Re: CCSDS 27 encoder/decoder

[George Edwards]

Thanks very much Christophe! George

On Mon, Apr 19, 2021, 2:16 PM Christophe Seguinot <christophe.seguinot@orange.fr> wrote:

Hi

comparing inp and out bits in x-PSK at least need differential encoding/decoding,

See for example https://wiki.gnuradio.org/index.php/Guided_Tutorial_PSK_Demodulation

Regards,

On 19/04/2021 00:48, George Edwards wrote:

Hello Gnuradio Community,

I am working with the Gnuradio CCSDS 27 encoder/decoder blocks in Gnuradio ver 3.8. To ensure I understand these blocks, I fed a random signal from  0-255 into the encoder with an embedded Python block between the encoder and decoder which converts the bit values 0 and 1 leaving the encoder into -1 and +1 for the decoder. I use file sinks to collect the byte values (between 0-255) entering the encoder and collect those leaving the decoder and compare them to validate proper working functioning. Works good!!! 

Next, appropriate blocks comprising QPSK modulator/demodulator were inserted between the CCSDS 27 encoder/decoder. At this point I could not get the output of the decoder to equal to the input of the encoder. I have tried everything, the latest being the decomposition of data (input and output) down to the bit level and put in a delay to see if I can find synchronization between the input and output bit values. I have attached my grc flowgraph.

I will appreciate any help.

Regards,

George