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i have one doubt. when A and B system are cascade, then if the system is linear time invariant system even A and B are interchanged, no change in result. quantizer is a nonlinear system. but even the sampling and quantization is interchanged the entire result is unchanged and same result (...)
hii frends..... I still can't be able to make a difference between sampling and quantization..i mean i have read a lot on both of them....i mean books says that sampling's only time discrete and quantization's both(time-amplitude discrete)....but still m confused.... plzz (...)
There are a few problems with your code... The best way to define a sinewave is: A=1; n=7; N=2^n; % simulation length fs=1e2; % sampling frequency t=(0:N-1)/fs; % time (sampling points) f=3*fs/N; % sinewave frequency x=A*sin(2*pi*f*t); % cw sinewave r=10; % number of bits of resolution R=2^R; % number of quantization levels q=fl
I think you need some basic understanding of ADC. First sampling and quantization then switch to concrete ADC architecture
Hi, I hope you are not looking for DIRECT digital down conversion. I had used digital downconversion for a GPS receiver. It is fairly easy. you follow in digital all the process of analog. However you need to be careful about sampling and quantization levels. B R Madhukar
Hi all, I am wondering for a 12-bit resolution ADC, how big of a sampling capacitor at the front end should be in order to surpress the kT/C noise and opamp thermal noise from the later stages? Peoples used 6pf before, I think it is way too big. Any ideas?
To convert an analog signal into digital signal two steps are required 1. sampling 2. quantization We can perform these operations in any order to get a digital output.But why it is common to do sampling first? Looking forward for reply. Thanx in advance.
Dear all I need the following the paper, but i don't access to it, if you can ,pls send it for me. thanks you for your help. Chang,H., ?Presampling filtering,sampling and quantization effects on the digital matched filter performance? Proceeding of International telemetering conference,pp.889-915,San (...)
I need mathematical examples about the subjects in image processing: -filtering in the spatial domain. -filtering in the frequency domain. - Histogram equilization. -Image sampling and quantization. -Gray Level Transformations. Anyone can help me in that?
Hi all What is the relationship between "sampling frequency" and "quantization noise" in audio signals?
how to design a over-sampling filter to reduce quantium noise in the process of DA converting for audio playback???can you tell me the general theory about it??and what useful book i can refer to ????
Hi Process gain is defined as improvement in signal to quantization ratio when using oversampling. PG = 10 * log10(fs / (2 * BW)) BW = output BW after decimation. To calculate PG you need to know BW, so specify the output BW or decimation ratio then i can help you. Regards
quantization error in a duty-cycle modulated signal: When a pulse train as depicted below is sampled it will result in another pulse train which represents the error. Assuming the area under the error pulses is An, then the error should be in between ?Ts and +Ts where Ts is the sampling frequency. In the paper ?Analog-to-Digital (...)
AoA to ALL! I want to read a sound file in matlab, and set the sampling frequency to 8K. and represent each sample in 8-bits. play the result and also plot the frequency spectrum. i expect the spectrum should be from 0 to 4khz. plz tell me how to do all these in MATLAB. simple & early reply is required.
Hi, all I noticed for some SD ADC designs, ppl use CDS to decrease integrator leakage and flicker noise. For those of designs that circuit noises are the dominant noise sources (i.e. quantization noise is not so obvious), how can I model flicker noise and white noise properly if CDS is employed? thanks. -TiwstedNeurons
you should choose anathor sampling frequency. for example, fs=64MHz. as to your said,fin/fs=Mc/M. however, Mc must be integer.right? you should check it. I found your choose is wrong.:) if it's still wrong, you can upload the results image. let us discuss it.
oversampling reduces the quantization noise density.
An analog, low-pass filter prior to the input of the ADC eliminates or significantly reduces aliased noise. The corner frequency of the filter must be lower than fsampling/2. Increasing the order of the filter can minimize the noise.
In 2001, Abidi published a paper of "A 6-b 1.3-Gsample/s A/D Converter in 0.35-um CMOS". Only 6-bit resolution is required, however, Abidi and Michael Choi added 1pF as input sampling capacitor. The thermal noise due to KT/C is only about 2mV, which is much lower than LSB quantization noise. Why they put so much capacitance there (...)
