Re: [Discuss-gnuradio] Error in "Constellation Decoder" block

[Tom Rondeau]

On Tue, Mar 4, 2014 at 4:17 PM, Azza Ben Mosbah
<address@hidden> wrote:
> Hi All,
>
> I am manipulating GNU Radio Companion.
> While using the "Constellation Decoder" block, I have put
> digital.constellation_qpsk as a "Constellation Object" argument. But, I have
> found an error when I have executed the flow graph:
>
> Traceback (most recent call last):
>   File "/users/anb10/metrics/error_rate.py", line 342, in <module>
>     tb = error_rate()
>   File "/users/anb10/metrics/error_rate.py", line 225, in __init__
>     self.digital_constellation_decoder_cb_0 =
> digital.constellation_decoder_cb(digital.constellation_qpsk)
>   File
> "/usr/lib64/python2.6/site-packages/gnuradio/digital/digital_swig.py", line
> 3096, in constellation_decoder_cb
>     return _digital_swig.constellation_decoder_cb(*args, **kwargs)
> TypeError: in method 'constellation_decoder_cb', argument 1 of type
> 'digital_constellation_sptr'
>
> I don't know what went wrong. I have even tried
> digital.psk.psk_constellation(m=4,mod_code='gray'),
> digital.constellation_8psk and
> digital.psk.psk_constellation(m=8,mod_code='gray') as a "Constellation
> Object" argument.
>
> So, what is the proper way to define the argument (Constellation Object) in
> the "Constellation Decoder" block?
>
> I hope you can give me some ideas. Any help is appreciated. Thank you.
>
> Regards,
> Azza

Azza,

Check out the documentation page:
http://gnuradio.org/doc/doxygen/classgr_1_1digital_1_1constellation__decoder__cb.html

It's not entirely clear (unless you know to look for it). You want to
pass the constellation object using the base() parameter to get to the
parent class.  Basically, you'd call it:

digital.constellation_decoder_cb(digital.constellation_qpsk.base())

Tom