DSP

Fast integer distance formula
I have an approximation for the Pythagorean distance formula (magnitude of vector [x,y]) using integer arithmetic that I would like to improve. Currently I am using this: if(x<0) x=-x; if(y<0) y=-y; if(x < y) { int t = x; x = y; y = t; // ensures that x >= y } z = (y < ((13107 * x)>>15)) ? ... 7 Oct 2006 09:19

RS decoding
I m in the process to implement the RS decoder. I implemented syndrome calculation, berlekamp massey algorithm, chien search and forney algorithms. However, in my code the number of error locations from the chien search is always less than the degree of the error location polynomial obtained using berlekamp m... 4 Oct 2006 04:42

Timing Recovery for Blind Demodulation
Hi! I'm working on a simulation of blind QAM demodulation in Matlab. So far i have implemented AGC, Carrier Phase tracking loop and a CMA equalizer - but i have not yet implemented symbol timing recovery. I have seen numerous references to Band-Edge Timiing Recovery (BETR), wich seem to do the trick quite well... 9 Oct 2006 17:11

Digital FM demodulation
hello, I'm designing a receiver for FM demodulation and I have a little problem with the filters of the downconverter. Here's my specifications : FM carrier 10,7 MHz, 20 kHz deviation. I send to the modulator a 19.2 kHz sinus signal. At the receiver, I first band-pass filter the carrier : center to 10,7 MHz... 5 Oct 2006 03:18

IIR Filter Realizations
In most books, block diagram realizations of IIR filters are shown - these include Direct form1 and Direct form II also, transposed realization and so on. I was wondering what the point is. Essentially these are all state-space type realizations but in implmenting a filter we just use the difference equation. I ca... 4 Oct 2006 16:51

Signal to noise ratio equation for discrete data
Hi, I have a simple question (I think) but have got stuck googling it for hours without finding a definitive answer. I have a set of samples for a noisy signal which are passed through a matched filter and I need to work out the SNR. I have found the equation SNR=10log(mean^2/std.dev^2) and various equation... 4 Oct 2006 17:54

DM642 PCI Master reads not starting
Hi DSPers. I want to do a master PCI read from host memory. My test code looks something like this... Uint32 dsp_addr = 0x81000000; Uint32 host_addr = 0x1ef60000; Uint32 count = 64; Uint32 ctlreg; .... VFDM642_init(); CSL_init(); .... ctlreg = count << 16; PCI_xfrConfigArgs(dsp_addr, host_addr... 29 Sep 2006 05:21

FIR witn inverse sinc behavior on passband
Hi, I'm trying to implement a FIR filter on FPGA which can compensate DAC's sinc(x) roll-off. Since I have no experience on it and I am a pure digital hardware guy, I have no idea how to start. :( I guess what I need to know is the number of taps required and coefficients, I heard people use Matlab to figure the... 27 Sep 2006 18:23

IEEE Explore
Hi All, I have been trying (and failing, mostly) to use IEEE Explore to search for articles etc. recently. Has anyone else had problems? I've contacted the IEEE (both member services and the ombudsman) because I think the way it currently doesn't work is a tradgedy. I would encourage any other IEEE member... 24 Oct 2006 23:16

Systolix FilterExpress
While cleaning up my PC I came across an old copy of Systolix FilterExpress V4.1. I also have a licence but that expired on May 1, 2002. When I set back the PC clock all runs well. Now, when looking for a new licence I found that Systolix does no longer exist and that there has been a V5. Does anyone know where I c... 26 Sep 2006 09:03