Questions tagged [analog-to-digital]

An analog-to-digital converter (ADC, A/D, or A-to-D) is a system that converts an analog signal into a digital signal.

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Electric Bass with RJ45 Digital Output

I'm working on a project bass guitar with individual outputs per string using Nu pickups from Cycfi Research: https://www.cycfi.com/ The common sense approach is to simply take their circular ...
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81 views

Quantization error of SAR-ADCs

My question is related to the quantization error and the functionality of SAR-ADCs. In general, the quantization error of an ADC is defined as +-0.5LSB. If this concept is correct a voltage that ...
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61 views

I/Q sampling with just one ADC

Usually I/Q sampling is performed on two signals with a 90° phase shift using separate ADCs. Suppose I have only a single (fast) ADC available to perform I/Q sampling, which approaches do exist? Is ...
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48 views

transfer function of a sampler in the s domain

I would like to modelize my whole system into the S-domain. This is a mixed system, there a numerical part (corrector, ADC, DAC) and an analogic part (plant transfer function, sensors, etc...). I know ...
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42 views

Increasing ADC output accuracy

Say we have a 12-bit ADC with 30 MHz sampling frequency. I want to perform several DSP operations on output digital signal so that resulting signal would have increased accuracy to 14 bits and output ...
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140 views

Oversampling in quantization

Q: It is said that "to maintain the same quality in the two cases, we require that the power spectral densities remain the same". Why is this a measure of the same quality? Why is not the ...
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66 views

Condition for aliasing

Which one of the following is the condition of aliasing? (a) Tails of the replicas enter into the Nyquist interval (b) The tails of the replicas enter into the Nyquist interval and add to the ...
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1answer
49 views

Timbre vs sound via oscilloscope

My understanding is that a distinct sound will generate waves of identical amplitude and frequency, but that most things (such as people's voices, music intsruments, etc) produce multiple distinct &...
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204 views

Using oversampling to increase resolution of a DC-signal as input

Currently I'm working on a project which uses oversampling to increase the resolution of a 12 bit ADC to a maximum of 16 bits. My goal is to fully understand the theory behind oversampling and why it ...
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40 views

Sampling interval $T$ as a multiplier in digital processing of a continuous-time signals

[from: Discrete-Time Signal Processing, Oppenheim and Schafer, p.224] Q: Why do we have $T$ as multiplier in $TY_a(j\Omega)$ in Eq.155?
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150 views

Is this an error in Oppenheim and Schafer's Discrete-Time Signal Processing?

In Discrete-Time Signal Processing by Alan V. Oppenheim and Ronald W. Schafer (3rd Ed.), in Figure 4.47 the input of D/A converter is $\hat{y}[n]$ but later in Figure 4.64 the input of D/A converter ...
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Why do we need DFT when we already have DTFT?

We already have DTFT so why do we need DFT? Please don't write DTFT is used for discrete, aperiodic signal which transfers in the frequency domain to periodic and continuous, but in DFT is discrete ...
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How can I do a validity check of an FFT

The aim is to identify problems in an ADC FFT simulation in an early phase of the simulation using the output bitstream of the ADC. The reason is to avoid long simulation times while using wrong data. ...
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Measuring the frequency of the Analog input signal of an ADC, which is operated by Raspberry PI

I'm building a monitoring package for a sensor via a raspberry PI and an ADC, which reads the analog signal (for the moment from a DC power supply instead the real sensor) and transfer it to my ...
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1answer
46 views

Understanding this Hanning Window implemented in microcontroller

I'm trying to calculate RMS of an AC signal which input frequency may vary from 40 to 70 Hz. I would like to use a window function because it accounts for frequency variations and also my ADC sampling ...
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22 views

Response time of residual current device and sampling times

The table below is from this document: Schneider RCD When the maximum response of the device is 40 mS, does it measure current doing RMS or peak detection? The document does not explicitly say it. ...
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34 views

Output signal is being attenuated after the Biquad filter direct Form 1, why?

