Re: [Discuss-gnuradio] Tx/Rx using one USRP board

[Eric Blossom]

On Wed, Aug 01, 2007 at 05:52:56AM +0100, pratik hetamsaria wrote:
> hi,
> 

> I am posting this again as i havent got any concrete replies.I have
> been stuck making the usrp work as a relay for a very long time. I
> am giving the code which i am using for making it work as a
> relay. Can somebody please point out where is the mistake. I am
> trying to receive a signal sent by usrp_siggen.py at 910MHz and
> retransmit it at 950MHz. However, when i view the signal at 950MHz
> using usrp_oscope.py then i am able to see only noise. There is no
> sine wave present at that frequency. I am not able to understand
> what is the usrp transmitting at 950 MHz then. What i know is that
> the usrp does receive the sine wave at 910MHz.

Are you using one or two daughterboards?

What kind of daughterboard(s)?

Is your rx-subdev-spec the same as tx-subdev-spec?

Checking to see if r is None is highly recommended.

If you're using a RFX-900 for TX, is the saw filter still in?
(It comes with a 902 to 928 MHz ISM band filter.)

Does the data in usrp_data_receive.dat look reasonable?
What are the min and max values that you see?

What's your tx-amplitude?

Depending on the tx daughterboard, you may need

  dst.set_enable(True)

If you're trying to use a single RFX-* daughterboard, you'll need to
set the RX to receive from the RX2 antenna port, not the TX/RX port:

  rx_src.select_rx_antenna('RX2')
  

Eric


> PLease point out where is the mistake in my code.
> 
> Thanks
> Pratik Hetamsaria
> 
> _________________________________________________________________
> 
> class my_graph(gr.flow_graph):
> 
>     def __init__(self):
>         gr.flow_graph.__init_ _(self)
>     
>     parser = OptionParser(option_class=eng_option)
>         parser.add_option("-R", "--rx-subdev-spec",  type="subdev", 
> default=None)
>         parser.add_option("-d", "--decim", type="int", default=256)           
>         
>         parser.add_option("-f",  "--freq", type="eng_float", default=910e6)
>         parser.add_option("-g", "--gain", type="eng_float", default=45)
>         parser.add_option("-T", "--tx-subdev-spec", type="subdev", 
> default=None) 
>         parser.add_option("-a", "--tx-amplitude", type="eng_float", 
> default=32000)
>         parser.add_option("-q", "--tx-freq", type="eng_float", default=950e6) 
>         parser.add_option("-i", "--interp", type="intx", default=512)
>         (options, args) =  parser.parse_args()
> 
>     rx_src = usrp.source_c (0, options.decim)
>     rx_subdev_spec = (0,0) 
>     rx_src.set_mux(usrp.determine_rx_mux_value(rx_src, rx_subdev_spec))
>     subdev = usrp.selected_subdev(rx_src,  rx_subdev_spec)
>     r = rx_src.tune(0, subdev, options.freq)
>     
>     self._tx_amplitude = options.tx_amplitude
>     self.amp = gr.multiply_const_cc(0)
      self.amp.set_k(self._tx_amplitude)
>
>     dst = usrp.sink_c(0, options.interp)
>     if options.tx_subdev_spec is None:
>             tx_subdev_spec = usrp.pick_tx_subdevice(dst)
>      dst.set_mux(usrp.determine_tx_mux_value (dst, tx_subdev_spec))
>     subdev = usrp.selected_subdev(dst, tx_subdev_spec)
>     r = dst.tune(subdev._which, subdev, options.tx_freq )
>     
>     filename = "/home/polytech/Desktop/usrp_data_receive.dat" 
>     destination = gr.file_sink(gr.sizeof_gr_complex, filename)
> 
>     self.connect(rx_src,  destination)
>     self.connect(rx_src, self.amp, dst)
> 
> if __name__ == '__main__':
>     try:
>         my_graph().run()
>     except KeyboardInterrupt:
>         pass