Re: [Discuss-gnuradio] OFDM GRC block attempt

[jcorgan]

The conversion of all the example code and blks code on the trunk to the new 
3.1 flow graph code is nearly complete.

This is being done in the jcorgan/t162 developer branch if you want to take a 
look.

Once this is merged into the trunk, you'll be able to restore GRC functionality.

Sent via BlackBerry by AT&T

-----Original Message-----
From: Josh Blum <address@hidden>

Date: Fri, 14 Sep 2007 20:34:40 
To:Dev Ramudit <address@hidden>
Cc:address@hidden
Subject: Re: [Discuss-gnuradio] OFDM GRC block attempt


In short, the GRC code for the packet modulator was no good after the 
"incompatible trunk check in". So, I just deleted the packet mod/demod 
code in GRC.

To restore the functionality of the packet mod/demod (in grc), i would 
have to cannibalize the current blks.pkt code. I will be glad to do 
this, especially if someone is using the blocks.

The only thing about the packet mod/demod blocks is that they are 
implemented poorly. For example, to implement a packet modulation block, 
you have to sample the gnuradio stream with a message sink and a thread, 
the error coding/packetizing is done in python with packet utils, and 
then the data is pushed back into the gnuradio stream with a message 
source. Not too efficient. Any suggestions before I go ahead with the 
message source/sink idea?

Anyway, it would be great to get ofdm working with GRC.

-Josh



Dev Ramudit wrote:
> Hello all,
> 
>       I'm trying to write an OFDM mod/demod for the gnuradio companion and
> I'm running into a problem. I'm following the (now deprecated?) packet
> modulator code that was in GRC very closely. I have an OFDMDemod block
> which creates the following class when its used:
> 
> ---
> 
> class OFDMDemodHelper(gr.hier_block2):
>       """Forward data from ofdm demod to the gr data stream."""
>       def __init__(self, item_size, options):
>               #create hier block
>               gr.hier_block2.__init__(
>                       self, 'ofdm_demod',
>                       gr.io_signature(1, 1, Complex().get_num_bytes()),
>                       gr.io_signature(1, 1, item_size)
>               )
>               #the message source (handles the output data stream)
>               msg_source = gr.message_source(item_size, DEFAULT_QUEUE_LIMIT)
>               msgq = msg_source.msgq()
>               def callback(ok, payload):
>                       if ok: msgq.insert_tail(gr.message_from_string(payload, 
> 0, item_size,
> len(payload)/item_size))
>               ofdm_demod = blks.ofdm_demod(
>                       fg=self,
>                       options=options,
>                       callback=callback,
>               )
>               #connections
>               self.connect(msg_source, self)
>               self.connect(self, ofdm_demod.head)
> 
> ---
> 
> This is basically the same as the old packet demod code, with a few
> small changes for OFDM. Unfortunately, I get the following error:
> 
> ---
> 
>  File "/home/dramudit/work/gnuradio/grc/src/SignalBlockDefs/Packet.py",
> line 337, in __init__
>     callback=callback,
>   File
> "/usr/local/lib/python2.4/site-packages/gnuradio/blksimpl/ofdm.py", line
> 218, in __init__
>     options.log)
>   File
> "/usr/local/lib/python2.4/site-packages/gnuradio/blksimpl/ofdm_receiver.py",
> line 56, in __init__
>     self.fg.connect(self.chan_filt, self.ofdm_sync)
>   File
> "/usr/local/lib/python2.4/site-packages/gnuradio/gr/hier_block2.py",
> line 46, in connect
>     self._connect(points[i-1], points[i])
>   File
> "/usr/local/lib/python2.4/site-packages/gnuradio/gr/hier_block2.py",
> line 50, in _connect
>     (dst_block, dst_port) = self._coerce_endpoint(dst)
>   File
> "/usr/local/lib/python2.4/site-packages/gnuradio/gr/hier_block2.py",
> line 61, in _coerce_endpoint
>     raise ValueError("unable to coerce endpoint")
> ValueError: unable to coerce endpoint
> 
> ---
> 
> Any suggestions as far as fixing this error, or another approach?
> 
> Thanks,
> Dev
> 
> 
> _______________________________________________
> Discuss-gnuradio mailing list
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> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> 



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