Thought this would deserve a separate post on its own. What's going on is that I finally got my low pass digital filter working on the STM32H753ZI using the PMODI2S2 peripheral and I noticed the ...
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174 views

DSP low pass filter (IIR) no longer works when changed to a new MCU

Having troubles understanding why a DSP low pass filter was that working on the M4 is no longer working on an M7. I recently switched over to a STM32H753ZI from a STM32L432KC. In addition to switching ...
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580 views

Increasing SNR and Dynamic Range using Oversampling

How much gain in dynamic range and SNR can be expected if we are to oversample a signal with fixed analog input bandwidth. For Example if I have a analog filter at the input which limits the bandwidth ...
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1answer
40 views

How to modify zeros and poles in a delta-sigma modulator loop?

In this specific case, I am modeling a delta-sigma analog-to-digital converter with a basic loop in which the output $V$ is fed back with unity gain to be subtracted from the previously sampled input $...
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34 views

OFDM Signal Recovery with DAC & ADC

I have implemented 256-QAM based OFDM design on FPGA. The data flow is as follows - QAM -> Hermitian Symmetry -> IFFT -> Pilot Insertion -> Cyclic Prefix I have done Hermitian Symmetry ...
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3answers
130 views

Downsampling vs. ADC with lower Sample-Rate

I would like to know in general where the advantages and disadvantages are: Downsampling of a high sampled continuous analog signal in FPGA or µC and Direct use of a lower sampling rate, i.e. using ...
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23 views

How to calculate Integral Non Linearity (INL) the direct way

In the situation bellow we have a 3bit Analog to Digital Converter (ADC). where avarage the LSB from the non ideal system is I want to calculate the Integral Non Linearity (INL) purely from the ...
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FSK technique to superpose the digital communication on top of 4–20 mA signals

I start a working with HART devices and I really try to understand how digital data is transferred trough 4-20ma current loop. I start read this article: https://instrumentationtools.com/hart-...
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79 views

minimum oversampling factor for D/A converter

Consider a D/A converter for audio signals consisiting of a zero-order-hold interpolator followed by a continuous-time lowpass filter with positive passband between 0 and 20KHz and stopband starting ...
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88 views

D/A converter with

I am trying to figure out how to consider digital-to-analog conversion and how to consider oversampling based on a course I am taking online and figuring out the logic behind this. Unfortunately there ...
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29 views

μ-law compression technique

In μ-law compression formula i have always seen that the value of Xmax and Ymax is always same but can they be different?
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193 views

DC bias from ADC in frequency detection scenarios

In real-world applications where a frequency or multiple frequencies need to be detected from a digital signal that comes from an analog-to-digital converter (ADC), what are the typical 0 Hz (direct ...
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14 views

Snapshot of a signal

I need to understand what a snapshot of a signal is. Suppose I have a signal of duration, say, 10 microseconds from multiple channels and that the ADC samples every 20 nanoseconds from each channel. ...
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35 views

Do we have to insert the DC null in OFDM when using RF direct sampling ADC architecture?

Generally, DC Nulls are added in OFDM because zero-IF receivers don't pass the DC component. But what if I use an RF direct sampling architecture? Will there be DC offset? If not, then is it okay not ...
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1answer
55 views

Multisampling of an ADC channel in a PWM cycle in TI C2000

I want to sample an ADC channel multiple times in one PWM cycle. I can trig any ADC channel in anywhere in my PWM timer counter now. But I want to trig and sample same channel in many times within a ...
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1answer
62 views

Digitalization of a signal

Suppose I have an analog signal I want to transmit. After sampling and quantization, I can map the samples to bits. So now I have a bit stream that represents the original analog signal. My questions ...
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24 views

Resources on multiplexer and demultiplexer?

If I search multiplexer in Google and start reading, I find sources that describe a multiplexer as a device that selects between several analog or digital signals, then outputs a single signal. For ...
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Threshold Estimation from a Linear FM Pulse Position Modulated signal

I have a signal chain to detect multi channel LFM (Linear Fm - Hann window being applied as shaping filter for the pulses) pulses as shown in picture below. (Numbers in the picture is in Hz., for ...
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136 views

Are there analog re-configurable filters?

