Questions tagged [signal-to-noise]
The signal-to-noise tag has no usage guidance.
155 questions
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Is it sensible to always use larger diameter conductors for carrying smaller signals?
This question as originally written sounds a little bit insane: it was originally asked to me by a colleague as a joke. I am an experimental NMR physicist. I frequently want to perform physical ...
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9
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Why Decibels are used to measure Signal to Noise Ratio?
We just started a communications course in college and we came across SN ratio. The following is an ambiguity I am facing which my professor is unable to resolve:
Signal to Noise Ratio is the ratio ...
- 301
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7
answers
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Amplifying a nV signal across a small resistance
I am interested in the feasibility of amplifying/measuring a nV level (or otherwise assumed very small) signal across a small resistance.
The SNR of this signal isn't so bad in itself because of the ...
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Why is one return conductor for each forward conductor in a ribbon cable better than a shared return conductor?
I don't understand why second way of implementing is better than the first one? I have my own basic logic regarding this topic, but i am not confident if what i think is correct! so i was looking ...
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Attenuator noise figure and loss
My question is with regard to how attenuators effect noise. From what I understand
$$
\text{NF} = 10\log \left( \frac{S_{in}/N_{in}}{S_{out}/N_{out}} \right) = 10\log \left( L \frac{N_{out}}{N_{in}} \...
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5
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Detection of signals buried in noise
This is more of a general question to see which methods are the most common to improve the detection of a signal which is buried in noise. Currently, we are building an optical system for medical ...
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5
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Does "a signal is buried in noise" mean that the noise amplitude is still smaller than the signal amplitude? (Special case: Lock-in amplification)
I heard that Lock-in amplifiers (LIAs) especially play to their strengths when the signals are weak compared to the noise level. But then I talked with someone about it, who understands the principles ...
6
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2
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How to amplify a tiny signal riding on a large common mode square wave
I have a small signal of about 10uV-100uV riding on about 1V common mode. I have tried to depict this in the picture. I am interested in designing a board level circuit(cannot use a commercial lock-in ...
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2
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False Positives on Arduino Input
I've used analog and digital input for a multitude of applications with the Arduino Uno board. It has continuously given extremely non reliable readings, where the analog input is always fluctuating, ...
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6
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1
answer
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Charge, Voltage, or Current? What can be measured with the highest SNR?
Suppose I have a Faraday cup and a certain number of ions hit the detector. What is the highest signal to noise ratio way / circuit to measure this... does one measure the charge (coulombmeter), ...
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2
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510
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Inferring DC performance from a Sigma Delta ADC datasheet noise floor figures
So ive been playing with some Sigma Delta ADCs, for sampling low frequency (<2Khz) AC signals.
The ADC supports a differential input with a full scale value of about +-500mV at its inputs. I have ...
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Trifilar Transformer Common-Mode Rejection Circuit (Signal Recovery, Hybrid Combiner, RF)
I'm trying to develop a circuit that allows me to effectively subtract two different sources of RF noise from a single signal at the same time. I am planning to use something called a "trifilar" ...
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4
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How to select gain for an amplifier before ADC?
The circuit has been simplified as shown in the picture. Signal source is connected with an analog amplifier, which amplifies the ac signal and also raise it by 1.5V to match with the range of the 0-...
- 1,622
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Does antenna arraying for deep space communications affect the CMB contribution?
My question pertains to the reduction in SNR achieved by arraying parabolic antennas in deep space communications. My engineering education is a bit out of date, so my thanks for your patience.
I ...
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2
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White Noise Equivalent Bandwidth (NEB)
This question is regarding White Noise Equivalent Bandwidth (NEB).I was going through this material from Renesas .
The definition of NEB is given as when running white noise through a first order low-...
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How to extract ENOB from LTSpice simulation and see the effects of oversampling?
I have a fully differential instrumentation amplifier circuit with a gain of 536 to map a 3mVpp signal (centred around 1.65V) to +/-1.6V, as shown here.
My signal bandwidth is 250Hz, and I would like ...
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2
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Signal averaging CCD
I'm thinking about signal to noise ratio of CCDs and I hope this is the right location to post my question. The Hamamatsu Learning Center seems to be a good starting point to learn about CCDs. I ...
