## Quantization of bands in frequency domain?

Started by in comp.dsp10 years ago 4 replies

Hi all - Apologies for what is probably a horribly naive question - but Google has been no help and I'm extraordinarily rusty with this stuff...

Hi all - Apologies for what is probably a horribly naive question - but Google has been no help and I'm extraordinarily rusty with this stuff at the moment. Say I have a signal sampled at a depth of 8bits, 10kHz, and I take an N-Point FFT. I understand there will be N/2 bands, each representing a width of 10000/N Hz, but what will be the quantization/depth of the levels represented by each b...

## vector quantization problem/question

Started by in comp.dsp16 years ago 5 replies

Hi I am working on a project about noise suppression. Part of the algorithm that I am designing is based on vector quantization. I am...

Hi I am working on a project about noise suppression. Part of the algorithm that I am designing is based on vector quantization. I am wondering which training algorithm I should use? Here is an example: If I have a 3D-vector (x,y,z) and each coordinate of this vector is random but limited to an interval from say 0 to C where C is a constant, the directional variance will not be mo...

## application of vector quantization on cepstral coefficients

Started by in comp.dsp13 years ago

please give me examples of cepstral coefficients in speech recognition .and how we can apply vector quantization on it.

please give me examples of cepstral coefficients in speech recognition .and how we can apply vector quantization on it.

## IIR quantization

Started by in comp.dsp18 years ago 3 replies

In the matlab filter design filter box, when I click the Quantization button after design a IIR, the freq response seems very different....

In the matlab filter design filter box, when I click the Quantization button after design a IIR, the freq response seems very different. I cannot find the place where you can configure how many bits for the system? Where do you specifiy that you are using a 16bit or 32bit system? thanks Andrew

## Quantization of fixed point filter coefficients.

Started by in comp.dsp16 years ago 1 reply

This post is a retake on the 'quantization of filter coefficients' issue. Let me present the issue in the following. I have designed a...

This post is a retake on the 'quantization of filter coefficients' issue. Let me present the issue in the following. I have designed a filter (notch, cut-off 55.7Hz) which is a bi-quad. The transfer function is : H(z) = 1 + (-1.992)*z^-1 + (0.994)*z^-2 -------------------------------- 1 - (-1.836)*z^-1 - (0.852)*z^-2 Now I am implementing this filter on a 16-bit fix...

## Phase of harmonics after Quantization of sinusoids

Started by in comp.dsp13 years ago 14 replies

If I look at a spectrum of a uniformly quantized sinusoid, there are harmonics at multiples of the input frequency. Does someone know how can I...

If I look at a spectrum of a uniformly quantized sinusoid, there are harmonics at multiples of the input frequency. Does someone know how can I predict the phase of those harmonics for the case of single as well as two tones inputs? As quantization is not a linear process, therefore the phase of the harmonics should not be just multiple of the fundamental's phase. The literature mostly talks abo...

## Quantization Error

Started by in comp.dsp6 years ago 12 replies

I wonder, How could the quantization (by truncation) error, E, for negative fractional numbers represented using ones complement is bounded...

I wonder, How could the quantization (by truncation) error, E, for negative fractional numbers represented using ones complement is bounded by 0

## LLR quantization in BICM ..

Started by in comp.dsp9 years ago 2 replies

Hi, When we compute the true loglikelihood ratios in bit interleaved co-ordinate modulation, it has a factor of the noise variance and hence the...

Hi, When we compute the true loglikelihood ratios in bit interleaved co-ordinate modulation, it has a factor of the noise variance and hence the LLRs can be very large when the SNR is high(or equivalently the noise variance is low). The LLRs need to be quantized to be sent to the decoder. Can anyone explain or proivde a reference to the criteria used for LLR quantization. Should th

## Question about quantization

Started by in comp.dsp17 years ago 5 replies

I've got transfer function H(z) and determined location of poles and zeros. How can I recalculate location of poles and zeros using a...

I've got transfer function H(z) and determined location of poles and zeros. How can I recalculate location of poles and zeros using a minimum quantization level of 0.125 for direct form II, cascade, and parallel structures? Where can I find sample solutions for similar problems? Any online tutorial? Is there any Matlab function which solves this problem? Thanks in advance.

## Translations to French

Started by in comp.dsp16 years ago 2 replies

I have to write a one-page French abstract of my thesis, and I'm having trouble finding the French translation of several terms. If someone...

I have to write a one-page French abstract of my thesis, and I'm having trouble finding the French translation of several terms. If someone out there could help me out with the following terms: Vector Quantization Codebook (in the context of vector quantization) Lossy data compression Computing power (as in the CPU power, in MIPS/FLOPS, required to run certain app...

## Dithering for

Started by in comp.dsp15 years ago 37 replies

Hopefully some of you guru's here can set me straight here. In an attempt to reduce quantization spurs, I have read about dithering. I have...

