Problems with 2 RX

GNU Radio
1

Hi everyone!
We’re trying to receive two signals from two different RFX2400 in the
same USRP. We’ve already read everything about setting the rx mux and
the n_channels. However, we still cannot receive the two signals
correctly.
When we put signal in the first Rx1 (that goes to one RFX2400), we can
see it, but we cannot see the other in Rx2 (to the other RFX2400),
it’s like it hasn’t any kind of input signal. I add the code. We don’t
know if it’s a problem of the deinterleave, or the mux. Thanks in
advance

class my_graph(stdgui.gui_flow_graph):

def __init__(self,frame,panel,vbox,argv):

stdgui.gui_flow_graph.init (self,frame,panel,vbox,argv)

sample_rate = 320000
freq = 2450000000
usrp_decim = 200
decim = 10
#USRP
src = usrp.source_c(0, usrp_decim, fpga_filename=“std_2rxhb_2tx.rbf”)
src.set_mux(gru.hexint(0x32103210))
src.set_nchannels(2)
subdev_spec1 = (0,0)
subdev_spec2 = (1,0)
subdev1 = usrp.selected_subdev(src, subdev_spec1)
subdev2 = usrp.selected_subdev(src, subdev_spec2)
subdev1.set_auto_tr(True)
subdev2.set_auto_tr(True)
subdev1.select_rx_antenna(‘RX2’)
subdev2.select_rx_antenna(‘RX2’)
r=src.tune(0,subdev1,freq)
r=src.tune(0,subdev2,freq)
self.fft_1=fftsink.fft_sink_c(self,panel,0,10,50,sample_rate,512,2)
self.fft_2=fftsink.fft_sink_c(self,panel,0,10,50,sample_rate,512,2)
di=gr.deinterleave(gr.sizeof_gr_complex)
fg = gr.flow_graph ()

self.connect (src,di)
self.connect ((di,0),self.fft_1)
self.connect ((di,1),self.fft_2)
self._build_gui(vbox)

def _build_gui(self, vbox):

vbox.Add(self.fft_1.win, 10, wx.EXPAND)
vbox.Add(self.fft_2.win, 10, wx.EXPAND)

if name == ‘main’:
app = stdgui.stdapp (my_graph, " ")
app.MainLoop ()

2

On Wed, May 09, 2007 at 01:02:52PM +0200, Albert Rodriguez wrote:

src = usrp.source_c(0, usrp_decim, fpga_filename=“std_2rxhb_2tx.rbf”)
src.set_mux(gru.hexint(0x32103210))
src.set_nchannels(2)
subdev_spec1 = (0,0)
subdev_spec2 = (1,0)
subdev1 = usrp.selected_subdev(src, subdev_spec1)
subdev2 = usrp.selected_subdev(src, subdev_spec2)
subdev1.set_auto_tr(True)
subdev2.set_auto_tr(True)
subdev1.select_rx_antenna(‘RX2’)
subdev2.select_rx_antenna(‘RX2’)

These lines:

r=src.tune(0,subdev1,freq)
r=src.tune(0,subdev2,freq)

Should be:

r=src.tune(0,subdev1,freq)
r=src.tune(1,subdev2,freq)

BTW, checking the return value is always a good idea :wink:

3

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Eric B. wrote:

On Wed, May 09, 2007 at 01:02:52PM +0200, Albert Rodriguez wrote:

We’re trying to receive two signals from two different RFX2400 in the
same USRP. We’ve already read everything about setting the rx mux and

BTW, checking the return value is always a good idea :wink:
Can you explain this? I was under the impression that the first
parameter to tune was which USRP board, and they’re using the same USRP.

  • -Dan
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4

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Dan H. wrote:

r=src.tune(0,subdev1,freq)
r=src.tune(1,subdev2,freq)
BTW, checking the return value is always a good idea :wink:

Can you explain this? I was under the impression that the first
parameter to tune was which USRP board, and they’re using the same USRP.

No, no, I’m an idiot. That’s handled in usrp_source_c(…). Sorry.

  • -Dan
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5

On Wed, May 09, 2007 at 09:27:11AM -0700, Dan H. wrote:

Should be:

r=src.tune(0,subdev1,freq)
r=src.tune(1,subdev2,freq)

BTW, checking the return value is always a good idea :wink:

Can you explain this? I was under the impression that the first
parameter to tune was which USRP board, and they’re using the same USRP.

The first parameter to the CONSTRUCTOR is the USRP board.
In the call to tune, the first parameter is the channel that we want
to tune (in the code below from usrp.py, u is effectively self. Ignore
it.)

def tune(u, chan, subdev, target_freq):
“”"
Set the center frequency we’re interested in.

@param u: instance of usrp.source_* or usrp.sink_*
@param chan: DDC/DUC channel
@type  chan: int
@param subdev: daughterboard subdevice
@param target_freq: frequency in Hz
@returns False if failure else tune_result

Tuning is a two step process.  First we ask the front-end to
tune as close to the desired frequency as it can.  Then we use
the result of that operation and our target_frequency to
determine the value for the digital down converter.
"""