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2
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Decreasing ADC Reference vs. Amplifying signal
I have a sensor interfaced to ADC but the Range I am getting is not enough, so now there are 2 options, Gain up the signal or Reduce ADC Gain.
But as I heard it, reducing ADC gain will cause more ...
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2
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How does Hybrid Ground Works?
The text that is above the figure is from my textbook and i am having difficulty to understand what it is trying to say because it's not in detail!! why only remove high frequency and prevent low ...
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4
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1
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How is noise reduced using a sigma-delta converter?
Perhaps I'm sleepy but I can't quite get my head around how a sigma delta converter takes the noise that is in a bandwidth of (X) Hz and by over sampling spread, that same amount of noise over 2(X)Hz. ...
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4
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1
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Am I using Shannon-Hartley Theorem and thermal noise correctly here?
I'm trying to learn about noise, sensitivity, and the Shannon-Hartley theorem, and I'm using some specs for a LoRa node IC to try it out.
The Shannon-Hartley theorem says that the maximum data rate \$...
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What do you call the dynamic range of a variable gain amp?
Dynamic range is the ratio of the largest signal a system can process to the noise floor of that system.
If the system has variable gain, though, then you could interpret this two ways:
Fixed gain ...
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How did old mobile phones amplify signals lower than the noise floor?
In the early days of GSM in around 2000 when the network was still not fully deployed, it was common for me to receive very low signal, even sometimes No Signal due to out of network.
I used to use a ...
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Op-amps, why do they have such low output currents
An introduction to my question is that ultimately op-amps drive something with their output stage (i.e., they source or sink current). I am looking specifically at the current sourcing scenario for ...
3
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2
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2k
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How to characterize SNR for an amplifier with extreme low input signal?
Often that the OPAMP has an internal noise of 1uV. If I have an extreme high gain of 10000, the noise will be amplified up to 0.01V.
Then, when I input a very low input signal of 10uV, after amplify ...
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2
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What is the core concept of SINR or SNR model?
As we all know, there is a relationship between SINR or SNR and BER. Specifically, when SINR/SNR is higher, the BER is lower. And there are lots of work on modeling the complex SINR/SNR.
SNR
...
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3
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2
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299
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Signal noise cancelled by touching the leads
I have a pressure sensor that outputs 0.5V with a +/- 20 mV noise. I am trying to identify the root cause of the noise using an oscilloscope.
The noise occurs in waves of twice the mains frequency, ...
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3
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2
answers
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Ringing in OPamp OutPut
I am using this Differential In/Out Opamp circuit as ADC driver and to provide some gain(G=6.4).
The component values are R53,R52=100, C28, C27=1.1uF, R56= 1K, R57=open, R55,R54= 2K7, U6=OPA2211.
At ...
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Step by step calculation of noise factor does not match the overall system calculation
I know this is a very stupid question but I've been trying for a couple of days now to figure out what mistake I'm doing.
I have two cascaded blocks as following:
Block one is an amplifier with:
Gain (...
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3
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1
answer
487
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How to eliminate the noise of this circuit?
I've built the following circuit on a PCB with reference to a TI's solution.
I changed the gain of the INA to 10 and the gain of the A3 stage to 40. I also changed the cut-off frequency of the A4 ...
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1
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GPS - Noise Figure Analysis
I am trying to analyze all components in one home-made GPS receiver and I am stuck with figuring out how to determine Noise Figure at the mixer output.
See picture below:
If we are going from the ...
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1
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Does noise increase when using connectors with lower pitch?
I'm building an EEG circuit and as such there are approximately 128 channel leads. At the moment I'm just running standard wires but to improve space and neatness I'm going to print these on a flex ...
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2
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Is GNSS S/N equivalent to C/N?
I work in developing software that integrates with GPS and Galileo receivers. I've struggled for years with inconsistencies in documentation for the NMEA emitted by such receivers, and I've decided to ...
3
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1
answer
3k
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How do I find spectral purity?
How is spectral purity measured? or evaluated? I have this signal coming from a 10 MHz crystal oscillator. I know how to calculate the SNR, but how do I calculate the spectral purity? Is it also a ...
