A problem of the turbo channel coding!

GNU Radio
1

Hi, all

     Currently, I am trying to establish a data transmission system

using the Viterbi coding method as the channel coding.

     I found a problem that the output of the coding module is short

type,

     Enc = trellis.encoder_ss(f, 0)



     While the decode module needs a float type

     Va = trellis.viterbi_s(f, K, 0, -1)



     Can some one tell me how to make them compatible?

Thanks

Shucai

2

On Fri, Sep 12, 2008 at 8:37 AM, Shucai X. [email protected] wrote:

     Enc = trellis.encoder_ss(f, 0)



     While the decode module needs a float type

     Va = trellis.viterbi_s(f, K, 0, -1)



     Can some one tell me how to make them compatible?

The encoder works on hard data bits that you want to transmit over the
air.

The decoder works on soft decision bits that you have received.

Scale your encoder bits to be within the soft decision range.

Brian

3

Thanks for your response.

I have another problem that, if the USRP board is used in the system and
the
GMSK modulation is used, what kind of channel coding module can be used,
and
where should we insert the channel coding, before the GMSK module or
after
the GMSK?

Thanks a lot

Shucai

4

Also, if there is any existing channel encoding/decoding modules that
use
short/char as input and use the same type as the output, too?

Thanks

Best regards

Shucai

5

2008/9/12 Shucai X. [email protected]:

Thanks for your response.

I have another problem that, if the USRP board is used in the system and the
GMSK modulation is used, what kind of channel coding module can be used, and
where should we insert the channel coding, before the GMSK module or after
the GMSK?

I’m having a hard time following your question.

What exactly are you trying to do?

Brian