Hopefully some of you guru's here can set me straight here. In an attempt to reduce quantization spurs, I have read about dithering. I have seen wideband dithering and narrowband dithering. All of this is done in the analog domain prior to the sampling. My question is: Why can we not simply add a random LSB (+/- 1) to each of the samples AFTER sampling to reduce quantization spurs ? ...

## Vector Quantization for Speech Compression

Started by in comp.dsp17 years ago 4 replies

Hi, As my research project, I'm going to study a variation of VQ when applied to speech signals. As a starting point, I'm trying to...

Hi, As my research project, I'm going to study a variation of VQ when applied to speech signals. As a starting point, I'm trying to implement what I understand as the "standard" vector quantization, so that I can later implement the extensions I want to study, and compare the results. However, I'm having a hard time getting results of a minimally acceptable quality (I could post a...

## Coefficient quantisation for FIR filters

Started by in comp.dsp11 years ago 7 replies

Hi, can someone tell me (a hint perhaps) why there is a larger effect on the filter response after coefficient quantization in IIR filters than...

Hi, can someone tell me (a hint perhaps) why there is a larger effect on the filter response after coefficient quantization in IIR filters than FIR filters. Several books mention this but do not go on to explain it in detail. Is it because of the feedback term in IIR filters? or is the coefficient quantization sensitive to poles than zeros?

## reciprocals for quantization

Started by in comp.dsp15 years ago 1 reply

Hi, I'm building a quantization table to use with the IMG_quantize function on a TI DSP to quantize the DCT of an image. The function basically...

Hi, I'm building a quantization table to use with the IMG_quantize function on a TI DSP to quantize the DCT of an image. The function basically does this: short quantValue (short v) { int q, round; round = 1 < < (shift - 1) q = (v * recip + round) > > shift return (short) q; } I used the algorithm to find the reciprocal on Jones page: http://www.cs.uiowa.edu/~jon

## uniform scalar quantizer

Started by in comp.dsp13 years ago 13 replies

How does one design the optimum uniform scalar quantizer for a specific Gaussian input? All the literature I can find on quantization seems to...

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 just the design - selecting delta. I have seen it derived under entropy constraints, but I would ...

## IIR filter structures and coefficient quantization sensitivity

Started by in comp.dsp10 years ago 2 replies

Hi, I'm trying to implement a high order IIR filter on a fixed point ARM processor using a parallell second order section filter...

Hi, I'm trying to implement a high order IIR filter on a fixed point ARM processor using a parallell second order section filter structure. I'm using 16 bit coefficients and 32 bit filter states. I think I'm on the safe side when it comes to quantization noise, but so far I have been using a Direct Form 1 implementation of the 2nd order sections and the frequency response after coefficient q...

## ADC Interpolation Gain

Started by in comp.dsp11 years ago 11 replies

Hello, I've been reading a lot about increasing ADC quantization gain through oversampling and then applying an interpolation filter. I...

Hello, I've been reading a lot about increasing ADC quantization gain through oversampling and then applying an interpolation filter. I understand that for every 4x oversampling you can increase the SNR by 6 dB or 1-Bit and that lowers the quantization noise floor. However, say my ADC is sampling two tones at 1 kHz and 2 kHz using a 14-bit theoretical ADC. Theoretically my SNR is 6 dB * ...

## As good as it gets? :( Fixed point frequency response error from quant. noise

Started by in comp.dsp7 years ago 3 replies

Hi! I'm simulating a Direct Form 1 biquad using fixed point arithmetic in Matlab, and I'm having some problems with frequency response errors at...

Hi! I'm simulating a Direct Form 1 biquad using fixed point arithmetic in Matlab, and I'm having some problems with frequency response errors at low frequencies compared to floating point filtering. The errors are not due to coefficient quantization, but originates from the quantization after the accumulator in the feedback path of the biquad. I'm simulating a 24-bit architecture (I'm not t...

## Vector Quantization: Problem with designing codebook

Started by in comp.dsp16 years ago 12 replies

Hi I am trying to do vector quantization for noise-free speech segments. The algorithm I have programmed works like this: 1) Update...

Hi I am trying to do vector quantization for noise-free speech segments. The algorithm I have programmed works like this: 1) Update 240-point frame F with pre-emphasized block x of 10 speech samples. 2) Update estimate of power spectrum P based on updated frame 3) Calculate vector B=[b1 b2 b3 .....b17] where b1=sum of amplitudes in 1st bark scale b2=sum of amplitudes in 2nd bark ...

## mu-law companding

Started by in comp.dsp14 years ago 1 reply

hi all, I'm doing some tests with mu-law companding. I have a speech signal with Fs = 16 kHz, 16-bit. I test on 2 methods to encoding in...

hi all, I'm doing some tests with mu-law companding. I have a speech signal with Fs = 16 kHz, 16-bit. I test on 2 methods to encoding in 8/4/2 bit: - 1st methode: using uniform quantization 256/ 16/ 4 levels. - 2nd methode: using mu-law to compand sigal before, then using uniform quantization 256/ 16/ 4 levels, then using mu-law inrerse. In all three cases, the SNR with mu-law companding ...