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Questions tagged [adc]

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9
votes
1answer
746 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 ...
6
votes
8answers
8k 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 ...
4
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2answers
1k 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 ...
3
votes
4answers
315 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 ...
3
votes
1answer
31k 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 ...
3
votes
1answer
486 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 ...
3
votes
1answer
487 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 ...
3
votes
2answers
218 views

Question about decimation/downsampling

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 ...
3
votes
0answers
37 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 ...
2
votes
2answers
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 ...
2
votes
1answer
143 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. ...
2
votes
0answers
157 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 ...
2
votes
0answers
59 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 ...
1
vote
3answers
696 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 ...
1
vote
1answer
317 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 ...
1
vote
1answer
402 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?
1
vote
2answers
534 views

Nyquist frequency and DC

Im studying the DSP book by Steven W. Smith. On page 41 he covers the Nyquist frequency. He makes up an example by writing the following. ... consider an analog signal composed of frequencies ...
1
vote
1answer
297 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 ...
1
vote
2answers
555 views

Calculation of actual analog input from bipolar ADC's output

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 ...
1
vote
1answer
293 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 ...
1
vote
1answer
178 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 ...
1
vote
1answer
296 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 ...
1
vote
1answer
732 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 ...
1
vote
1answer
299 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?
1
vote
1answer
51 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 ...
1
vote
0answers
25 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 : "...
1
vote
0answers
52 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 ...
1
vote
1answer
239 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 ...
1
vote
0answers
125 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 ...
1
vote
0answers
71 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 ...
1
vote
0answers
86 views

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 ...
1
vote
2answers
461 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 ...
1
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0answers
22 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 ...
1
vote
0answers
46 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/...
1
vote
0answers
205 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 ...
1
vote
0answers
165 views

Processing IQ signals [closed]

Signal Characteristics: The IF (I/Q) signal consists of a DC component and an AC component. DC Component: 2.52V; AC Component: 1.72 – 2.04 V (V P-P); BW: 20Hz - 500kHz; Power: 20dB Requirement: Now ...
0
votes
1answer
64 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 ...
0
votes
2answers
313 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) ...
0
votes
3answers
195 views

Does perceived ADC resolution, range and precision depend on fixed point format? What is the best way to deal with this for signal processing?

I am working on a system that is implementing a digital filter that was designed for another system that had an FPU and a 12bit ADC. The system that I am working on is using the same filter without an ...
0
votes
1answer
31 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 ...
0
votes
1answer
70 views

How can i record 1 MHz signal and do a real-time processing in a PC? [closed]

I have a 1 MHz signal from transducer that needs to be analyzed in real-time condition, so the sampling needs to be more than 2 MHz. It consists of digital filtering, turn into spectogram and feed ...
0
votes
1answer
645 views

Uniform quantizer for gaussian input signal

I have a gaussian signal $x$ with zero mean and unit variance. I am quantizing it by using a uniform quantizer of step size $q$ calculated by $$q = \frac{x_\mathrm{max} - x_\mathrm{min}}{2^{M_\mathrm{...
0
votes
1answer
352 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; ...
0
votes
1answer
73 views

Determining the features of the DSP

I need to sample a signal of 40MHz with a sampling frequency of 120MHz at least with a 8/12 bits ADC and send them through the USB serial port of a PC. That means the serial communication bandwith ...
0
votes
1answer
148 views

What is Audio codec in simplified term?

I am trying to understand what a codec actually is Wikipedia says In hardware, audio codec refers to a single device that encodes analog audio as digital signals and decodes digital back ...
0
votes
1answer
697 views

Calculate THD From DFT Plot

Consider the following DFT plot below, showing the output spectrum of an 9-bit ADC. I want to calculate the THD (Total Harmonic Distortion). I am wondering how to do it correctly. I am aware of the ...
0
votes
1answer
583 views

Quantization error in sampling

Consider the analog signal, $$x(t) = 2\cos(3000\pi t)+3\sin(4000\pi t)+7\cos(6000\pi t)$$ If the sampling rate is 8000 samples per second and quantized at 8 bits, find: Discrete values at any two ...
0
votes
1answer
9k 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: ...
0
votes
1answer
1k views

Order Analysis Signal Processing

I'm currently working on vibration detection machine used to detect unbalance from a rotating shaft, rotating from 300-2500 Hz. I have both the tacho signal ( 1 PPR ) and the vibration from transducer....
0
votes
1answer
123 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 ...