Questions tagged [signal-to-noise]

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32 views

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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63 views

Avoiding signal interference in a cable that carries video signal and sensor signal

I am using a 6 core shielded cable. In this 3 wires are used for a sensor and 3+1(shield) is used for a analog camera. All the cores take DC supply. Sensor(3 wires) (+)24 volt supply, (-)minus, ...
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19 views

How does electrical noise affects signal and distribution power?

What is electrical noise and mechanical noise How does it interfere with power? - signal power - Power distribution/ transmission
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23 views

How conventional DFE (Decision Feedback Equalizer) works?

There are a lot of variations of DFEs online. But I couldn't find a step by step explanation on how for example the 2-tap DFE works. Can you provide an explanation with a scheme ? I looked for some ...
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1answer
42 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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3answers
127 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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1answer
38 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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1answer
131 views

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, ...
2
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1answer
52 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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75 views

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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1answer
38 views

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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0answers
75 views

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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2answers
110 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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3answers
92 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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1answer
73 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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1answer
432 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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2answers
152 views

high frequency vs low frequency lock-in regarding signal to noise ratio

I understand that the lock-in technique came about in an effort to improve signal to noise ratio. There are lock-in amplifiers operating in high and low frequency regimes. In the context of signal ...
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0answers
40 views

Is this SNR change related to aliased common mode noise or some other phenomenon?

Below time series offset value of a force transducer amplifier which is sampled by a 16-bit single ended earth grounded data-acquisition board at 500Hz (red plot) and 12kHz (green plot). Before I was ...
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1answer
48 views

Index of frequency larger than power spectrum length

I am new in this community. So excuse me if it seems easy. I want to calculate the amplitude of a specific frequency in a signal. The frequency precision is (relevant question) $$ df = \frac{fs}{NP} $...
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3answers
91 views

Strange Frequency in Sensor Data

I've built a fairly simple Temperature logging device on an Arduino Mega 2560 R3. I'm using TMP36's, 12 of them in total to log the data. Each sensors VS and GND pins are connected to common rails and ...
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1answer
216 views

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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2answers
138 views

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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1answer
42 views

how to model AWGN for a Triangular waveform

If I want to generate some Additive White Gaussian Random Noise on top of my signal, how should I do it, if my waveform is triangular instead of being rectangular. Because I am sure I have to somehow ...
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1answer
521 views

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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4answers
762 views

How is “signal strength” characterized on a coaxial cable?

I've come across the Shannon-Hartley theorem, so I assume that a "signal" must have some notion of strength or "power" that can be referenced to some noise level (and whose power can be varied at the ...
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2answers
296 views

Reference signal choice for Lock-in Amplifier

How do you choose the reference frequency when using a Lock-in Amplifier? I want to measure the amount of lateral deflection of a laser reflected off of a surface that will be oscillating very ...
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1answer
50 views

Stability of delta sigma modulator with high frequency signal input

What happens to the high frequency part of a signal (in the region where the quantization noise is high) requantized with a delta sigma modulator, let's say with $$STF = 1$$ and $$NTF = (1-z^{-1})^N$$?...
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2answers
77 views

How to obtain maximal voltage transfer?

I have a 50-ohm source which is the output from a photodetector, and I'm using a digitizer card which has 50-ohm inputs, reducing the signal voltage by a factor of 2. The information I care about is ...
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2answers
1k views

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 ...
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2answers
57 views

How are higher dimensional sphere packings used in signal transmission?

How are higher dimensional sphere packings (HDSPs) related to the error-correcting codes used by cell phones, space probes and the Internet for signal communication through noisy channels? HDSPs ...
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2answers
125 views

3 dB Noise Figure

A noise figure of 3dB, translates to an equivalent noise temperature equal to the room temperature. What is the significance of this relation? Is there a physical interpretation for this?
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2answers
221 views

S/N Formula with probability

Hello I am looking for the S/N formula that incorporates the probability of catching the signal, and setting an arbitrary treshold level above which we detect the signal. I can't figure out the ...
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2answers
137 views

Is the use of a Lock In with a signal generator appropriate and practicable?

I want to generate a 5 kHz microwave pulse to induce a sample signal. This microwave pulse has an underlying microwave frequency of 2 GHz. In order to investigate very tiny signals, which should arise ...
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2answers
98 views

Noise figure of Microwave radio receiver

I always wondered why ADC is not considered for noise figure measurement in receiver chain? Do ADCs will not have much impact on noise figure in signal processing? How to derive a Noise figure spec ...
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2answers
246 views

Sending PWM signals over wire

I'm sending two complementary PWM signals from a control board to a separate power board via a ribbon cable (along with some other signals, 20cm or so). The PWM signals control a MOSFET driver on the ...
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1answer
339 views

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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3answers
112 views

Optimizing dynamic range for acquisition of noisy signal

Is there a good rule of thumb for setting the gain of a noisy signal before digitization? Say I have a 16-bit ADC with a ±1V range; to what level should I amplify the noise floor of my signal relative ...
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4answers
325 views

Confusion with the relation between SNR, voltage divider and amplifier concepts

Imagine you have an input signal s(t). And the signal of course has some noise n(t). So lets say the SNR value is x. Now if we attenuate this signal by a voltage divider by 100 lets say, will the SNR ...
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3answers
205 views

Limiting Current interference in Photomultiplier Amplifier Circuit

I've been working on a circuit for a while now. It's a circuit consisting of 4 Silicon Photomultipliers, MicroFJ-60035-TSV, in parallel all going into an op amp circuit. I posted questions about it ...
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1answer
1k views

How to measure Noise Figure of LNA

I know how to calculate Noise figure of an amplifier on the paper but how can measure Noise figure of a LNA in real world? Our lab doesn't have a fancy Noise figure meter but I can readily access to ...
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2answers
644 views

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 ...
1
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1answer
260 views

How can I filter out sunlight on a solar panel so that I can read a signal from a red laser?

So right now I have a small solar panel (4" by 4") and a red laser. I'm trying to design a laser tag system that doesn't follow the way that traditional laser tag is done. I want to be able to shoot a ...
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3answers
492 views

Microphone saturation avoiding desired signal from being detected

I'm trying to detect a known signal under heavy interference. I'm working with 2 smartphones and an interfering speaker. I'm sending a signal from one smartphone speaker to the other smartphone ...
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7answers
1k views

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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4answers
3k views

How to properly clean up a noisy signal with a capacitor

I'm reading a pulse from a camera back to a raspberry pi and the noisy signal is causing the gpio pin to read too many inputs. My signal is 3.3v. I'm currently using a 1uf Cap to try to clean up the ...
1
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1answer
347 views

How can a USB cable extender boost the signal without an external power source?

I've been searching online for a USB Cable extender for a rather long distance (let's say 10 meters). I'm familiar with the notion that the longer the cable, the weaker the signal might get, more ...
1
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2answers
82 views

How does using double antennas (one with delay) and adding their output help the SNR?

This is a question our professor asked us to think about. Suppose that we have a communication system with no interference with no channel imperfection but Ergodic AWGN noise. We use two antennas with ...
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1answer
114 views

Adding Controlled Noise to Signal

I want to add noise to some signal. I have the option to add the noise via the software API of the system. But I also have the option to add the noise in the hardware circuit itself so there is no ...
3
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1answer
90 views

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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2answers
277 views

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 ...