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ADC quantizer question.

Hello, I am looking for some facts or specifications about an ADC quantizer. Firstly I want to know if it possible for quantizers to dynamically change their resolution? or is it fixed for a quantizer. If the quantizer can actually change its resolution, I would be very grateful if somebody c...

adaptive quantization and transmission errors

Hi I am working on a backward adaptive non-uniform quantizer for use in wireless transmissions. More precisely my quantizer currently consists of an adaptive compader (currently atan-based) and a simple uniform quantizer. This works very well. Trouble is: I am going to transmit data over a ...

Adaptive Equilization

I'm looking at the block diagram on page 247 of "Adaptive Signal Processing" from B.Widrow and S.D.Stearns. Anyway, the block diagram shows an LMS filter in the center, and the Quantizer on the bottom right. The output of the Quantizer goes to a subtraction element (which subtrats the LMS out...

How determine the path of signal?

I am digitizing the sampled signal be using a uniform quantizer, so the step (q) between two consective quantization levels is fixed and is "q = Vin/2^N" where 'q' is the quantization step, 'Vin' is the total range of quantizer and 'N' are the effective number of bits of quantizer. Now I want to ...

uniform scalar quantizer

How does one design the optimum uniform scalar quantizer for a specific Gaussian input? All the literature I can find on quantization seems to deal with analyzing specific quantizers, quantization noise probability densities and power spectra etc., but I cannot seem to find any specifics on j...

snr of quantizer using fixed logic

Hello all, I am doing SNR measurement of 8 bit quantizer implemented using "fix" logic (flooring towards zero for both + and - numbers). i am doing time domain and frequency domain estimation. TSNR = 43.6 dB (correct value). FSNR = 48.0 dB (in-...

Re: Dtihering, gain and again...

In article v5bBb.6707$Ho3.476@newsread1.news.atl.earthlink.net, Randy Yates at yates@ieee.org wrote on 12/08/2003 22:13: > robert bristow-johnson wrote: > > second moment, and we believe psychoacoustically that no one can hear > > couplings of higher moments. > > A belief which I've so...

Noise Shaping and Clipping

Consider a requantization system with noise shaping and dithering. The question is what to do when the sum of the signal, the noise feedback and dither exceeds the range of the output quantizer. A differentiator of the Nth order used as a noise shaping filter has the max. feedback of ~2^N. S...

Re: New Digital Audio Standard?

In article bsnpmq$du0ut$1@ID-167115.news.uni-berlin.de, Glenn Zelniker at glennz@z-sys.com wrote on 12/28/2003 18:41: > robert bristow-johnson wrote: > > > i don't know of any commercial product that actually does DSP in the 1-bit > > domain (except for the first stage of the decimator i...

Re: newbie question on deadzone quantization

Hi, > Can some one help me with deadzone quantization. What is its > difference when compared to normal quantization methods? There's no "normal" quantization, so to say. A quantizer is a mapping from a continuous set A of "signals" to a discrete set "D" of symbols such that every a in A...

Re: Fractional Saving

in article yLudnYt8VMfgj77ZnZ2dnUVZ_sOdnZ2d@giganews.com, snigdha at i_am_snigdha@yahoo.com wrote on 03/23/2006 16:26: > I have seen some posts regarding the implementation of IIR filters on a > fixed-point platform. I understand that using a cascade of DF1 IIR filters > combined with fract...

Re: how to understand noise shaping of sigma_delta in time domain?

On Nov 12, 11:27=A0am, "lxx.helen" wrote: > let's think of the noise shaping function for sigma-delta modulators. In > frequency domain, we say quantization noise is pushed to higher frequency > and then removed by lowpass filter. > > what I wanna do is to find a time domain understandi...

Re: projects in DSP

> > > > > "Rohit" == Rohit Pydimukkala writes: Rohit> I just started out with DSP and I am quite excited with my learning. Rohit> Now that I am interested in doing some small projects in DSP. Can Rohit> anyone let me know where I can find DSP projects on internet or Rohi...

Re: Dthering....

eric.jacobsen@delete.ieee.org (Eric Jacobsen) wrote in message news: ... > On Sun, 12 Oct 2003 01:12:58 -0400, Jerry Avins wrote: > > > Eric Jacobsen wrote: > > > > Jerry, you've stumped me. What's "fraction saving"? the way i would describe it is: 1st-order noise shaping with ...

