expectations from a DFE ?

Started by mk in comp.dsp15 years ago 3 replies

Hi, I've been experimenting with adaptive filters for channel equalization and I have a problem with decision feedback case. Initially I...

Hi, I've been experimenting with adaptive filters for channel equalization and I have a problem with decision feedback case. Initially I started with a T/2 fractional linear equalizer adapted with LMS and then converted this to delayed LMS with two delays. I am currently not adding any noise just trying to compensate for the ISI generated by the channel although there is quantization error a...


non linear quantization

Started by mousecatz in comp.dsp14 years ago

Hi there! Can anyone help or give reference about this problem: what quantification scheme will be used and how will it be implemented when...

Hi there! Can anyone help or give reference about this problem: what quantification scheme will be used and how will it be implemented when i try to render an image in a cellphone screen considering a certain correction intensity of a square function f(x)=255*sqrt(x/255) and x ranging from 0 to 255 which represents image intensity? i really do appreciate any input. thanks much, mous...


Calculating derivatives of measurement results

Started by Sampo Niskanen in comp.dsp13 years ago

Hi, I have an application where I need to compute derivatives of measurement results in near-real time. However, noise and quantization...

Hi, I have an application where I need to compute derivatives of measurement results in near-real time. However, noise and quantization error of the measurements should affect the result as little as possible. What would be the best approach to this? I've tried searching on the net but haven't found much info. I guess it is basically a question of combining a [-1 1]/dt filter wi...


Re: Position and velocity from accelerometer

Started by Randy Yates in comp.dsp14 years ago 20 replies

Jerry Avins writes: > There must be more here than I can see. To measure velocity from > acceleration, integration is necessary. Even...

Jerry Avins writes: > There must be more here than I can see. To measure velocity from > acceleration, integration is necessary. Even digital integrators > drift. (How is left as an exercise for the reader. Answer on request.) How? I'm assuming that quantization isn't the issue here since by definition the input to a digital integrator is already digital. And I can se


Quantized least squares estimator and errors...

Started by kl31n in comp.dsp15 years ago 2 replies

I'll present my problem with an example. Let's assume I've an ADC sampling a signal and providing a mx1 column of samples that can be...

I'll present my problem with an example. Let's assume I've an ADC sampling a signal and providing a mx1 column of samples that can be represented as b + w being b the vector of the exact values of the signal and w the zero-mean error due to thermal noise and quantization error. The acquired signal can be modelled as A * x = b + w and I want to estimate the parameters in the vec...


Oversampling and quantization...

Started by kl31n in comp.dsp15 years ago 18 replies

Hopefully some of you can point me to the solution of this problem. If I oversample a signal, I quantize it and then I reduce the sampling...

Hopefully some of you can point me to the solution of this problem. If I oversample a signal, I quantize it and then I reduce the sampling rate with a decimator by a factor M, I can improve the QSNR by a factor of log2(M). Nice and easy. But what if I lower the sampling rate using a fitting technique? I mean if I know how the signal is done and I retrieve some parameters out of it using a f...


Levinson Durbin / Reflection coefficients

Started by Sebastian Gesemann in comp.dsp17 years ago 1 reply

Hi ! I want to learn more about different representations of the LP coefficients (ie reflection coefficients, spectral frequency line, and...

Hi ! I want to learn more about different representations of the LP coefficients (ie reflection coefficients, spectral frequency line, and so on). How to transform between those representations and what they actually mean. I'm searching for an easy representation which is robust against quantization and also allows the signal to be losslessly coded. (It should be easy to calculate the...


Newbie ? about FFT Bins and Resolution BW

Started by Paul in comp.dsp13 years ago 1 reply

If i understand this correctly, the inverse of the sample time will give us the frequency resolution, which is the same as the resolution...

If i understand this correctly, the inverse of the sample time will give us the frequency resolution, which is the same as the resolution bandwidth on a spectrum analyzer, right? So if I'm going into an ADC, and i want the receive KTB to stay 14dB or so above the thermal and quantization noise of the ADC, then i can sample at 100MHz, and the band width can be at the Nyquist, or 50MHz. So ...


Choice of digital signal processor

Started by Senfkuchen in comp.dsp10 years ago

Hi, I have a problem finding the right DSP for my purposes. The Situation is that I have a dspace System for analyzing and influencing the...

Hi, I have a problem finding the right DSP for my purposes. The Situation is that I have a dspace System for analyzing and influencing the Power Quality of the current Grid(harmonics). The System does its job but the results are improvable. Due to reasons of quantization Noise and Antialias I need a System with ADC that have 24 bits resolution and at least 100 khz sample rate. I need 4 channels...


[cross-post] dither generator on fpga

Started by alb in comp.dsp7 years ago 2 replies

Hi there, we are measuring from a quadrature encoder the raw sine and cosine and need to extract the angular position [1]. The position is...

Hi there, we are measuring from a quadrature encoder the raw sine and cosine and need to extract the angular position [1]. The position is then fedback to a PID which drives a motor. We've been told that dither may be efficient in removing spurious harmonics due to quantization errors which may affect the control loop only few days before pcb production, therefore the only possibilit...


mid-tread v mid-rise quantization?

Started by Richard Dobson in comp.dsp9 years ago 3 replies

Hello all, I am engaged in writing up various topics a propos sound and music computing in UK schools, in the context of the relatively new...