I want to know the relation of spur and non-linearity in ADC and what is the difference between harmonic and spur? in ADC because of non-linearity, input driving and s\h circuit at output we see that harmonics of input signal appear at ADC spectrum. The ideal ADC has the quantization noise (...)
I want to know the relation of spur and non-linearity in ADC and what is the difference between harmonic and spur? in ADC because of non-linearity, input driving and s\h circuit at output we see that harmonics of input signal appear at ADC spectrum. The ideal ADC has the quantization noise (...)
After sampling the discrete signal has to be rounded to its nearer digital value. hence we go for quantization.
Hi! What type of resolution: * in amplitude, in phase, in frequency, etc.? Normally you should know at least: * the signal sampling factor (SSF) N = Fdigitalization /F signal * the number of the accurate bits n * the moment (angle) of the first sample * the total number of bits * the frequency band of the signal... BR
hi one query for 10bit Nyquist Rate ADC . i am giving 1k signal input and sampling frequency is 4MHz. then what snr i expect therotically. snr = 6.02N+1.76 ==> 61.96dB but i have seen the snr equation is SNR=6.02N+1.76+10log(OSR) here i am applying the input fin=1k and fsamp= 4M so the OSR = fsamp/2*fin = 4M/2K = 2000 hence total (...)
If you do not use "coherent sampling" you need to apply a window function to your signal before the fft, see below.nsignal=4096; fs=44100; f=1001*fs/nsignal; % coherent sampling i.e. integer number of cycles (1001) in nsignal samples %f=1000; %non-coherent sampling. Use hann window below t=/fs; y=1*sin(2*pi*f*t); w=ones(nsignal,
Hello, I am trying to implement a behavioral model of a delta modulator in Matlab, consisting of an ideal comparator and a summing unit in the feedback path. Unfortunately the spectrum is not flat as expected and I get peaks at odd harmonics of the signal frequency (cf. attachment). Does this behavior occur because the quantization noise (...)
Look into jitter analysis of ADC's, Phase modulation, and DDS systems. Each can be helpful. the uncertainty generates sidelobes for the same reason phase modulation does. The equivalent index is low, so you probably will only see one sidelobe. The effects become more pronounced for high-speed ADC's sampling signals above Fs/2 (bandpass (...)
Hi, i have some doubts regarding following questions: how increase in sampling rate reduces resolution? how dithering helps in sigma delta adc? what actually noise shaping is? any help would be greatly appreciated and thanks in advance.
Runge Kutta is for solving differential equations, which is a completely different problem than calculating the integral of a sampled waveform. Provided that the requirements of the sampling theorem are fulfilled (no spectral components of the signal higher than 1/2 of sampling frequency), the time-discrete signal processing operations can be exact
i have code matlab of this compression but i have a probleme in the party of lloyd max ? i need for ur help plz i put only the party of max lloyd quantification % Lloyd-max algorithm using signal values % Signal : Signal Vector % tol : Tolerance % Initial : sampling levels % dist : distortion % qua
Came across these on a website, no answers though.. Guess it would be benificial to everyone if we can answer these! 1. What are the factors you consider for the selection of ADC ? 3. How do you determine the number of bits of ADC is required for you ? 4. Which factor determines the number of iterations in SAR done to approximate the input
designing digital pid... well,are u familaiar with Digital Signal Processing? if no,u can learn it very fast specially i recommend u to read the well known book writen by Alan V.oppenheim:Discrete-Time Signal Processing designing a digital copy of an analog system like filters and controllers with feed back is described in this book chapter seve
In general some should look at the dynamic range of the signal to be quantized. For instance if some assume a sensor with signal of 1 mVrms and noise of 10 nVrms over the sensor signal bandwidth, the dynamic range is 10^5. For an ADC to accuratelly quntize such signal, the ADC quantization noise (Q/SqRt(12)) RTI should be at least three (...)
Hi, Noise in pass band is mainly due to 1) Amplification of thermal noise in the band of interest. Remember that most of the times thae gains will be around 100dB or more in RF systems. 2) Intermodulation products, Harmonics of clocks, etc contribute more noise. 3) quantization noise during sampling if any (...)
