Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [noise]

Noise is an unwanted disturbance in an electrical signal. This tag is for questions about sources of noise, noise types, issues caused by electrical noise, or improving the signal-to-noise ratio of an analog circuit.

Noise is an unwanted disturbance in an electrical signal.

Occasionally we deliberately generate white noise or pink noise (such as in generators).

In all other circuits noise is a problem we try to minimize.

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Why use LNAs in a noise generator?

In this Maxim appnote the avalanche noise of a zener diode is amplified by two cascaded LNAs (Low-Noise Amplifiers): You can guess what my question is: why use low-noise amplifiers if you want noise in the first place? Don't ordinary opamps…
Federico Russo
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What's with all this noise?

People often talk about noise in circuits. Cheap op-amps are noisy, running a motor can create noise on the supply, and a lot of analog circuits deal with the signal-to-noise ratio (ie: trying to keep the noise floor low). My intuition is that noise…
Greg d'Eon
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What does "correlation" mean in signal processing?

What do the words "correlated" and "uncorrelated" mean in signal processing? E.g. - "uncorrelated white noise.."
Let It Be
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Do internal noise like thermal noise in a system extract power from the DC supply?

I have read that noises like thermal noises are due to high temperature causing random agitations in electrons etc.But one student was asking me that whether power is extracted from the DC source etc for generation of noise like thermal noise in…
dexterdev
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What would the units of thermal noise be?

This came up during an assignment question, but is a tangent. Thermal Noise is given by; N=k T B where; k= Boltzmann's Constant (J/K) ir (W-s/K) T = Temperature (K) B = Bandwidth (Hz) That would mean that the units of thermal noise can be…
Michael
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Infinite thermal current noise in a wire?

The thermal noise density can be written as: $$nd_V=\sqrt{k_BTR}$$ or $$nd_I=\sqrt{\frac{k_BT}{R}}$$ The units begin V/sqrt(Hz) or A/sqrt(Hz). For the second expression, does this imply infinite current noise density for an ideal wire? This seems…
student1
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What happens to noise after crossing through a bypass capacitor?

I understand that bypass capacitors provide a lower impedance path for oscillating noise. However, capacitors aren't able to dissipate energy (apart from their effective series resistance), so all the noise should get to ground almost without…
Gabriel Corrales
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Does a battery powered resistor have Johnson Noise?

The mean noise voltage for Johnson (Thermal) Noise is given by the formula: \$ v_n = \sqrt{4kTR\Delta{f}} \$. The bigger the resistance of a resistor or the higher the frequency of a voltage supply, the higher the thermal noise the resistor will…
KMC
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Are the noise floor and signal to noise ratio same things?

I have a problem in understanding clearly what noise floor is. The term SNR is more clear which is the ratio of the signal to the noise in dB. In wiki the term noise floor is explained as: In signal theory, the noise floor is the measure of the…
user1245
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Optimizing a circuit for noise immunity

Followup to this question. I have a circuit with three instances of this pulse detector: simulate this circuit – Schematic created using CircuitLab C1/C2 not present yet - therefore the 0F value. R2 varies from one circuit to another (20K-120K), to…
jmr
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How to suppress terrible noise from MAX7219?

On the same power supply I have connected MAX7219, which is producing terrible noise to amplifier so I can hear refreshing frequencies of MAX7219. If I hook up amplifier to battery power supply the noise is gone. I've also tried to connect 220uF…
Pablo
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Hum on car stereo when source powered by inverter

I have an auxiliary input on my car stereo, which I plugged my laptop into to play music with. It worked fine until I plugged my laptop into an inverter so the battery didn't die. An extremely noticeable hum started coming through the speakers…
jdickson
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Noise cancellation for electromagnetic signals

I am working in the oil field with tools which I need to connect by cables (which "should be shielded") to computers. Most of the time when I communicate with my tools, I face grounding issues. I tried to ground the computer but it didn't always…
Ahmed Dorry Negm
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Origin of micro Hz noise signal

Latetly we recognized a parasitic signal in our voltage measurements. It is a perfect sine wave with a period of a few hours (f = uHz). What could be the origin of such a signals? Ok, a few more details: We do Hall-Effect measurements in a cryostat.…
P3trus
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How to avoid input noise?

I'm playing with UDN2981 source driver IC. But its inputs are so sensitive that the noise collected by connector wire switches them on. A simple touch is enough to set it on, but actually I don't want to make a touch sensor :) I tried using pulldown…
csadam
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