## puncturing clock in viterbi

Started by in comp.dsp18 years ago 1 reply

Respected sir, with ur valuable information i have implemented a viterbi decoder with k=7,1/2 decoder with ...

Respected sir, with ur valuable information i have implemented a viterbi decoder with k=7,1/2 decoder with puncturing capability satidfactorily.... . i have also implemented a puncturing unit which punctures the 1/2 code to rate 2/3 and 3/4 rate... using fifo ram and state machine.. and it is working... but i have a problem with the output data r...

## Soft Decision for Viterbi Decoding..

Started by in comp.dsp14 years ago

Hello all, This is my first post here. :) I am currently working on a 802.16d receiver where I have to combine signals from 4 antennas and...

Hello all, This is my first post here. :) I am currently working on a 802.16d receiver where I have to combine signals from 4 antennas and then pass on soft decisions values to the Viterbi decoder for the final output. I have managed to figure out how to combine the 4 signals and figure out which point was transmitted. I used a method described by a user on this very forum named James Sungj...

## TCM metric computation

Started by in comp.dsp17 years ago 2 replies

Hi, I am writing a Matlab simulation of "Pragmatic-TCM" (see "A pragmatic approach to trellis coded modulation", Viterbi et al, IEEE...

Hi, I am writing a Matlab simulation of "Pragmatic-TCM" (see "A pragmatic approach to trellis coded modulation", Viterbi et al, IEEE Comms magazine, July, 1989, p.11). One point I am unsure of is how to compute the metrics for the Viterbi algorithm which decodes the least-significant bits of the received signal point. I understand that when you receive a point for decoding, you first ...

## One dimensional modulation - advantage!!

Started by in comp.dsp19 years ago 1 reply

Hi All, I have collected few classic papers on channel coding,MLSE and Viterbi Algorithm written by the pioneers during 1966-1972 - Including...

Hi All, I have collected few classic papers on channel coding,MLSE and Viterbi Algorithm written by the pioneers during 1966-1972 - Including works of Hancock,Gallager,Viterbi,G.D.Froney,Omura,Lucky etc. I have found a later paper written by Ungerboeck at IEEE trans on info theory,Jan,1982 where he introduced the idea of set partitioning later popularized by S U H Quereshi et al as RSSE - ...

## 16-PAM Demodulation and Viterbi

Started by in comp.dsp17 years ago 1 reply

Hi, If I have a 16-QAM demodulator I know I can use the I and Q values to access a lookup table and output soft codes for a Viterbi uisng...

Hi, If I have a 16-QAM demodulator I know I can use the I and Q values to access a lookup table and output soft codes for a Viterbi uisng LLR What do I do if I'm using 16-PAM? If my information is right its just amplitude modulation. So out of the demodulator I will get 1 of 16 values. How do I then create the soft codes indicating how strong, or weak the '1's and '0's are? Thanks Mike ...

## Viterbi Decoder (Does the complexity depend on the Code Rate)

Started by in comp.dsp10 years ago 3 replies

Hi, Does the complexity of the viterbi decoder of a 1/N-rate convolutional code increase with N? The constraint length L is kept...

Hi, Does the complexity of the viterbi decoder of a 1/N-rate convolutional code increase with N? The constraint length L is kept constant? My point of view: to decode 1 information bit, one has to process N channel bits. Hence, when N increases, the number of necessary operations increases too. Is that true? Thanks!

## speaker verification with HMM

Started by in comp.dsp15 years ago

Hi. I am trying to write a program to verify the speaker. I'm confusing with the viterbi algorithm in Hidden Markov Model(HMM). As I know,...

Hi. I am trying to write a program to verify the speaker. I'm confusing with the viterbi algorithm in Hidden Markov Model(HMM). As I know, the viterbi algorithm is used to find the best path of the sequence. I would like to know how this algorithm can help when I want to verify whether the speaker is imposter or not. [the log likelihood computed is too small. It is around -300 for the...

## cdma2000 viterbi decoder using TMSC67 DSP (fixed point)

Started by in comp.dsp13 years ago

Hi Does anyone know where I can find the code for implementing the subject decoder? Ideally, I am looking for a TI application note or some...

Hi Does anyone know where I can find the code for implementing the subject decoder? Ideally, I am looking for a TI application note or some similar document. I searched the TI website but couldn't find a lot there. Note that my DSP would not have a viterbi coprocessor(VCP) so the implementations utilising VCP will not be useful for me. Thanks

## Rate 2/3 convolutional encoder + viterbi decoder

Started by in comp.dsp11 years ago

Hi, thanx for answers to previous mails. I did simulation of viterbi (hard decision) of rate 1/2 ..soft decision still stuck on that...

Hi, thanx for answers to previous mails. I did simulation of viterbi (hard decision) of rate 1/2 ..soft decision still stuck on that LLR- Soft decision understanding part :-(. now my current question is, lets say i use 2 rate 1/2 decoders and do puncture pattern as {1,1,0,1} assuming this is the trellis poly2trellis( 4, [17 15]) (matlab notation..its in octal format) in decimal it is ...

## best state traceback in Viterbi

Started by in comp.dsp17 years ago 3 replies

Hi All, I am using traceback approach for viterbi decoding. After acquisition of a block of D data,I choose the minimum state as best...

Hi All, I am using traceback approach for viterbi decoding. After acquisition of a block of D data,I choose the minimum state as best state to start traceback. I am implementing normalisation on path metrics to constrain the bit width. Now my question is while finding the minimum state as best state,is there any chance of occuring more than two or three states having minimum value.If...

