Re: [Discuss-gnuradio] Frequency Hopping

[Firas A.]

Hi,

Good project. If you successes, give us a feedback.

BTW, you can shift your TX and RX frequencies by using set_tx_freq() and
set_rx_freq() (if you are using Basic TX and RX boards)

Best Regards,

Firas




Attari wrote:
> 
> Hi!
> I am implementing freq hopping in gnu radio. My system is like
> 
> information bits ----> BPSK Mod------> Mixer ----->D/A------>Transmit over
> USRP
> 
> I am shifting my base band spectrum of my information by multiplying it
> with an exp(jw). to implement this mixer i change dbpsk.py file by
> inserting an exp(jw) at the end of rrc filter like in this sample code:
> 
>         Cosine = gr.sig_source_f(250e3,gr.GR_COS_WAVE,self._mix_freq,1,0)
>       Sin    = gr.sig_source_f(250e3,gr.GR_SIN_WAVE,self._mix_freq,1,0)
> 
>       self.expjw = gr.float_to_complex()
>       self.connect(Cosine,(self.expjw,0))
>       self.connect(Sin,(self.expjw,1))
> 
>       self.mixer = gr.multiply_cc()
>       self.connect(self.rrc_filter ,(self.mixer,0))
>       self.connect(self.expjw ,(self.mixer,1))
>       
>       # Connect
>       print "\nConnect() of dbpsk.py file Asad \n"
>       print verbose
>         self.connect(self, self.bytes2chunks, self.symbol_mapper,
> self.diffenc,
>                      self.chunks2symbols, self.mixer, self)
> 
> ###########################
> 
> I am passing mixer frequency (As it is set in controller and my controller
> is benchmark_tx.py) in benchmark_tx.py file to transmit_path.py . I am
> getting following error :
> 
> 
> Traceback (most recent call last):
>   File "./benchmark_tx_var.py", line 163, in <module>
>     main()
>   File "./benchmark_tx_var.py", line 104, in main
>     tb = my_top_block(mods[options.modulation], options, Ctrl_mixer_freq)
>   File "./benchmark_tx_var.py", line 42, in __init__
>     self.txpath = transmit_path(modulator, options, Ctrl_mixer_freq)
>   File
> "/usr/src/gnu/gnuradio-3.1.2/gnuradio-examples/python/digital/transmit_path.py",
> line 86, in __init__
>     blks2.mod_pkts(self._modulator_class(**mod_kwargs),
>   File
> "/usr/local/lib/python2.5/site-packages/gnuradio/blks2impl/dbpsk.py", line
> 134, in __init__
>     self.chunks2symbols, self.mixer, self)
>   File
> "/usr/local/lib/python2.5/site-packages/gnuradio/gr/hier_block2.py", line
> 70, in connect
>     self._connect(points[i-1], points[i])
>   File
> "/usr/local/lib/python2.5/site-packages/gnuradio/gr/hier_block2.py", line
> 76, in _connect
>     dst_block.basic_block(), dst_port)
>   File
> "/usr/local/lib/python2.5/site-packages/gnuradio/gr/gnuradio_swig_py_runtime.py",
> line 946, in connect
>     return _gnuradio_swig_py_runtime.gr_hier_block2_sptr_connect(*args)
> ValueError: destination already in use by edge
> interp_fir_filter_ccf(8):0->multiply_cc(12):0
> 
> 
> i am stuck in this place. kindly help me. 
> 
> 

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