Questions tagged [signal-to-noise]

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How to determine noise power and SNR from extinction ratio?

I have a pulse train signal with infinite extinction ratio (ER). I want to add a white gaussian noise to my signal to get ER=15 (dB). I know that ER=P1/P0, i.e., the power level with the light source ...
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ATmega analog comparator generates spurious interrupts

I'm experimenting with the comparator inside a ATmega328 to see if it can be used for zero detection of a DC 2.5V superimposed AC signal monitored on one of the ADC inputs. I use the code as shown ...
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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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Acceptable SNR for a Sound Level Meter

I'm designing a low power (<150mW) sound level meter (SLM) using a 24bit ADC (preliminarily using the LTC2512-24). This is for audible frequency range signals only (20Hz - 20kHz). I'm focused on ...
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Can an LNA noise figure be normalized to dBm to estimate the minimum detectable signal?

If a device claims a noise figure of 0.3 dB NF such as the Qorvo QPL9547, can you calculate the dBm value of a signal that is at the noise floor (ie, a barely detectable signal)? Otherwise stated: I ...
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Signal to Noise Ratio Vs Signal to Distortion Ratio

I am a bit new to this field and I was reviewing some speech enhancement papers. These two terms keep popping up every once in a while so I was very confused as to what the difference between these ...
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1 answer
182 views

Estimating shot noise - what's the origin?

If I have some photon detector, say a CCD, how do I estimate the error introduced by shot noise correctly? Typically, sources found on the internet say that the shot noise is the square root of the ...
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Consider Noise in Link Budgets

I want to verify the range of my RF-system for a university project. I use two transceivers (Datasheet) and one power amplifier on the transmit side (Datasheet). The target range is 120 km over which ...
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144 views

Noise Figure of an Attenuator

it is known that the noise figure of an attenuator is equal to its attenuation coefficient L. A proof of this statement is provided here. Basically, it uses the formula (Reference): $$F = 1 + \frac{...
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need help with small load cell and ADC

I am working on a project where I should be able to measure as low as 1mg load change. The acceptable error margin would be 0.1 mg. I am planning to use load cell with total capacity less than 10g ...
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4 answers
341 views

Build a Radiated EMI Generator

I'm building a radiated noise generator. My intention is to expose my developed equipment to electromagnetic noise. I want to check the behavior of the equipment in noisy situations. So I want to ...
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Can I connect GNDD with GND to get stable result?

I am using JY-S60 Signal conditioner (SC) (click here to see datasheet, giving amazon link, could not find specific link for datasheet) with small load cell click to see load cell datasheet. I have ...
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2 votes
2 answers
188 views

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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S/N ratio or distortion analyzer

I'm having trouble finding an affordable low bandwidth analyzer solution for measuring audio spectrum performance (20KHz and below). Does anyone have a suggestion for buying (new / used) or building ...
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1 answer
296 views

Noise figure calculation in LTspice

I am a newbie in LTspice so the question can be seemed to be bit stupid, but I have build an LNA and now I want to calculate the noise figure of the system. I have run the .noise statement to ...
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1 answer
718 views

What is the derivation for Shannon Hartley theorem?

I know by Hartley's theorem that information is proportional to bandwidth and time. The capacity corresponds to information and bandwidth is there. I don't get how the logarithmic part corresponds to ...
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2 answers
197 views

In noise voltage equivalent circuit, why are the source and load resistances equal?

Yes I am aware of the maximum power transfer theorem. I don't get though what the lesson meant, especially by worst condition.
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3 votes
2 answers
80 views

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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1 answer
116 views

Noise equivalent power of thermopile sensor?

I am working on the characterisation of thermopile sensor and stuck in determining the NEP of the sensor. My thermopile sensor with AD8630 amplifier receives IR radiation coming from the blackbody at ...
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How exactly does the low-pass filtering in a lock-in amplifier correspond to a time-averaging?

In this white paper of Zurich instruments two ways of explaining a lock-in amplifier are shown: low-pass filtering and time-averaging. Whereas the explanation with time-averaging can easily be done ...
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1 answer
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Advice on Noise in Square Input Signal

I am reading the following signal from an open drain output, and trying to read the signal frequency. However, I am getting short spikes in the wave as seen below, and this is messing with the reading ...
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Maximizing signal to noise ratio for very small radiation detector

I have a very small radiation detector that outputs signal of small amplitude. Requires preamplification before going to an actual amplifier. When constructing the system prior to the preamp, would I ...
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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 ...
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2 votes
2 answers
127 views

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: $$ ...
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2 answers
107 views

How to calculate noise voltage after amplification?

I'm simulating the thermal noise experienced by some instrument, outputted as a voltage vs time plot. To calculate the "power" of this noise, I'm using: P = 4kTB (k = Boltzmann's constant, T ...
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How to calculate thermal noise contributed by an LNA?

I've written a thermal noise simulation for a piece of equipment which produces the oscilloscope trace one would expect to see coming out of the instrument. Now, I'd like to take into consideration ...
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2 answers
171 views

How to plot thermal noise in the time domain?

