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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1answer
46 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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66 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
294 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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31 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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32 views

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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105 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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2answers
124 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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1answer
35 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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1answer
220 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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1answer
52 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
115 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
66 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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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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1answer
150 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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30 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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1answer
255 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
54 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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1answer
33 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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2answers
242 views

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
28 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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2answers
142 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
95 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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1answer
375 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
67 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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1answer
759 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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1answer
2k 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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3answers
270 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 ...
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Understanding shift in Q values?

Can any one help me understand why there is a shift in Q values? It seems there is a DC offset/bias. How do I remove it or set it accordingly to make it equal to the I values/waveform? I am using a ...
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1answer
156 views

ADC sampling rate implications Matlab/Simulink M-PSK modulation

I am trying to find a way to evaluate what would be the minimum sampling rate used in a modulated waveform using matlab / Simulink. The real scenario would be let say a M-PSK waveform of Y bandwidth ...
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1answer
261 views

Is there a relation between the dead zone of sigma delta modulator and filter order?

This question refers to the link https://pure.tue.nl/ws/portalfiles/portal/1546321/521243.pdf. In chapter 4 it discusses the topic of dead zone, which appears in the delta sigma modulator. Dead zone ...
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91 views

Nyquist sampling theorem / Nyquist - Shannon theorem evaluation over M-PSK

I am trying to simulate an M-PSK Tx-Rx System on Simulink and analyse what the effect of sampling rate reduction would have on it. More, particular I am trying to prove what Nyquist sampling theorem ...
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1answer
74 views

Sample & Hold: Estimate jitter delay of an ADC

I've got a question regarding the effects of sample and hold. My input signal is $x$, and my output signal $x_{SH}$. The error between the signals is $e_{SH} = x_{SH}-x$. The sampling frequency is ...
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1answer
259 views

Conversion from counts to dB

I have a sound signal, recorded by a hydrophone, which units are counts. I would like to convert the counts into dB re uPa (Decibels relative to microPascals), is that possible?
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1answer
211 views

DC Spur in DAC output

I have a design in which a signal from ADC is filtered and then played by DAC. In FPGA the real signal is converted to quadrature using DDS with 70 MHz frequency. After filtering, the baseband signal ...
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2answers
1k views

How to adjust receiver gains to avoid saturation and quantization noise to optimise post digital processing?

I am using a Hack RF One as SDR and the software GNU Radio to receive and process signals emitted from a drone. Given that the drone is moving and is emitting signals from a wide zone, received signal ...
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1answer
89 views

Does FFT magnitude of recorded sound depends on the bit depth used?

Based on some reading, here's my understanding of how sound recording works: Microphone outputs a voltage based on sound pressure. The microphone voltage is amplified and the amplified voltage goes ...
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2answers
2k views

Faster way to find the quantization level of a sample

Given a sequence of real numbers that represent a sound signal i.e [1.8, 2.2, 2.2, 1.9, -1.5, -0.7], we must quantize this sequence by dividing the range [-4, 4] to 32 equal parts. If we had to do ...
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0answers
175 views

What is the minimum and maximum cutoff frequencies for the antialiasing filter for this ADC?

https://www.analog.com/en/products/ad9675.html https://www.analog.com/media/en/technical-documentation/data-sheets/AD9675.pdf It says in the data sheet that the Anti-Aliasing Filter has : "...
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1answer
44 views

Do Audio Interface manufacturers use A-weighted Measurements to make specs look better?

Recently I came across a reputed music-tech teacher who said audio interface manufacturers use A-weighted measurements to show dynamic range in their specs so that they look better on spec sheets and ...
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2answers
266 views

Calculating filter coefficients of a Moving average with error correction

I have an oversampling ADC where I need to correct Gain/offset errors 'during' each conversion. This also links to my previous question - Moving average and linearization of two piecewise linear ...
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90 views

Moving average and linearization of two piecewise linear systems

I have 2 oversampling ADC's running parallelly, each to process data in a specific range of the input as shown below: Each ADC can process only half cycle range of a sine wave. Each ADC adds its own ...
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1answer
438 views

Sampling - Higher order harmonics

I have been studying about the sampling theorem and it seems that even though we sample at a frequency with the nyquist criterion, the harmonics (due to sampling process) remain within the nyquist ...
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1answer
417 views

How to plot noise shaped spectrum of First order Incremental Sigma Delta ADC's output?

A little background: This question is about viewing the output spectrum of incremental delta sigma modulators (IDSM). IDSM is a subcategory of general delta sigma modulators where the integrators are ...
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2answers
1k views

Higher order harmonics during sampling

I am studying about the sampling theorem in conjunction for ADC. I got little confused while reading about aliased frequencies. I see that as per the Nyquist theorem, the sampling frequency (fs) ...
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1answer
732 views

Are resolution increase and noise reduction from oversampling mutually exclusive?

Oversampling a signal means sampling it with a significantly higher sampling frequency than the Nyquist rate. As far as I know, there are three advantages: Easier design of anti alias filter Increase ...
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1answer
555 views

Calculating SFDR from FFT of ADC output

A few months ago, as part of my summer internship, I had performed interfacing of an ADC with FPGA (Zynq-7000). The goal was to take an analog signal from a signal generator, feed it to the ADC and ...
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1answer
571 views

Why use a 1-bit ADC in a Sigma Delta Modulator?

When looking at the discrete model of a Sigma-Delta Modulator as shown below, we can see that the quantizer is modelled as a white-noise source $e[n]$. From this model, we can derive the noise shaping ...
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1answer
371 views

Very fundamental question: by what number do you divide your ADC counts?

What number is it correct to divide by your ADC counts as a first step in converting counts to voltage? For example, in a 10 bit ADC, is it correct to divide by 1024 or 1023? I have always divided by ...
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71 views

Proper way to implement a decimation

I have an input signal with bandwidth 2.5 MHz. Let's say it's filtered using analog Butterworth low-pass filter. I would like to sample the signal using AD9203 10-bit 40 Msps ADC. If I understand ...
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1answer
889 views

How does harmonic distortion occur in ADCs?

We are currently testing an ADC at my workplace and the Total Harmonic Distortion is an important spec. It got me to thinking as to how it occurs in the first place 1) Can there be harmonic ...