adaptive quantization and transmission errors

Started by dudelmann in comp.dsp11 years ago 1 reply

Hi I am working on a backward adaptive non-uniform quantizer for use in wireless transmissions. More precisely my quantizer currently consists...

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 noisy wireless channel. As of now the errors are bringing the adaptive expander on the decoder side ...


Maximizing dynamic range of fixed point IIR filter

Started by Vladimir Vassilevsky in comp.dsp11 years ago 22 replies

Let's say we need to implement H(z) = P(z)/Q(z) in the fixed point. The typical implementation would be a cascade of biquads. So we factor...

Let's say we need to implement H(z) = P(z)/Q(z) in the fixed point. The typical implementation would be a cascade of biquads. So we factor P(z) and Q(z) and distribute poles and zeroes between the stages. The dynamic range of a filter is limited by overflow at the top, and by quantization artifacts at the bottom. We can try all variants of assignment of poles and zeroes to different s...


Encoding residual (LPC on speech signal)

Started by Carlos Moreno in comp.dsp15 years ago 10 replies

Hi, As part of my research project, I'm working on vector-quantization applied to an LPC-like encoding scheme. For each frame of speech...

Hi, As part of my research project, I'm working on vector-quantization applied to an LPC-like encoding scheme. For each frame of speech (I tentatively put a frame length of 128 samples -- at 8kHz sampling rate), I compute the optimal prediction filter (using the autocorrelation method), and then apply that filter to the signal (well, I apply 1-P to the signal, where P(z) is the optima...


Chamberlin state variable filter transfer function

Started by kimt...@gmail.com in comp.dsp12 years ago 2 replies

Hi, I am comparing coefficient quantization errors for second order IIR filter structures (for fixed point implementation). I have found...

Hi, I am comparing coefficient quantization errors for second order IIR filter structures (for fixed point implementation). I have found the Chamberlin state variable structure to perform well at low frequencies and have seen in the article "The modified Chamberlin and Zölzer filter structures" that the quantized pole distribution is dense in the low frequency area of the unit circle in th


jpeg compliance testing

Started by Nave in comp.dsp11 years ago 3 replies

Hi guys, I am working on a jpeg encoder decoder project. I have problems with testing compliance. I read the T.83 ITU document for...

Hi guys, I am working on a jpeg encoder decoder project. I have problems with testing compliance. I read the T.83 ITU document for compliance testing. It says if I have to test compliance of my decoder I have to have a double precision reference FDCT so that I will do FDCT(ref FDCT) on my decoded data. After quantization if I get back the input to the decoder my decoder is...


JPEG encoding

Started by destiny_nz in comp.dsp13 years ago

Hi guys, For the JPEG encoding processes, after the DCT and quantization of each 8*8 blocks, two Zig-Zag encoding modes can be used. One is...

Hi guys, For the JPEG encoding processes, after the DCT and quantization of each 8*8 blocks, two Zig-Zag encoding modes can be used. One is sequential encoding and another one is progressive encoding. While sequential encoding encodes coefficients of a single block at a time (in a zig-zag manner), progressive encoding encodes similar-positioned coefficients of all blocks in one go, followed by ...


how the delta sigma output is converter to binary form

Started by cmos_189 in comp.dsp15 years ago 1 reply

hello the output of the delta sigma modulator is a series of pulses of 1 and -1 so how does the final output is in the binary(bcd form)...

hello the output of the delta sigma modulator is a series of pulses of 1 and -1 so how does the final output is in the binary(bcd form) form. what is the role of the integrator in the delta sigma modulator how does the integrator remove quantization noise This message was sent using the Comp.DSP web interface on www.DSPRelated.com


how to understand sigma-delta adc in time domain?

Started by lxx.helen in comp.dsp12 years ago 6 replies

I'm trying to think of a way to understand sigma-delta ADCs in time domain. Up to my understanding, two key technology of sigma-delta ADCs...

I'm trying to think of a way to understand sigma-delta ADCs in time domain. Up to my understanding, two key technology of sigma-delta ADCs are oversampling and noise shaping. In frequency domain, oversampling evenly spreads the square(delta)/12 quantization noise between 0 and samping frequency fs. Then with the help of decimation filter, we can remove the noise out of baseband fB. So, the rem...