I know that we can build a chip (or circuit) or use FPGA to have re-configurable digital filters. But how about analog filters, can we have re-configurable analog filters? thanks
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29 views

synchronize adcs with neuronal network

if i have two adcs(analog to digital converters) sampling a signal. Is it possible to synchronize the two adcs with deep learning? as far as i know, with super-resolution on image processing it is the ...
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70 views

Sample and Hold Circuit at Digital to Analog Converters

Does DACs contain sample-and-hold circuits? I am a bit confused thanks
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1answer
38 views

Aperture Jitter in Digital to Analog Converters

I have noticed in the literature that there is an internally induced timing jitter inside Analog to digital converters called (aperture jitter). It is caused by the sample-and-hold circuit of the ADC. ...
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how to do smoothing a linear noise adc signal to a exponencial curve to increase and logarithmic to decrease

I am studying methods of signal smoothing obtained in an Analog Digital converter that is operated by a common potentiometer that generates a certain noise, such potentiometer is linear and I cannot ...
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what is the DNL of flash converter

i have a flash ADC converter with 1V vref and idial ressistors but in the comparator i have standart deviation of 3mV. how do i calculate from the the standart deviation of the whole device(DNL INL)? ...
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32 views

Reconstruction of Contiuous - Time Signals

In terms of analog signals, we can represent digital signal as : $$ x[n] \triangleq x_{a}(nT) = \int_{-\infty}^{\infty}X_{a}(f) \, e^{j2\pi f nT} \ \mathrm{d}f $$ While if we focused on the integral ...
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How to Compensate for Frequency Offset in single carrier transmission Using Coarse and Fine Compensation?

How to compensate for the frequency offset of a PAM, PSK, or QAM signal when we are using single carrier transmission, I am looking for algorithms, explanations to be able to carry out the ...
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1answer
27 views

What does an ADC DNL specification mean, exactly?

I'm looking at the differential non-linearity specification for an Analog-Digital converter. The spec sheet claims that the DNL ranges from -1LSB to +1LSB, with a typical value of $\pm$0.6LSB. What ...
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88 views

DAC and ADC architecture in SDRs

What are the DAC and ADC architectures in SDRs for inphase and quadrature phase channels? Do we have separate ADC and DAC for each channel or there is some clever way that they are multiplexed to ...
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1answer
71 views

ZOH DAC amplitude formula testing

We have an expression shown in red bellow for non ideal DAC ZOH,which links the sampling frequency to the amplitude loss of the input signal. I took $f_b=1kHz$ and $f_{noise}=4kHz$ $f_{in}=f_b+f_{...
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183 views

Calculating dBFS for I/Q

I'm trying to figure out how to calculate the dBFS for a complex input. I have an AD9361 part which has a 16-bit A/D and I believe outputs I and Q samples. Now I know you can calculate the dBFS for a ...
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1answer
48 views

How to add a particular noise on a signal?

I have a simple ADC model (an input signal == sampled signal ). The adc should be modelled as with following values: 1.5 V (peak to peak).. meaning --> +1.5 V --> 0 dBFS ... how to do this ? The ...
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393 views

Difference between formula of SNR and SQNR?

Is there any difference between formula/expressionsof SNR and SQNR? where SNR is Signal to noise ratio and SQNR is signal to quantization noise . The following DSP SE question shows both SNR and SQNR ...
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1k views

How we can quantize a sampled signal in MATLAB?

I have a continuous time signal $x(t)=\sin(2πft)$ where $0 \leq t \leq 3$. I want to sample the continuous time signal and then quantize that sampled signal and then plot both sampled and quantized ...
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126 views

confusion sampling vs quantization?

while converting analog signal to digital equivalent,we have a process that is called analog to digital conversion and it has two main steps/stages sampling and quantization? I am confused whether y ...