Re: [Discuss-gnuradio] Receiving errors with Viterbi decoder block/Decoding AIM spacecraft

[Michael Sabino]

I abandoned the FSM constructor and decided to just use the decode
CCSDS27 block.


Michael

On 1/30/16, Achilleas Anastasopoulos <address@hidden> wrote:
> Michael,
>
> I haven't seen your flowgraph, but as I wrote in my previous email you are
> using the fsm constructor probably in the wrong way:
>
> You are confusing the (n,k,K) parameters of a CC.
> k = number of input bits per period
> n = number of output bits per period
> K = constraint length of the code (related to the memory it requires)
>
> If you want to build a (2,1,*) CC then you need to call the fsm constructor
> with these two numbers AND a vector of 2x1=2 integers representing the two
> generator polynomials.
> (If you think about it the constraint length parameter need not be input to
> the constructor because it can be derived from the generator polynomials)
>
>
>
> *fsm::fsm(int k, int n, const std::vector<int> &G)*
>
> so in the above example it should be something like
>
>
> *fsm(1,2, *
>
>
> *[79,109])*
>
> On the other hand, i don't know if this is what you want to do.
>
> If you tell us the exact parameters of the code you want to build I
> would be able to help more.
> (the rate of the code 1/2 that you gave in your previous email is not
> sufficient, because R=1/2=2/4 so a (4,2,*)
> CC will also have the same rate but it would require you to provide 4
> x 2 =8 generator polynomials to construct it).
>
>
> Achilleas
>