Hello all, I am engaged in writing up various topics a propos sound and music computing in UK schools, in the context of the relatively new Computer Science curriculum. Included in the curriculum (14-16 GCSE, and 16-18 A-Level) under the core topic of "data representation" is the sub-topic of audio sampling, including a basic understanding of the choice of sample resolution and the ac...


Re: Understanding bit widths requirements in Sigma Delta Modulators

Started by robert bristow-johnson in comp.dsp14 years ago

On May 22, 9:10 pm, Tim Wescott wrote: > somdeb wrote: > > I am trying to understand how bit-width requirements at different > > ...

On May 22, 9:10 pm, Tim Wescott wrote: > somdeb wrote: > > I am trying to understand how bit-width requirements at different > > integrators can be estimated... couldn't find much in literature. ... > > As a guess, I'd say it has to be big enough so that, at a minimum, the > quantization noise from your integrator is insignificant compared to the > noise you expect


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

Started by Don Pearce in comp.dsp14 years ago 290 replies

On Sun, 19 Aug 2007 23:26:16 -0700, dplatt@radagast.org (Dave Platt) wrote: > "Digital" and "subject to aliasing" are two different things. >...

On Sun, 19 Aug 2007 23:26:16 -0700, dplatt@radagast.org (Dave Platt) wrote: > "Digital" and "subject to aliasing" are two different things. > > As I believe the term "digital" is usually meant, it implies a > two-state (on/off) storage representation. It's not just that the > signal amplitude is quantized, but that the quantization uses a > power-of-two representation and storage system of so


Pseudo-random questions about a professional audio application

Started by Shaun in comp.dsp18 years ago 2 replies

Hello all, I've been toying with the idea of putting together a DSP box with some audio I/Os and am looking to get the highest quality audio...

Hello all, I've been toying with the idea of putting together a DSP box with some audio I/Os and am looking to get the highest quality audio fed into my DSP as possible. The engineering side of me wants to start by getting the skinny on 'the best' sampling techniques, ADCs, and pre-DSP stages to minimize (or ideally eliminate) quantization noise. However, the business side of me says I ...


Re: Theoretically Highest Quality of PCM Audio

Started by Bob Cain in comp.dsp18 years ago

BobGardner wrote: > > > > > If I am given a 16-bit fixed-point number of uniform quantization, I > > can surely say that the maximum...

BobGardner wrote: > > > > > If I am given a 16-bit fixed-point number of uniform quantization, I > > can surely say that the maximum theoritic dynamic range I can get is > > 96.329 dB > > Minor quibble... 96 dB is 6 dB per bit for 16 bits...the max signal is really > +-32767 or +-15 bits, right? so its 90dB.... Ah, but the largest signal swing is {32767,-32768} and the smallest is {


JavaScript JPEG Implementation Help

Started by mlazarov in comp.dsp15 years ago 1 reply

Hello, For a bit of fun I am currently writing an implementation of a monochrome baseline DCT JPEG encoder in JavaScript. I am currently using...

Hello, For a bit of fun I am currently writing an implementation of a monochrome baseline DCT JPEG encoder in JavaScript. I am currently using the IJG DCT implementation and the standard quantization and Huffman tables described in ITU-T.81. However the resultant images don't appear correct, I feel that this is because the information I've found relating to entropy coding is unclear and varies....


Delta Sigma modulation noise problem~! Help

Started by Leaf in comp.dsp16 years ago 5 replies

hi: We all know that DSM is good because it's abaility to push Q noise to higher frequency band. My question is does DSM only work for Q...

hi: We all know that DSM is good because it's abaility to push Q noise to higher frequency band. My question is does DSM only work for Q noise? What about if the data already corrupted by noise? therefore would DSM work if the noise is the combination of background and quantization noise.? I have done some matlab coding(first order) on it and it works a bit but i dont know if it's ...


Delta Sigma modulation noise problem~! Help

Started by Leaf in comp.dsp16 years ago

hi: We all know that DSM is good because it's abaility to push Q noise to higher frequency band. My question is does DSM only work for Q...

hi: We all know that DSM is good because it's abaility to push Q noise to higher frequency band. My question is does DSM only work for Q noise? What about if the data already corrupted by noise? therefore would DSM work if the noise is the combination of background and quantization noise.? I have done some matlab coding(first order) on it and it works a bit but i dont know if it's ...


Sigma delta conversion

Started by thom in comp.dsp15 years ago 1 reply

Hi everyone, I have a question about sigma delta conversion. I know that it permits to reduce quantization noise in a receiver. But what about...

Hi everyone, I have a question about sigma delta conversion. I know that it permits to reduce quantization noise in a receiver. But what about the noise at the input of the receiver? (I'm talking about the white noise floor that all RF signals contain) Thanks Thom


Increase resolution through decimation

Started by mariking in comp.dsp14 years ago 3 replies

Hi I need to take a standard 8bit ADC which samples at 40Msps increase the resolution by about 4 or 5 bits. I know that oversampling spreads...

Hi I need to take a standard 8bit ADC which samples at 40Msps increase the resolution by about 4 or 5 bits. I know that oversampling spreads the quantization noise over a wider bandwidth thereby decreasing the SQNR. So i can increase the resolution through decimation? How do I increase the resolution through decimation? It decimates the signal frequency but i don't physically know how to increa...