Re: [Discuss-gnuradio] trellis encoder and OFDM modulator

[vanITA1082]

Did you solve it?

I am trying to add FEC in the OFDM chain but I didn't figure out how to do
this, yet.

Any advice or do you know if someone did it and the code is public?

Thanks

Veljko Pejovic wrote:
> 
> Hi,
> 
> I tried to use trellis_encoder from trellis package to perform
> convolution coding before sending the message to the OFDM modulator.
> However, ofdm_mod has zero input signature, and relies on send_pkt()
> which calls ofdm_packet_utils.make_packet() and then puts the message
> in the queue at gr.ofdm_mapper_bcv. Since the chain basically starts
> with ofdm_mod I don't see the way to connect the trellis_encoder
> before the signal is already modulated. In ftw80211 project they
> modify ofdm_packet_utils and write their own convolution coding
> method, I could do the same, but then I would miss all the benefits of
> this nice trellis package.
> 
> Interestingly, the other modulation blocks such as dbpsk or d8psk have
> different input signatures, and I would put the trellis_encoder
> between the gr.message_source and modulator in pkt.py. Is there a way
> to seamlessly introduce trellis_encoder in the flow graph with an OFDM
> modulator? Am I missing something here?
> 
> 
> Thanks,
> 
> 
> Veljko
> 
> 
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> 
> 

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