[Discuss-gnuradio] Decoding CCSDS

[Michael Sabino]

On 1/30/16, Michael Sabino <address@hidden> wrote:
> I'm going to post my flowgraph. I have added a CCSDS decoder block.
> Please, if you can, provide input on how to improve the amount of
> successfully decoded data with a short wave file and a doppler
> shifting BPSK carrier.
>
> My .wav file: http://1drv.ms/1bS3KxX
>
> and here is my gnuradio flowgraph: http://1drv.ms/1m3o3N6
>
> Using several different decoding methods, I have obtained strings
> found in these two documents:
>
> http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19880002723.pdf
> http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19800022222.pdf
>
> (for the Aeronomy of Ice in the Mesosphere spacecraft). One is old
> NASA teleoperator system reference, if that helps.
>
> However, the gnuradio method (I was also using a seperate program
> written for an SDR analysis/display utility called SDR#/SDRSharp), is
> presently suboptimal.
>
> I have some times where I see a BPSK constellation, but other times
> (some in between the good constellations) I just see a ring where it
> loses synchronization. Please provide help on how to improve my BPSK
> demodulator.
>
> Thanks
>
> Michael Sabino
>
> On 1/27/16, Achilleas Anastasopoulos <address@hidden> wrote:
>> The problem is not the length 2048 but the way you use the fsm
>> constructor
>>
>> trellis.fsm(2,7,[79,109])
>>
>> You are trying to create an FSM for a (7,2) CC.
>>
>> This means you need to provide a vector of 2x7 integers, each
>>
>> representing the generator polynomial between the i-th input (i=0,1)
>>
>> to the j-th output (j=0,1,...,6)
>>
>>
>> However you only provide 2 of them.
>>
>>
>> Are you sure this is what you want to do?
>>
>> ------------
>>
>> this is a snippet from fsm.cc
>>
>>
>> //######################################################################
>>     //# Automatically generate the FSM from the generator matrix
>>     //# of a (n,k) binary convolutional code
>>
>> //######################################################################
>>     fsm::fsm(int k, int n, const std::vector<int> &G)
>>
>