# Questions tagged [snr]

Signal-to-Noise Ratio

68 questions
31 views

### Power spectral density PSD of optical waveform given in power [mW]

Sanity checking- if I'm given the optical waveform in time on an optical oscilloscope given in units of uWatts (power) already, and I need to do a fft to get the power spectral density, I don't need ...
35 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 ...
86 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 ...
28 views

I have a question about a problem in a textbook I can't exactly solve. It goes as follow: Given a message m(t) as input to a DM system $$m(t) = 3cos(890\pi t) - 0.7sin(1000\sqrt{3}t)$$ Determine ...
91 views

### How to improve this microphone phantom power supply to have better SNR?

I built this power supply for my Schoeps CMT30F vintage microphones: It works, but it's not the best I can expect in terms of SNR. What would do you to ensure the SNR is the best possible? Use 0,1% ...
50 views

### Derive required carrier to noise or signal to noise from receiver sensitivity on FM receiver

Can I extrapolate the required C/N based on reported receiver sensitivity? I'm plotting coverage for a repeated radio system for handheld radios. The system is analog, FM narrow band. I've ...
47 views

### SNR wall definition

I want to ask you if my understanding of the definition of the so called "SNR wall" is correct and complete. The SNR wall phenomenon is described here and here. If one has further information that ...
22 views

### M-PSK modulation

From what I read the sigma value for 4 psk modulation is sigma=sqrt[1/(2*SNR_LINEAR)] But when you add the average energy of 4 psk which is given by [1+0i;0+1i;-1+0i;0-1i] this gives you 0 so how ...
76 views

### Why is the dB of the FFT plots exceeding 96dB for these signals sampled by an 16 bit ADC

There is a 16-bit data acquisition board and below is the recording of 120 seconds of voltage input at 500Hz sampling rate. The blue plot corresponds to the input voltage Vin and the green plot output ...
69 views

### Does SNR improve at higher sampling rates for a low pass filtered signal?

Let's say we want to extract 1Hz signal from a noisy signal by using a LPF. And assume we have sampled it with 100Hz sampling rate. If we would have sampled it with 1kHz sampling rate and use the ...
109 views

### Effects of increasing current on external noise and SNR for analog transmission

This is a conceptual question about long analog signal transmission exposed to capacitive coupling and EMI noise as shown in below figures: simulate this circuit – Schematic created using ...
1k views

### How to measure SNR with an oscilloscope

Suppose I have a signal that consists of a sine plus noise. Is it possible to measure the SNR with an oscilloscope? Is the following procedure correct? Check the noise floor in the FFT mode of the ...
49 views

### Can I measure the voltage noise with True RMS function

I have a measurement setup with which I want to measure high voltages. Now I want to evaluate the noise this setup produces (preferably in V/sqrt(Hz)). I short circuited the input and I am now ...
484 views

### How is SNR defined in a DAC?

In the datasheet of the dsPIC33FJ128GP802 it is said that the SNR of the 16 bit audio DAC module is 61 dB. What does this mean? How much RMS white noise voltage should I hope to see? I know the SNR ...
117 views

### How to calculate noise power (dBm) of a photodiode?

I want to check the thermal noise spectrum of a photodiode (PD) at different frequency response but I do not know how to calculate it. Below graph is an example which shows noise power (dBm) as a ...
46 views

### SNR when calculating noise

I am trying to solve a few example questions relating to input voltage and input noise for the following questions. and I understand that I need to calculate the maximum noise voltage acceptable ...
37 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 ...
71 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 ...
276 views

### How do you find the resolution and sampling rate needed for a certain signal to noise ratio of an analog to digital converter?

For example, I want to convert an analog voltage signal to digital. I want to have a signal to noise ratio of at least 50,000 without aliasing. What sampling rate and resolution could I use to achieve ...
95 views

### Audio ADC voltage level SNR question

I keep looking for Audio specific ADCs and the majority of these devices work at low voltages on the analog circuitry (5V for example). Lets say we want to process an higher voltage audio input ...
60 views

### Signal Noise Ratio Computation

Say I have a signal that $y(t) = s(t) + n(t)$ where $s(t)$ is the desired signal and $n(t)$ is the noise signal. I understand that if the mean value is $0$, the Signal-Noise-Ratio can be ...
40 views

### SNR of SIMO model

Here is my question regarding SNR of a SIMO model (one transmitter antenna and K receiver antennas): $$\vec{y}_{K\times 1}=\vec{h}_{K\times 1}x+\vec{n}_{K\times 1}$$ In a Matlab simulation, if say, ...
151 views

### Trying to determine the SNR of a dirty signal

I have a dirty sine wave at about 8 Hz, and I want to figure out the SNR using MATLAB. Would a reasonable approach to answering this question be to generate a clean 8 Hz sine wave in MATLAB and then ...
587 views

### SNR and Attenuation Question

Hello, I have a question above from random material and tried to solve it. Here, I assume signal power to be S1(dB) and noise power to be N1(dB) at input, and S2(dB) and N2(dB) at output. So below ...
2k views