Sigma Delta - Modeling s-function

Hey guys, I have a continuous-time sigma-delta converter that includes a continuous-time transfer function H(s) at the input, followed by a sampler, quantizer and a digital-to-analog converter (DAC) in the feedback path. I'm trying to model the transfer function H(s) that includes some non-i...

Re: IIR filter design

Erik de Castro Lopo wrote: > Bernhard Holzmayer wrote: > > ... > > Matlab caused a lot of pain when I tried to design even lower > > order filters (4th order Butterworth), when the relation between > > cutoff-frequency and sampling frequency decreases: > > try this: 4th order HPF and L...

Delta-Sigma Modulator Loop Filter analytical equation not useful?

Dear friends, I am encountering a confusion in Delta-Sigma Modulator. Most of the references use a linearized model to model the DSM, and an analytical transfer function can be derived. Refer to Shenoi's "Digital Signal Processing in Telecommunications", page 492, the denomenator of the trans...

The optimal quantization

Hi, Anybody knows who and where works in optimal quantization area? Max Lloyd quantizer was created 50 years ago. What is going on this scientific direction now? ...

Re: Linear PCM audio: 44.1 KHz, monaural, 1-bit-per-second

Andrew Reilly writes: > On Mon, 23 Jul 2007 10:35:03 -0400, Randy Yates wrote: > > > It's not the sample rate that prevents DSD from being linear PCM, but the > > fact that it does not utilize simple linear quantization. > > Yes, there's some fancy filtering up-stream, to ensure tha...

LLR quantizer

Hi, Can someone explain how to quantize LLRs values (which are real numbers) to finite precision i.e. discrete soft bit. I know that Es/No has impact on quantizer boundaries but I just dont understand how to map correctly LLRs to discrete soft bit to maximize the decoder performance. This is beca...

Re: Compensating DAC for low bit-resolution with high sample rate

The added accuracy by oversampling can be explained easily: The DAC produces the same absolute amount of quantization noise, but it spreads over a wider bandwidth. At least that's what I can show with an ideal quantizer in Matlab, and it's a good rule to remember. With real-world converters ...

Re: sigma-delta

kbc32@yahoo.com (kbc) writes: > Hi, > > Consider a sigma delta adc which first oversamples, does > noise-shaping and then filters and decimates to give final output > at Nyquist rate and with 16 bits per sample. OK, so this is a standard delta sigma ADC. Fine. > For this fin...

Re: Quantized FIR Coefficients and MSE Optimization

"Jim Beasley" wrote in message news:fad45c70.0306261456.30b58633@posting.google.com... > I have an MSE algorithm that optimizes using a closed-form solution > (based on estimates of the statistics). > > However my filter coefficients are quantized. I am sure I can get > further impro...

Sigms Delta Modulator Question

Hi all, If input a step respond into a SDM with a 1 bit quantizer, the output would be a stream of '1' and '0' s. IS that stream PCM or PDM?? Can I tell the dynamic range form the bit stream?? For example a 50nA step input with a output bit strem of "101010111011" and repeat. what ca...

Re: Bifurcations in delta-sigma A-to-D converter

For a first order loop, holding the voltage constant at 1/2 scale (also at 1/8, 1/4, ...) will show some limit cycle. This is a well documented problem. A higher order loop or a quantizer of more than 1 bit will reduced this problem. Another technique is to add random noise in the loop, jus...

Delta-Sigma Modulator question

Dear all, In a Delta-Sigma Modulator, after the quantizer, the output bit stream (+1 and -1) is fed back to the input and being subtract from the input(assuming first order loop). However, none of the references that I read mentioned how large this feedback signal should be. For example, if t...

Re: Digital Delta-Sigma DAC

In sci.electronics.basics Davy wrote: : Hi all, : I want to design a digital delta-sigma DAC. It includes a pulse density : modulated module and RC low-pass filter. : The pulse density modulated module is a Delta-Sigma type (one adder and : one substractor). But why use Delta-Sigma type ...