## Viterbi algoritms for STTC

Started by in comp.dsp13 years ago

Hi all, Can anybody please tell me if there is any different between the viterbi algorithm for Convoluntional code and that for Space time...

Hi all, Can anybody please tell me if there is any different between the viterbi algorithm for Convoluntional code and that for Space time trellis codes. I have tried using the decoding approach for convoluntional and trellis coded modulation (TCM) to decode my 2 states BPSK space time trellis code but the ber that is producing is quite embarasing. Can anybody please help me out. I am writin...

## Viterbi algoritms for STTC

Started by in comp.dsp13 years ago 4 replies

Hi all, Can anybody please tell me if there is any different between the viterbi algorithm for Convoluntional code and that for Space time...

Hi all, Can anybody please tell me if there is any different between the viterbi algorithm for Convoluntional code and that for Space time trellis codes. I have tried using the decoding approach for convoluntional and trellis coded modulation (TCM) to decode my 2 states BPSK space time trellis code but the ber that is producing is quite embarasing. Can anybody please help me out. I am writin...

## the traceback depth of viterbi decoder in simulink

Started by in comp.dsp15 years ago

Dear All, Now I face a problem about the traceback depth of viterbi decoder. For an example, the convolutional code with coding...

Dear All, Now I face a problem about the traceback depth of viterbi decoder. For an example, the convolutional code with coding rate 5/8(the mother rate is 1/3, puncture vector is [1 0 1 1 0 0 1 0 1 0 0 1 1 0 1]), constraint length K=7. I use the Bernoulli Binary Generator as the signal source to generate a column vector with the size 125*1(frame_based), after the 5/8 encoder, the ...

## looking for help on sofe demodulate and soft-input Viterbi decode

Started by in comp.dsp14 years ago 4 replies

is there any article or paper that describe the detail algorithm of soft demodulate and soft-input viterbi decode? Thank you!

is there any article or paper that describe the detail algorithm of soft demodulate and soft-input viterbi decode? Thank you!

## Viterbi decoder - full traceback or K x Y?

Started by in comp.dsp13 years ago 6 replies

Hi, Can someone explain fact that for longer messages a traceback depth of K x Y, where K is constraint length of convolutional encoder, and if...

Hi, Can someone explain fact that for longer messages a traceback depth of K x Y, where K is constraint length of convolutional encoder, and if Y increases, then ok we could say that decoding delay and decoder memory requirements increases, while not significantly improving the performance of the decoder. But, if we use full-traceback (i.e. best performance) Viterbi decoder, we need to built la...

## Viterbi Soft Decision for 16FSK

Started by in comp.dsp16 years ago 4 replies

Hi, I need to build a Viterbi for 16FSK. 1/2 with K=7. In the case of BFSK, Soft Decision is not a problem for me, I compare...

Hi, I need to build a Viterbi for 16FSK. 1/2 with K=7. In the case of BFSK, Soft Decision is not a problem for me, I compare the correlation for a symbol '0' and for a symbol '1' and i know the confidence for '0' o for '1'. In the case of 16FSK, i am lost, because a symbol has 4 bits that belong to a same frecuency. For example: "0000" belong to a tone of 1000 Hz For example: "0001...

## Viterbi 'synchronization'?

Started by in comp.dsp15 years ago 9 replies

Hello, this is almost a philosofical questions, but I couldn't find an answer on the web, so I'm asking here. I am trying to decode a...

Hello, this is almost a philosofical questions, but I couldn't find an answer on the web, so I'm asking here. I am trying to decode a stream of convolutionary coded symbols (R=1/2; K=7) with Viterbi and everything runs fine. The encoded makes from one bit two symbols, so the encoded stream contains these alternating symbols (1st, 2nd, 1st, 2nd, 1st, 2nd, etc.). When I pass the stream t...

## Viterbi decoder's error correction/noise tolerance capability

Started by in comp.dsp16 years ago

Hi: Can someone explain to me the meaning of the statement "The noise tolerance of a Viterbi decoder is x dB"? Is noise tolerance the same...

Hi: Can someone explain to me the meaning of the statement "The noise tolerance of a Viterbi decoder is x dB"? Is noise tolerance the same as BER (as measured in the form 10^(-y))? How are these 2 quants related? I am using a soft demapper that takes in 16 bit input to generate 4 single-byte "soft" inputs per iteration, which are then passed pair wise through a soft input/hard output ...

## Sliding window Viterbi

Started by in comp.dsp17 years ago 7 replies

I am using a homemade Viterbi decoder to remove ISI. Originally, my decoder maintained path history (states vs time) for the entire duration of...

I am using a homemade Viterbi decoder to remove ISI. Originally, my decoder maintained path history (states vs time) for the entire duration of the message (1e5 bits) and it traced all the way back from end to finish. Then I modified it to use a sliding window. I created a circular buffer equal to the desired traceback length (about 5 times the ISI duration) and kept the path history in that ...

## Soft-decision viterbi implementation

Started by in comp.dsp13 years ago 8 replies

Hi all, I want to implement soft decision viterbi decoder in FPGA. I have already implemented hard-decision decoding and the design works fine...

Hi all, I want to implement soft decision viterbi decoder in FPGA. I have already implemented hard-decision decoding and the design works fine in xilinx FPGA. We have implemented "high bit clear circuit" for path metrics normalization to reduce the area. Now, i want to implement soft-decision decoding an I need to change the BMU and ACS modules in my code. One thing that worries me is the ...