# 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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852 views

### Quantization Noise for Coherent Sampling - Phase Noise?

Update: See added thoughts at bottom of this post. Under general sampling conditions not constrained by what is described below (signal uncorrelated to sampling clock), quantization noise is often ...
9k views

### Nyquist Frequency Phase Shift

The figure below shows in dashed lines sinusoidal signals of the same frequency at three different phase shifts. The signals are then sampled such that the sinusoidal frequency is exactly a half of ...
33k views

### What is “Maximum Quantization Error”?

I have an formula for this "Maximum Quantization Error" but i dont know what it is based in. Its just thrown in my study material without further explanation. It is defined as: Q = \dfrac {\Delta ...
2k views

### How increasing the Signal to Quantization noise increases the resolution of ADC

Inside ADC we have a quantizer, when the sampled signal is passed through it, the signal values get discretized. The number of discrete levels in which the signal is discretized is called the ...
157 views

### Does delta-sigma ADC also reduce Gaussian noise on input signal to ADC or just quantization noise?

The motive for posing this questions arises from a difference of analysis between a colleague an myself. Our general environment is in the construction of an analog front-end which takes in signals ...
353 views

### Is it theoretically possible to perfectly quantize a continuous signal?

So, I'm completely new to digital signal processing, but while reading a piece this morning about quantization it got me daydreaming: could a machine ever be fast enough to sample the position and ...
72 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 ...
4k views

### Bandwidth with complex sampling

On the transmit side, I have a 20 MHz carrier frequency carrying a signal with bandwidth of 40 MHz (so 0 Hz to 40 MHz, center at 20 MHz). On the receive side, I have a dual channel ADC with each ...
503 views

### Real-time block processing setup on ARM

Newbie question here. I'm working on a system that is running a 32khz sampling rate, audio, 16 bit DAC. Previously, our system had a very hard latency requirement of 1 sample. So no problem, we ...
496 views

### Ultrasound Signal Processing Methods

I am sending 6.6Vpp square wave across a narrow-band, 40 kHz Transmitter to a narrow-band, 40 kHz Receiver. I want to find a very accurate distance between the two (sub millimeter). My assumption so ...
257 views

I am using an on-chip SAR adc where for some reason I can only get accurate signal reconstruction and filtering when I sample at almost 100 times my desired sampling frequency. Specifically, the ...
53 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 ...
377 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 ...
38 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 ...
194 views

### Any better way to detect Signal with ADC Overflow problem?

I am trying to create an algorithm to detect signal with "ADC overflow" as shown in picture on lower right. It happened because someone had incorrectly down converted an int16 signal into int8 signal. ...
253 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 ...
321 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 ...
60 views

### Modelling of quantization noise with logarithmic steps

I have to modell the quantization noise of ADC. I only know that the maximum relative error is 1 dB. Since this is logarithmic, I find it hard to formulate an appropriate model for the quantization ...
509 views

### Modeling ADC in Active Noise Cancellation

I'm tinkering in Matlab with a problem that's very similar to active noise cancellation. In the literature, the secondary path is described as the transfer function from the output of the adaptive ...
130 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
858 views

### Precision measurement of sine wave amplitude with ADC

I want to measure amplitude of a sine wave input precisely with a limited resolution ADC. As an example suppose that I have $1\textrm{ MHz}$ pure sine wave input to the $320\textrm{ Msps}$ $10$-bit ...
451 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 ...
117 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 ...
692 views

### comparison between Fourier transform and autocorrelation function

If the Fourier Transform of a signal is enough to determine its spectral density, why do we complicate our lives by defining the autocorrelation function?
442 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 ...
743 views

I have a $14$-$\textrm{bit}$ ADC which can take $-10\textrm{ V}$ to $10\textrm{ V}$ as input. So, $0$ to $16383$ (digital) represents the voltage from $-10$ to $10$. If I want to get the actual ...
47 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 ...
58 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 ...
26 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 ...
513 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 ...
662 views

### How can I mimic this ADC for a given resolution, sampling rate and input with MATLAB or Python?

I'm quite new to the area so I need help to progress at some point. Basically I have a signed 16 bit ADC which means it maps -10V to +10V range to 16 bit. So the max voltage +10V is 2^15-1 = 32767; ...
218 views

### Lock-In Amplifier Sampling Rate

For a digital lock-in amplifier (synchronous demodulator) I have a sinusoidal reference signal in the range of 10-15kHz, the amplitude and phase I want to observe changes very slowly <10Hz. My ...
317 views

### Frequency measurement from acoustic emission sensor data(VDC RMS)

Currently, I am facing a problem about understanding FFT concept and getting exact frequency with acoustic emission sensor data(VDC RMS data). I want to measure the sound frequency from the acoustic ...
11k views

### Analog to digital conversion using Python

I'm a beginner. I try emulate analog signal conversion to digital (including sampling by time and quantizing by level) using Python. Here is my code: ...
1k views

### How do you simultaneously undersample and oversample?

"Undersampling" and "Oversampling" are common terms when referring to the choice of sampling frequency for analog to digital data conversion. Is it possible to Undersample and Oversample a waveform ...
345 views

### Effect of rounding off ADC value

I have a 10-bit ADC with 8.5 bit ENOB. I have 2.5 quantization levels of thermal noise in front of the ADC. Is there a reason to process more than 8 bits from this ADC?
28 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 ...
74 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?
64 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 : "...
77 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 ...
465 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 ...
195 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 ...
179 views

### ADC sampling rate in OFDM baseband processor

I have optical OFDM baseband TX and RX implemented in FPGA. The design is tested using one FPGA board in loopback connection from DAC to ADC via coaxial cable. It works fine, the BER is about 1.10^-8 ...
79 views

### Usage of a TI DSP EVM and ADC card

I'm not quite sure if I can ask about a vendor-specific hardware here, please teach me if not. We have a TI's DSP EVM, one of EVMK2Ls (XEVMK2LX/XTCIEVMK2LX) and wanna do some digital signal ...
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### STM32 Discovery dev platforms [closed]

I'm still researching this but though I'd post asking about experiences. Looks like st.com offers a variety of STM32 Discovery dev boards for ARM CPUs to, among other things, play with DSP. But ...
23 views

### 'ADC' sort of conversion method to retain information

I have a program that reads 16 bit two's complement format data to plot/analyze graphs. I have a database text file with various decimals which represent real analogue data, ie. let's say they are ...
56 views

### Sigma Delta Sampling

I am using a Sigma Delta ADC and really understood the working of it I need to sample a signal at 8.5 Mhz. The SD ADC has a Demodulator and decimating FIR filter The Oversampling ratio options are 32/...
222 views

### How to choose sampling rate?

I am working on a FMCW radar and I want to sample the I/Q signals from the 2 receiving antenna (total 4 channels) simultaneoulsy and send the digital data to computer to extract range and velocity ...