Decoding Convolutional Codes: The Viterbi Algorithm Explained

[@navodsuraweera]

Hi Iain, your videos including this one helped me a lot to refresh my comms. and signals knowledge to prepare for my job interview. Many thanks for that. You are doing a wonderful job.

[@iain_explains]

Thanks Navod, that's great to hear. I'm really glad the videos have been helpful.

[@thebananaspin]

Hi Ian, thanks a lot, this helps in my self study of soft decoding and ldpc decoding.

[@iain_explains]

Glad it helped! This video might also help: "Viterbi Algorithm Explained with an Example" kzbin.info/www/bejne/rqnTc3t5oN6jiZY

[@rheniuspaul389]

Very helpful sir 🎉

[@iain_explains]

Glad to hear that.

[@johndunn5272]

If I say anything then I could be decoded. What you need too see is this is like Pine Gap in education. But then it would imply that there is deception intelligence in engineering and the education. Then there's espionage in job allocations and position fitting a person's role. Maybe the NASA educational stance is the way to go to avoid building another espionage empire with engineering and education into the money stream. Basically at some point lower voltage operations and higher frequency transmissions equate to increased complexity in decoding in noise. Maybe there's a practical limit since you can't miniaturize Pine Gap below Moore's Law in which case it's Quantum communications instead of a noise floor for intelligence in error correction. Sorry if I'm a little hard to understand....but you were not to clear yourself. But your genuineness is appreciated...

[@guilhermegomes1314]

great video! I'd like to point a possible mistake, I think you swapped the possible outputs of the states 01 and 10 (assuming the bits are represented in the same way as they look in the boxes)

[@iain_explains]

Let's take the line that joins the 00 state (on the left of the transition) to the 10 stat (on the right of the transition). For this line, the contents of the three-element shift register in the encoder are 100. This is because the "state" is defined as the contents of the central element, and the right hand element of the shift register - and for this line in the trellis, the current state is 00, and the next state is 10. This means the output will be 101, if you trace along the lines for the three outputs.

[@guilhermegomes1314]

@@iain_explains thanks! it was I who confused myself here, you're right 👍🏻

[@Oshea73]

can you do a video on communication codes like turbo codes bcjr ldpc decoding visualized thanks

[@iain_explains]

Thanks for the topic suggestion. I've got it on my "to do" list.

[@sadeqebrahimi2925]

Polar coding and decoding pleas

[@iain_explains]

Thanks for the suggestion. It's on my "to do" list.

[@abdullahibrahimi3419]

I subscribed your channel and I like your videos and appreciate your work, but indeed this explanation is soo poor. I know trellis diagram very well and the states and transitions but i wanted to learn how decoding works but unfortunately i didn't get.

[@iain_explains]

Yeah, well, it's a hard topic and it's not easy to explain. I'm planning to do another video with a numerical example. Hopefully that will help.

[@iain_explains]

Hi Abdullah, I've made a new video where I've tried to explain the Viterbi Algorithm more directly, using the actual update equation, and showing how it relates to the trellis. I hope this helps: "Viterbi Algorithm Explained with an Example" kzbin.info/www/bejne/rqnTc3t5oN6jiZY

[@analysislearning9179]

complicated

[@iain_explains]

The steps of the algorithm itself are simple, but it's complicated to visualise what's going on, and why it works. I might have another go at explaining it in another video.

[@analysislearning9179]

@@iain_explains you are the best

[@iain_explains]

I've made a new video where I've tried to explain the Viterbi Algorithm more directly, using the actual update equation, and showing how it relates to the trellis. I hope this helps: "Viterbi Algorithm Explained with an Example" kzbin.info/www/bejne/rqnTc3t5oN6jiZY

[@chanvu1077]

Your solution is not clear and complicated to understand

[@marcoponts8942]

Did you watch the previous video in the series where he explains the convolutional code? Might help. I do agree though that an explanation of how the path metric is evaluated had been useful. :)

[@sadeqebrahimi2925]

I dont understand this lecture and the next one

[@iain_explains]

I agree it's definitely a complicated topic. I think I'll try to make another video where I work through a numerical example.

[@Pep95]

@@iain_explains How do I know I only have to consider the signals ending up at 00? Or is that a simplification?

[@Loki-je3oj]

@@Pep95 I think that is just a simplification, it seems to me the process which he described for deciding which path should be taken to the 00 state (the one far right) is actually the same process which the algorithm is using for each one of the states (and each time it has a longer bit sequence to compare to the expected output)