}=\frac{1}{\bar{n}}(\bar{n}## being the average number of galaxies observed). the index "sp" is for spectro...
2. ### A Relation between a_{\ell m} noise and Poisson noise with C_{\ell}

We assume two galaxy population, ##\mathrm{A}## and ##\mathrm{B}##; the corresponding maps have the following ##a_{\ell m}## : ## \begin{aligned} &a_{\ell m}^{A}=b_{A} a_{\ell m}^{M}+a_{\ell m}^{p A} \\ &a_{\ell m}^{B}=b_{B} a_{\ell m}^{M}+a_{\ell m}^{p B} \end{aligned} ## Here, ##b_{A}## and...
3. ### A Photometric Galaxy Clustering Error and Poisson Noise

The error on photometric galaxy clustering under the form of covariance which is actually a standard deviation expression for a fixed multipole ##\ell## : ## \sigma_{C, i j}^{A B}(\ell)=\Delta C_{i j}^{A B}(\ell)=\sqrt{\frac{2}{(2 \ell+1) f_{\mathrm{sky}} \Delta \ell}}\left[C_{i j}^{A...
4. ### A Add factor Δℓ or Δℓ^2 in the variance for integrated Shot noise

I have the following expression for an error on a Cℓ : ##\sigma(C_{\ell,X})=\sqrt{\dfrac{2}{(2 \ell+1)\Delta\ell \,f_{\mathrm{sky}}}}\left[C_{\ell,X}+N_{X}(\ell)\right]## where ##X## corresponds to spectroscopic/photometric shot noise and with ##\Delta\ell## is the bin width between 2 values...
5. ### A Expression of the mean and variance of spectroscopic Shot Noise

Hello, I would like to know the right expression for the expression of variance of Shot noise in spectroscopic probe. Sometimes, I saw ##\sigma_{SN,sp}^{2} = 1/n_{sp}## with ##n_{sp}## the average density of galaxies, whereas my tutor tells me that ##\sigma_{SN,sp}^{2} = 1/n_{sp}^{2}## , so I...
6. ### Poisson distribution and Shot Noise

My setup: I have the an LED (LED370E) in front of a photodiode (S12915-16R). The photodiode is connected to an ADC (DT5751) which has a counting functionality. The way it works is that it counts how many times the signal goes above a certain threshold and makes a histogram out of it. I know...
7. ### Acoustics (Environmental Noise): LAFmax vs Shot Noise Level?

Hello, new poster, I am trying to do a fairly simple, but non-standard, environmental noise model run for a shooting range. The standard against which noise from the shooting range is to be compared is the Shot Noise Level (SNL). SNL is defined as the logarithmic average of the 25 highest...
8. ### 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...
9. ### Shot noise in a photo diode

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...
10. ### 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?
11. ### 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...
12. ### Squashing Shot Noise - help please

Citizens of Physicsforums. I would greatly appreciate your advice. I've been wrestling with a pesky noisy phototransistor for quite a long time, and am at wit's end. The sensor is being used to transuce an audio signal in the 1-5kHz range. Unfortunately the shot noise is introducing...
13. ### Photocurrent shot noise correlation function

Hi I have stumpled upon the following expression for the correlation function of the photocurrent shot noise for a photodiode <\delta i(t)\delta i(t+\tau)> = \frac{e^2\eta}{h\nu}P\delta(\tau) where η is the quantum efficiency and P the power in the signal. δ(τ) denotes the Dirac delta, which...
14. ### Modeling shot noise on Mathematica

I've been having some trouble modeling shot noise for a photomultiplier tube on Mathematica - I know that I have to use a random number generator and the Poisson distribution to do it, but I'm having trouble synthesizing everything. (There are many things I'm going to leave just as parameters...
15. ### Johnson and Shot noise the Frequency Term

I am a bit confused over the frequency term that appears in Johnson and Shot noise formulae. What is this term? Is it bandwidth? Of what? In relation to say a photodiode, is it the range of frequencies being detected? And how would this relate to say a DC circuit which no frequency terms...
16. ### Johnson and Shot Noise at 20*C with 9V Battery and 100Kohm Resistor

A battery of emf 9V, and negligible internal resistance, has a 100Kohm resistor connected across its terminals. What are the values of johnson and shot noise at a temperature of 20*C if the measurement bandwidth is 10KHz? At what temperature would the johnson and shot noise contributions to...
17. ### MATLAB Adding Signal and Shot Noise in MATLAB - MB's Question

hello well I have 2 vectors in MATLAB each representing a signal+shot noise. I have to add them. Can anyone tell me what the signal noise ratio will be when they are added? thanks MB
18. ### Johnson noise & Shot noise

I was wondering if someone could give me some ways to combat Johnson noise and shot noise. Thanks
19. ### Exploring Galaxy Surveys: Shot Noise Estimation

I am reading about galaxy surveys. I want to know what is shot noise ? how we estimate it into real and Fourier space ? I am basically reading astro-ph/0503603 & astro-ph/0503604. I am not able to solve exercise 4, 5, 6. I will be thankful, if anybody can provide me some reference.