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3
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Opamp Input Noise Source?
Team, I have this basic opamp circuit:
However, I see a harmonics in input (VAC-IN, green) that's being amplified in the output (VAC-OUT, yellow):
This 'noise' is not present when signal generator ...
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2
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1
answer
673
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Noise can be Differential or Common!
I have a basic understanding on this topic but i still have some doubts, my text books says Differential means it will have impact on one of the 2 signal nodes. and Common will have a common impact on ...
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2
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2
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461
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Producing simulated thermal noise
I’m trying to simulate thermal (Johnson) noise. As I understand it, thermal noise follows a Gaussian distribution, power at the receiver is given by:
$$
P = 4kTB
$$
And the RMS voltage is given by:
$$
...
2
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3
answers
124
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Oscilloscope averaging and standard quantum limit
Oscilloscopes give a Vrms noise and have a noise floor, but if I average for a long time to infinity, am I at the standard quantum limit and does SNR keep improving with the sqrt(N averages) forever?
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SNR improvement from placing analog filter ahead of digital filter
We have designed a PCB containing a data collection circuit for a customer, and their external expert presents this "helpful suggestion":
Question about signal averaging vs. longer integration ...
- 3,010
2
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1
answer
901
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Potentiometer ADC noise varies based on position of wiper?
I have a potentiometer setup as a voltage divider like so, where the wiper of the potentiometer gets fed into my MCUs ADC Pin:
When I measure the noise of the incoming ADC signal, I get different ...
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1
answer
908
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What is the difference between SNR of a wideband system and the SNR for a narrowband system
I was reading Wireless Communications by Andrea Goldsmith in the book the author has stated that the Noise power for a wideband system with Bandwidth B is (B*N/2).
Could someone help me understand why ...
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2
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With regard to GPS signals, what is the significance of I-parts and Q-parts of Complex signal?
What is the significance of I-part & Q-part magnitudes and imbalances in the screenshot?
They are listed next to the red Complex signal diagram.
Imbalance of I-part: 4.7%
Imbalance of Q-part: 25....
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2
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1
answer
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Sonar single transducer element SNR vs array SNR
Background:
I'm taking a flexible learning unit on radar and sonar systems in a vocational college for an assoc. degree level course. The teacher has given us a reading assignment: "Chapter 15 ...
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2
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2k
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ENOB Calculations
I've been having a discussion with a colleague about ENOB (effective number of bits) calculations for DACs and ADCs. We both come across it from different directions (he being more analog, and me ...
- 1,713
2
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2
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650
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Amplitude Spectral Density from a Fast Fourier Transformation
I want to calculate the Noise-equivalent Power (NEP) of a photodetector.
Hereto, I have to measure the Amplitude Spectral Density (ASD) of the detector and divide the result by the Responsivity:
The ...
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2
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2
answers
307
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Noisy output on voltage reference and correct probing
I'm building a circuit that has a 2.5V Voltage reference for use on the internal ADC of a STM32F7 in 12 bit mode. As each bit corresponds to 610uV I'd like to have as little noise in the signal as ...
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2
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269
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How to eliminate the noise that is generated after the A\D conversion?
I have built a Ultrasonic range sensor using a ultrasonic (250ST/R160) speaker, which emits a 25kHz square wave with a Vpp of 12V for 1ms. The microphone (SPU0410LR5H-QB) is powered with 3.3V and its ...
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2
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493
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How are the original signal and the AM signal related?
Use the TIMS “Variable DC” module to generate a 1V DC signal.
Use the “Adder” module to add this DC signal to the message
signal generated in task 1 (this will produce the ...
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2
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1
answer
3k
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Difference between SINR SNR
I am bit confused between these two terms. I understand SINR is signal to interference+ noise ratio and SNR is signal to noise but isn't interference noise too? Then why have he segregated these two ...
2
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1
answer
63
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How to use my bits to transmit this photodiode signal in the most efficient way possible? [closed]
Suppose I have photodiode with a Dark Current of 5 pA and that using the NEP of that photodiode at some frequency \$\lambda\$ I determined that the smallest signal I could detect was of 1 pA.
First ...