Re: Random variable through filter - D/A conversion

Thank you very much Michael. This is digital-to-analog with uniform quantization I am assuming. Basically a quantizer and a sample-and-hold filter in cascade. So the filter will be a rect function. My input will be Gaussian but I am trying to find a general method to find the output PDF of th...

Re: Phase of harmonics after Quantization of sinusoids

Rune Allnor wrote: > On 23 Aug, 21:32, "SammySmith" wrote: > > > I assume that the number of samples per cycle donot change throughout the > > quantization process...at the moment I am just assuming ideal conditions. > > So the output after quantization is like a ZOH output. Can phase ...

Re: STUPIDENT::Re: SNR of quantisation noise

> > it does. .. well, if (as mentioned earlier) the assumption holds that quantization noise is AWGN. In the voltmeter example, it probably is not: I need to be some "dithering" signal that prevents the measured value from getting "stuck" on for example 0.05 V, but instead causes it to jump ran...

Reference on quantization noise modeling

Does anyone know some examples where quantization is modeled by a linear model as follows: y = Q(x), modeled as y = a*x + q, where q is an additive noise, preferably white Gaussian. See the following paper for an example: Fletcher, A.; Rangan, S.; Goyal, V. & Ramchandran, K. Robust Pre...

how can I decide the points of blackman window?

Hi:all I am trying to measure the SNR of a second order sigma-delta ADC. I want to just do a FFT analysis for the output of the quantizer. So, I collect 65536 points for FFT. I was told that I should use a Blackman window here.But how many points of the blackman window should I use? Here are som...

Re: Questions about equivalents of audio/video and digital/analog.

Don Pearce wrote: > ... If you are doing digital signal processing, you are > doing arithmetic on the numbers that come out of an AtoD converter. > You can't do that with some voltage levels out of a quantizer. Transversal and recursive filters and correlators have been built that oper...

Re: Maximizing dynamic range of fixed point IIR filter

On Dec 22, 11:50=A0pm, Vladimir Vassilevsky wrote: > Tim Wescott wrote: > > On Tue, 22 Dec 2009 20:32:58 -0800, robert bristow-johnson wrote: > > > > it's not a proof, but a sorta rule of thumb that i thought made sense i= s > > > to start with the pole pair (i'm gonna assume everythi...

Re: Question about computing a "moving variance"

in article 35SdnWAbpqYEBqDfRVn-qA@rcn.net, Jerry Avins at jya@ieee.org wrote on 03/20/2005 10:49: > Rick Lyons wrote: > > ... > > > x(n)---> (*)------> (+)-----------+----> y(n) > > ^ ^ | > > | | v > > [1-p] |...

Re: 1-bit ADC for RF, is it possible?

> For RF transmission, I think sigma-delta techniques are a very big deal... From what I understand all S-D converters use a feedback loop. Basically this loop is used to trade sampling frequency with dynamic range. Without this feedback loop the system is a simple sampler with a 1-bit quanti...

Re: fixed point precision in matlab

On Jun 24, 3:44 am, raj wrote: > Hai, > > I want to view the the numbers with more precision > for example: > > inp=[0.01 0.02 0.03]; > outfile1 = fopen('imp_in.txt','w'); > fprintf(outfile1, '%15.15f\n', Inp); > > with the above i am getting the imp_in.txt file contents as >...

Re: Shameless Plug

Tim Wescott wrote: > Embedded Systems Programming Magazine has sunk to a new low -- they made > _my_ article their cover story in the July issue. > > Tee hee. > > http://www.embedded.com/showArticle.jhtml?articleID=22101730 > Nicely done- I was anxious to see a analytical ex...

Re: IIR Form to prevent Limit Cycles?

jeff, approach 1. a second order IIR section that is free of zero input limit cycles is given on page 726 of sanjit k mitra book. fig 12.54. 3rd edition, digital signal processing. I am not too confident about this structure as limit cycle oscillations are caused by the quan...

Re: sigma delta modulator design.

"venkatax" writes: > > Sorry if that seems harsh, flippant, or otherwise offensive, but there's > > just so much free advice/time I'm willing to give, and once your > > questions start requiring more time than that, we arrive at this > > point. Perhaps others here will be willing to answer ...