Questions tagged [noise]

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How is MRI SNR affected by the frequencies that are included?

So for MRI imaging, if an image is taken, and portions of the Fourier transform image are removed so that some portion of the higher frequencies are not included, would this reduce the SNR? I assume ...
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45 views

Active noise canceling for CNC enclosure

this is my first post here! I wanted to share my ideas for this and get some input on them. My parents were kind enough to let me put a cnc machine in the loft. (shapeoko 3 xxl) In order to make them ...
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2answers
50 views

How to convert the velocity field to a pressure field for obtaining the sound level?

I am studying jet mixing noise and I am given a velocity field, with $V_x$, $V_y$, $V_z$ in the Cartesian coordinates. I wanted to know if there is a method by which I could find some information ...
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26 views

Understanding the RMS noise for a given bandwidth

I would like to ask a technical question regarding the current source Keithley Series 2400 Model 2450. I am looking for a high stability current source capable of feeding some Hall probes with a ...
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3answers
103 views

How do AC/DC Adapters (Wall Wart) prevent AC Noise Coupling to DC?

I am wondering if AC noise (EMI) gets coupled to the DC side of the AC/DC adapter, what are the design methods used to isolate AC noise getting coupled to DC output in an AC/DC adapter. What are the ...
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29 views

allan-variance noise terms of MEMS accelerometer

Specific noise terms are given in datasheets of MEMS sensors. In example the specification of accelerometer contains information about random walk and in some cases the bias instability. Both ...
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3answers
127 views

Why does audio equipment buzz/humm when a long signal cable is used and how do I eliminate it?

I have two 5.1 speaker sets, one in the front and one in the back of my living room. I have connected them together with an "audio wire" (non-shielded unfortunately) that's 12 meters in length. Since ...
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1answer
42 views

Linear actuator with low vibration and low noise

Which kinds of linear actuators offer the lowest levels of noise and vibration? I am looking for an actuator with these properties that can push a load vertically on the cm scale. Velocity, accuracy ...
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1answer
61 views

How do I calculate hourly LAeq sound pressure level using 1-mint LAeq values?

I have continuous A-weighted sound pressure level (SPL) values at 1 minute time resolution (LAeq,1min). I would like to calculate ...
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1answer
36 views

Noise sensitivity transfer function

Consider we have a second order system (plant) described by the following transfer function: $$ P(s) = \frac{b_0}{s^2+a_1*s+a_2} $$ which is controller by a PD-controller: $$ C(s) = K_p+K_ds $$ ...
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1answer
139 views

How to reduce oscillations (rapid changes of control signal) when controlling a real system, which occur due to noise in measurement from sensors?

I have a real mechanical system (ball & beam) which I want to control. The system is approximated by the second order transfer function: $$ T(s) = \frac{b_0}{s^2+a_1s+a_2} $$ and in state-space ...
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21 views

Meaning of SNR in Instrument Specifications

I am evaluating the specifications of an FTIR instrument (Bruker Vertex) and came across the following statements/items: Signal-to-Noise 5 sec sample, 5 sec reference: >10,000:1 (<4.34 x 10-5 ...
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1answer
53 views

Sound level emissions (IEC 60704-1) spectrum?

I have a very noisy air conditioner that have a 10kHz peak at 75 dB, the rest (fan/compressor/pump) are under the regulation limit. I would like to understand what is the measurement spectrum. I ...