### How does a preamplifier improve the Signal-to-Noise Ratio (SNR)?

I'm trying to understand how a preamplifier works. Is the noise not amplified the same amount as the signal? If so, how is that done in the preamplifier?
523 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 ...
117 views

### sigma delta SNR

As you know, Sigma-Delta Modulator as the core of sigma-delta ADCs defines the total SNR. I am simulating a very simple code for first order delta-sigma modulator. According to text books, the SNR of ...
380 views

### Photo diode TIA

here i have designed a TIA circuit with the suitable values for the feedback resistance and feedback capacitance and using the FDS100, to achieve a bandwidth around 43 MHz, the simulation is running ...
2k views

### Why is a lower Noise Figure considered better than a higher Noise Figure?

I'm trying to understand why a smaller Noise Figure is supposed to be better. The conventional definition for N.F. is the ratio of SNR(in) to ...
46 views

### SNR of simulated signal (no background)

I have the simulated signal of an MRI measurement distorted with Gaussian noise of mean value = mean signal magnitude and sd = 1% of mean signal magnitude. How can I calculate the SNR? I think that ...
78 views

### Problem about Nyquest signalling theorem?

A sinusoidal signal with amplitude 20 V and bandwidth 35 kHz is sampled at 2.5 times its Nyquist rate and then quantized using a 128-level quantizer. Determine: i) The resulting data bit rate? The ...
178 views

### Analog Multiplexer as the first stage of DAQ system?

Recently I am designing a Data Acquisition system which utilizes FPGAs and ADCs. As my project needs to have a good balance between price, performance and quality, I have looked into the market to ...
235 views

### RF over sampling to increase SNR

Using a 32MHz pic processor, and over sampling the demodulated analog output of an RF receiver (instead of the data slicer output) is it possible to use averaging to reduce increase the SNR of the ...
475 views

### Smartphone microphone frequency response, ADC and SNR

I'm trying to find on the web if there's an example of smartphone that records with low quality (which introduces lot of background noise) and an example of phone that records with good quality, maybe ...
70 views

### How to evaluate quality of signal?

guys. I'm trying to evalute received signals from a transceiver. I'm a rookie in wireless communication. So I hope that you guys can help me out. I want to make a threshold of received signal so that ...
128 views

### I'm confused about how to calculate noise for an SNR? [closed]

My Rx radio is getting -60 dBm but I don't know how to find the noise. My thermal noise is on the order of E-12 so it barely affects my SNR. Where does noise come from and how can I calculate it?
98 views

### Approximation for high SNR

In Slide 6 of this PDF, it says that the performance of binary signaling is as follows: I can understand the approximation for high SNR in the incoherent FSK and DPSK case, but how do we get the ...
150 views

### SNR definition in SIMO system

Consider a SIMO (1 transmitter - several receivers) system in which The receiver antennas are used to obtain space diversity and we have a multipath fading channel between transmitter and each ...
968 views

### SNR in distance estimation?

I'm working on a project where I locate an object using TDOA (Time Difference of Arrival) plus RSSI with trilateration method. The object send a message to antennas near it. The problem is I want to ...
301 views

### 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 ...
195 views

### How can Nyquist Frequency increase SNR?

I am busy with Dynamic Range of an ADC including Programmable Gain Atmplifier. I try to calculate maximum Dynamic range level of my measurement system. How can i calculate Dynamic range? I have read ...
279 views

### Maximum achievable SNR (SNR before LNA)

I am trying to understand the concept of noise figure and the best achievable SNR. The noise figure is a measure how much a device degrades the SNR. Say I have a receiver with a NF of 16dB, then the ...
251 views

### Noise Matching transformer [closed]

I'd like to use a transformer to improve the performance of our SR5184 preamp. The signal recovery SR5184 is an ultra low noise preamplifier. It has 0.8 nV/ √Hz input noise and a bandwidth of 0.5 Hz -...
1k views

### How to measure SNR of a telephone Line? What is the device (without using router)? [closed]

I'm a beginner level eng student. I've just find this place and I need your help. I need to create SNR detector without using a router login. So, Is there any small device to measure SNR by ...
153 views

### misunderstanding from definition of SNR

We know that SNR is defined as "power" of the transmitted signal to the "power" of the noise. In practice we transmit time limited signals (for simplicity consider the case that there is only one ...
79 views

### Noise vs Signal

All, I have created a photo-diode amplifier(2 stage) which allows me to set a gain from 2 to 551 (v/v) [4.6 to ~55dB] in 64 steps. The gain is achieved using pre-calculated resistance to provide non-...
229 views

### 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 ...
771 views

### Analog vs Digital attenuation for an ADC

I'm designing a digital parametric EQ that will go in front of a high gain guitar amplifier. I want to have the option to boost signals up to 12dB. I plan on implementing this either by attenuating ...
5k views

### How to calculate the SQNR of the PCM system in dB?

Assume that the input signal S(t) is sinusoidal with amplitude A and quantized to R number of binary bits, how can I calculate the SQNR of the PCM system in dB? I know that the output signal-to-...
2k views

### Calculating SNR after lowpass filtering

I am currently working with a sinusoidal signal buried in noise. I filter the signal with a low-pass filter of which I know the transfer function. How can I calculate the SNR after the filtering ...