Hi, SDM increases the sampling rate and using a Delta modulator kind of structre reduces the quantization noise. However this comes with a price. You need to use more number of bits for representation. It is very expensive for communication receivers. I hope you have considered this. B R Madhukar
I need you advice in choosing a precise DSP filter. I need an DSP chip. IC. I like to use it this filter as notch Filter to block certain frequency range but not limited of being flexible as an application may want. Frequency range to block is 0.5Hz to 2Hz, or 0.5-1Hz. The signal passing this filter will be a sinusiod from 0.1Hz to 10H
Well, it really depends on what 'order' of SD adc you have. The SNR is related to the resolution of the convertor and the amount of quantization noise. Here's the way of calculating it: I was always told in university that whenever you double the samping frequency, its like adding another bit and a half to the resolution. But thats (...)
The quantization noise is spread across the frequency range from 0 to the sampling frequency. If you sample twice as much, the qunatization noise density is half. It is to your advantage to sample much higher than the Nyquist frequency. If you do not want to carry the high data rate further in the system, you can low pass filter using more bits
What is your DAC sample rate? I'm guessing it's slower than 24MHz. As brmadhukar suggests, you need a low pass filter after the DAC to reject sampling images (they look like stair steps on an oscilloscope). Design a filter that passes the frequencies you want, and strongly attenuates the sample rate and higher.
Hi, I am desiging a sigma-delta modulator in 0.35um technology having 5-bit coarse quantization. For the switch capacitor integrator, I have chosen 32 sampling capacitor (Cs) of value 0.3pF each. and the value of integrating capacitor (Ci) is 32*0.3=9.6pf. Please suggest me some good layout technique for capacitor of this much large (...)
Hi Kris, on the fly I can answer question 2. You have a 10 bit resolution that means 2 in the power of 9 ( binary: 2x1+2x2+2x4+....+2x512=1023 ==>1111111111 max value) or 1024 different combinations. That means that 1 bit represents the analog value of 5V /1024= 0.02441 V is your sensitivity. so if you now measure 0.2 the output will be 0.2/0.024
SNR is in the desired bandwidth. If you oversample, the quantization noise is spread over a wider frequency range and the noise in your desired signal bandwidth goes down. You have to LPF the DAC output because it makes signals at large multiples of the sampling frequency plus and minus (...)
i think your question is not so clear... basically, to convert an analog signal to digital: sampling then quatization.
I has these IEEE papers about NOISE FOLDING and could upload them: 1. An approach to tackle quantization noise folding in double-sampling /spl Sigma//spl Delta/ modulation A/D converters Rombouts, P.; Raman, J.; Weyten, L.; Circuits and Systems II: Analog and Digital Signal Processing, IEEE (...)
what is the resolution in ur design? if the resolution is small then how much is the quantization noise level? if big then how about the thermal noise in the sc? how about the dc gain of ur opamp? if everything ok, then you have to increase the # of points in fft and meantime you have to use coherent sampling,that is u have to make sure (...)
In audio signal compression, people would like the quantization to be white and independent of the signal. To this end, the characteristic function of the signal should be "bandlimited". Dither is like antialiasing filter in sampling theory to limit the "band" of the signal's characteristic function when (...)
Hi I can give some ideas about how to caculate needed SNR at the input to the ADC. Obviously this is heavily dependent on ADC dynamic range, SFDR, sampling rate and more .... I think that the best solution is to study a complete datasheet of an ADC. is a very great source. Also texas instruments provides valuable info.
I am designing a 10bit pipeline ADC. The schematic simulation shows that the odd harmonics are too large(especially,the third harmonic is 55dB). Can anybody give me some suggestion on how to find the reason? Thanks. sampling swith opamp (settling time) reference (settling time)
I think Fin and Fsample shoudl satisfy: fIN / fSAMPLE = NWINDOW / NRECORD, fIN: Periodic input signal fSAMPLE: sampling/clock frequency of the ADC under test NWINDOW: Integer number of cycles1 within the sampling window, prime number NRECORD: Number of data points in the sampling window or FFT
Thesis: A Superconducting Bandpass Delta-Sigma Modulator for Direct Analog-to-Digital Conversion of Microwave Radio by John Francis Bulzacchelli Massachusetts Institute of Technology,2003 This thesis examines the potential of superconducting technology for realizing RF analogto-digital converters (ADCs) with improved performance. A bandpass