RE: [Discuss-gnuradio] A problem of the turbo channel coding!

[Shucai Xiao]

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

-----Original Message-----
From: Brian Padalino [mailto:address@hidden 
Sent: 2008年9月12日 8:54
To: Shucai Xiao
Cc: address@hidden
Subject: Re: [Discuss-gnuradio] A problem of the turbo channel coding!

On Fri, Sep 12, 2008 at 8:37 AM, Shucai Xiao <address@hidden> wrote:
> 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?

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