The power of this thermal noise is given by: P = 4kT (k = Boltzmann’s constant, T = temperature (Kelvins)) And, thus, the voltage by: V^2 / R = 4kT (R = resistance) Finally, we must take into account ...
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1 vote
3 answers
77 views

Do parallel LNAs at 90-degrees to eachother reduce the noise floor more than side-by-side?

Wiring amplifiers in parallel in a summing configuration improves the signal to noise ratio because amplifier noise in each LNA is uncorrulated. However, external noise sources will still be a factor ...
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How does wiring two LNAs in parallel affect charactaristic impedance?

It appears that wiring amplifiers in parallel improves the signal to noise ratio. I thought I would experiment with two SAV-541+ LNAs in parallel and see how they perform: How does wiring an LNA in ...
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6 votes
1 answer
221 views

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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3 answers
95 views

Signal to noise in relationship with limit of detection and/or signal strength

I wonder about the following: The limit of detection is given as being 3 sigma of the blank peak away from the blank signal (which is noise finally, I think?). What struggles me is: In my head this is ...
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Regarding signal to noise ratio

I had set up multiple receivers and I was recording the same signal on all of them. I then stacked all of these signals. I have read that to improve the signal to noise ratio, mean and median of this ...
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2 votes
2 answers
120 views

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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-1 votes
1 answer
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Would submerging a 100% waterproof hotspot device increase network connectivity?

I have this portable hotspot device (9cm*6cm*1cm*) in which I insert a simcard and keep it within 10m when I am using it. Let us consider that it is water cannot damage it even if I submerge it. Would ...
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6 votes
5 answers
1k views

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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1 answer
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Noise Floor of ADC using PWELCH

While using MATLAB's Pwelch function, I am not able to match the noise floor of the "Modelled" ADC to (Delta)^2/6 {1 sided Spectrum}. ...
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2 answers
114 views

What is the math behind high FM frequency components being more noise prone? [closed]

what is the math behind the phenomena that higher frequencies are more prone to noise? The use of pre-emphasis to boost the higher frequency components to get a better S/N ratio. Can you provide ...
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1 vote
1 answer
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Problem in deriving Noise Figure for Cascaded systems

I am trying to derive Noise Figure of Cascaded System. I am making some conceptual mistake somewhere in derivation and getting wrong answer. Can any one please help me figure out where I am going ...
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1 answer
136 views

SQNR and Dynamic Range

An audio tone \$Acos(\omega t + \theta)\$ undergoes uniform quantization by a quantizer that has the average quantization noise power \$q^2/6\$ joules, where \$q\$ is the quantization step size. If ...
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3 answers
604 views

Harmonic detection using lock-in amplifier

Can a third harmonic of a signal be detected using a lock-in amplifier under the same parameters fixed for collecting the fundamental or the parameters needs to be adjusted.Here by parameters I mean ...
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0 votes
1 answer
46 views

Communication in presence of noise: Why is the number of distinguishable amplitudes K*sqrt((S+N)/N)

In section VII: The Capacity of a channel in the presence of white thermal noise in his 1949 paper Communication in the presence of noise, C.E.Shannon says, that for a signal with average power P, ...
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1 answer
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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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2 votes
1 answer
60 views

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 ...
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Estimate minimum detectable light pulse in a photodiode (5 ms, 44 kHz modulated)?

I'll use an IR LED modulated at 44 kHz to illuminate particles in air or water, and will use a silicon photodiode to detect weak pulses of scattered light as they pass through the LED's collimated ...
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1 answer
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SNM (Static Noise Margin) and DNM (Dynamic Noise Margin) confusion in digital circuits

I've found in several sites that SNM is the min between NMH and NML where NMH=VOHmin-VIHmin and NML=VILmax -VOLmax But this paper really confuses me, because it uses the same graphics and apparently ...
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1 vote
0 answers
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Determining required signal SNR (beat signal from FMCW RADAR)

I'm trying to determine the SNR required for signal outcoming from FMCW Radar. This is the chain: signal will created by "24 GHz VCO and PGA with 2-Channel PA Output" by triangle shape frequency ...
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1 vote
2 answers
122 views

Maximum rate Shanon Hartley

i am reading computer networks and i am trying to solve an excercise. the excercise is What is the theoretically the maximum rate at which data can be transmitted to a 4000Hz bandwidth ...
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2 votes
3 answers
112 views

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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1 answer
101 views

noise of high speed serial link

I have an ADC module. The board contains sensitive (10-100MHz) analogue parts and a high speed serial link (Aurora). The link uses scrambling algorithm, and I can choose the bit-rate. (I have much ...
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1 answer
1k views

Bandwidth-Noise-SNR relationship

Let’s say we have the noise figure F of a system of devices. We also have the bandwidth improvement coefficient ( as defined by my teacher ) $$BI=10log(\frac{B_{in}}{B_{out}})$$ where B1 is the ...
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