Questions tagged [viterbi-algorithm]

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Understanding Baum's auxiliary function used in Hidden Markov Model

I am studying HMM from "Fundamentals of Speech Recognition" by Rabiner. Regarding the problem of how to adjust the parameters of a HMM, the proposed method was Baum Welch method (Expectation-...
Anantha Krishnan's user avatar
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Exact computation cost using Forward Procedure for HMM probability evaluation

I am understanding the HMM concept for Speech Recognition. One of the three problems (HMM) to be solved is Probability evaluation $P(O|\lambda)$. Instead of a straightforward approach which is ...
Anantha Krishnan's user avatar
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Maximum Likelihood for Colored Noise: Implementing using Viterbi Algorithm

I have a question regarding the ML estimation in presence of colored noise, i.e., Additive Colored Gaussian Noise. I want to implement this using a Viterbi algorithm, since I need to take the '...
Jacob's user avatar
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-1 votes
1 answer
237 views

Viterbi decoder K=3 using ADD-COMPARE-SELECT Operation

I am in trouble with Viterbi decoder for a while. I have some questions. I need to decode messages from a continuous stream which is encoded. I'm reading from book : digital communications bernard ...
Maher's user avatar
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2 votes
2 answers
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GnuRadio CC Decoder or How to use FEC Extended Decoder

I am currently trying to recover a satellite signal, encoded following CCSDS standards. This includes a convolutional code with rate 1/2 and constraint length 7. I am receiving the signal through an ...
valkyrie's user avatar
4 votes
1 answer
277 views

Help understanding ka9q viterbi27 streaming operation

I'm working to implement a k=7, r=1/2 convolutional code and Viterbi decoder for forward error correction. I want to operate in streaming mode, so that can pull data from the stream before the entire ...
harry courtice's user avatar
2 votes
0 answers
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Problem with 1st order PLL update equation

The output of a communication channel is given by: $x(t) = \sum_n{a_n}h(t-nT)$, where $\{a_n\}$ are BPSK symbols, $h(t)$ is the channel response, and $T$ is the symbol period. If there is an ...
Elnaz's user avatar
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117 views

How to detect missing bit position in a bit-stream?

I'm trying to establish a one-way communication and facing problem in the receiver end because of some missing bits. For example, if the sender sends 100 bits the receiver received 95/96 bit. Now the ...
perplex's user avatar
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3 answers
412 views

Why does the flat part of the BER curve appear after the Viterbi decoder (MatLab)?

I am trying to implement convolutional codes according to this MathWorks example in MatLab 2014a. ...
vovenur's user avatar
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1 vote
0 answers
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convolutional coding with higher order QAM

I've implemented a simple 1/2 rate convolutional code and a viterbi decoder algorithm. I followed the most-common type of convolutional coding implementation I could find by googling: 1 input bit gets ...
user2913869's user avatar
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Trellis-converging offset and the min-sum algorithm

I am going through a paper on the design of interleavers for Turbo codes and I am a little bit confused about how to calculate what they call Trellis-Converging offset. They define such parameter of a ...
Josu Etxezarreta Martinez's user avatar
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Viterbi Algorithm - Selecting survivor paths which both contain the same Hamming distance

To my (limited) knowledge, when determining which survivor path to choose to produce an error-corrected output of a binary Viterbi decoder, the path with the smallest Hamming distance is the most ...
C. Faldon's user avatar
1 vote
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150 views

Convolutional FEC decoding - is it necessary to know where a decoding block begins and ends with convolutional codes?

I understand that the difference between convolutional and block-based FEC is that convolutional codes can be used in a continuous stream – however every implementation I saw still uses blocks. So I ...
Mara Ara's user avatar
1 vote
0 answers
70 views

Viterbi equalization of Fibonacci coding

I'm working a Viterbi equalizer for a BPSK signal which uses Fibonacci coding. In the more theoretical descriptions of the Viterbi algorithm I've read, there's a term for the probability of a ...
Phil Frost's user avatar
3 votes
1 answer
340 views

Determining pulse shape for Viterbi Equalization

I believe I understand well enough how the Viterbi algorithm can reverse the effects of ISI when the combined impulse response (transmit filter, multipath, receive filter) is known. I've read How I ...
Phil Frost's user avatar
3 votes
1 answer
486 views

Applying Viterbi algorithm to compensate for ISI in PSK31

I am implementing a receiver for the amateur radio mode PSK31. It is effectively a BPSK modulation with a pulse shape of a raised cosine twice the width of one symbol. Here are four consecutive pulses,...
Phil Frost's user avatar
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1 answer
250 views

Viterbi Decoder without traceback

How can I use Viterbi algorithm for a real time scenario where I cannot afford to have delay in the tracing back the best path to the initial state?
Sumbul's user avatar
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2 votes
1 answer
432 views

Decoding final bits with viterbi

I'm writing a viterbi decoder and I'm rather confused about the correct process of decoding the final k bits for a kth order ...
Brian Armstrong's user avatar
1 vote
0 answers
99 views

State definition in Viterbi Algorithm?

An ISI channel of length 'L+1' $\mathbf{h}=[h_0 \space h_1 \space … \space h_L]$can always be modeled as a finite state machine(FSM) of memory 'L'. For a binary input $x\in\{+1,-1\}$,a state can be ...
NAASI's user avatar
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2 votes
1 answer
123 views

Performance of Viterbi detector over non-minimum phase channels

For sequences that are transmitted over channels with memory $\mu=n$ and response H=$[h_0 h_1 \ldots h_n]$,Viterbi algorithm implements Maximum Likelihood (ML) detection and BCJR implements Maximum A-...
NAASI's user avatar
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2 votes
0 answers
409 views

Viterbi Decoder=1/2 k=4 [closed]

Woud anyone have a viterbi decoding tool or c-code or .m file for (R=1/2, K=4)? I am trying to decode a bitstream received in RFSTUDIO from a non-TI transceiver and it says that it uses this kind of ...
Vangelis El Vagor's user avatar
3 votes
2 answers
1k views

Viterbi equalizer in a GSM system

I'm about to tackle implementing a Viterbi equalizer fo a GSM system in gnuradio. I went through the internet and ieeexplore and I think that this document explains it best: Application of Viterbi ...
Mehow's user avatar
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2 votes
0 answers
83 views

Does the input data have to be passed through the Baum-Welsh function to compute the Viterbi decoder?

I'm using a Hidden Markov Model in order to train an application for gesture recognition. Currently, I have gathered samples, and, using a library have trained these values (They have been passed ...
Phorce's user avatar
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4 votes
1 answer
4k views

QPSK soft decoding

I'm trying to decode a Hamming Block Code transmitted using a QPSK modulation. For the moment I can sucessfully decode it using hard decision but in order to improve performance I'd like to use soft ...
Leo's user avatar
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2 votes
0 answers
309 views

Most efficient algorithm for comparing two paths

I'm working with a Continuous Hidden Markov Model, and using the Viterbi Decoder which finds the best possible path for a given sequence. Here is how my algorithm works: ...
Phorce's user avatar
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2 votes
1 answer
571 views

Viterbi Decoder - How does inverting the input bits affect the result?

Does converting zeros into ones and ones into zeros in the input stream affect the decoding result? Empirically I have seen that it does not affect, decoding $[0 1 0 1 \ldots]$ and $[1 0 1 0 \ldots]$ ...
groove's user avatar
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