[Discuss-gnuradio] RE: Re: Complex samples format with ASK

[C.cc Jay]

Hello Marco

  (1) You use an opt. filter to get the passband from 400kHz to 410kHz.
      your message is on frequency 4** kHz?

  (2) After I run your code, I got different error (GUI error)
      on
      File "usrp_am_mw_rcv_002.py", line 309, in set_freq
      self.update_status_bar()
      File "usrp_am_mw_rcv_002.py", line 321, in update_status_bar
      msg = "Volume:%r  Setting:%s" % (self.vol, self.state)

      if I remark this two line. give up update_status_bar() then,
      the error is the same as yours.

      I guess, the problem is in
      self.connect (self.u, self.chan_filt, self.am_demod) <-
      Do you try to connect some sink block after self.am_demo
such like scopesink.scope_sink_f


   (3)
      Matlab? I didn't try my USRP on Matlab.
      Q: work in time domain or in the samples domain?
      The code is on time domain, isn't.

   (4)
   In Paul says:
>> There are better ways, e.g., using matched filters, to identify
>> Manchester codes directly from the envelope data, but this should get you
>> started.

   I prefer to use matched filter, but i also got another different 
question.
   How do i know, the package start. hmm... I need more and more study!!

CJay

Marco Bottino wrote:
> I am trying to understand how to modify usrp_am_mw_rcv.py code:
> I have eliminated everything inherent the volume and the audio and I 
> have
> modified the parameters in that way:
> 16 as usrp_decim
> 1 as chanfilt_decim
> 
> chan_filt_coeffs:
> 400e3 as passband cutoff
> 410e3 as stopband cutoff
> 1.0 as passband ripple
> 60 as stopband attenuation
> 
> Is it correct?
> (To be more clear I have attached the .py modified file)
> I think I'll still have some troubles with the GUI, but so far this is 
> the
> message error I got:
> 
> address@hidden:~/Desktop# ./usrp_am_mw_rcv_002.py -R B -f 13560000
> Using RX d'board B: LF Rx
>>>> gr_fir_ccf: using SSE
> 
> ... 
> "/usr/local/lib/python2.5/site-packages/gnuradio/gr/gnuradio_swig_py_runtime.py",
> line 1461, in start
>     return _gnuradio_swig_py_runtime.gr_top_block_sptr_start(*args)
> RuntimeError: complex_to_mag(4): insufficient connected output ports (1 
> needed,
> 0 connected)
> 
> 
> 
> 
>> coupling with the reader, like this:
>>
>>
>>        ___     ___    ___
>>       |   |___|   |__|   |
>>  0 ___|                  |___
>>
>> In either case, you can threshold the data at some value less than the
>> average peak to do a crude conversion from envelope to bits. In turn, you
>> can examine the bitstream to locate bit transitions. The bit stream can then
>> be decoded.
> 
> Here I have another question: at the moment I am trying to do that in 
> Matlab
> because of my so much inexperience in programming with Gnuradio. My 
> problem is
> to recognize the length of the bits... Once I have converted the I/Q 
> samples in
> magnitude, do I have to work in time domain or in the samples domain? 
> (to be
> more clear, counting the microseconds or counting the number of the 
> samples to
> identify a bit period?)
> 
> 
>> There are better ways, e.g., using matched filters, to identify
>> Manchester codes directly from the envelope data, but this should get you
>> started.
>> Paul Mathews
>>
>>
>>
> 
> Thank you very much,
> 
> Marco

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