How to use several DDC in usrp?

Hello

I am using a usrp1 populated with 2 LFRX and 2 LFTX daughter boards.

I want to use the 2 ADC of LFRX-A to sample s different signals.

To do this I use set_subdev_spec(“A:A B:A”,0).

In order to avoid a segmentation fault I apparently have to create the
rx with num_channels=2.

But now I get the error-message:

RuntimeError: gr uhd usrp source(4): insufficient connected output ports
(2 needed, 1 connected)

My questions:

  1. Is the num_channels argument to uhd.usrp_source specifying the number
    of active DDCs?

  2. How do I connect more than 1 port to uhd.usrp_source? In pre-uhd this
    was achieved using gr.deinterleave - but this does not seem to work
    anymore.

Here is the code:

#!/usr/bin/python

from gnuradio import gr
from gnuradio import uhd
from gnuradio.eng_option import eng_option

class build_block(gr.top_block):
def init(self):
gr.top_block.init(self)

    self.u_tx = 

uhd.usrp_sink(“serial=47432785”,uhd.stream_args(‘fc32’))
self.siggen_tx =
gr.sig_source_c(self.u_tx.get_samp_rate(),gr.GR_CONST_WAVE,0, 1.0, 0)

self.head_tx = gr.head(gr.sizeof_gr_complex, 1000000)

    self.head_tx   = gr.head(gr.sizeof_gr_complex, 1000)
    self.u_tx.set_subdev_spec("A:AB",0)
    self.u_tx.set_center_freq(10e6)
    self.u_tx.set_samp_rate(1e6)
    self.u_tx.get_samp_rate()

self.u_rx =

uhd.usrp_source(“serial=47432785”,uhd.stream_args(‘fc32’),num_channels=1)
self.u_rx =
uhd.usrp_source(“serial=47432785”,io_type=uhd.io_type.COMPLEX_FLOAT32,num_channels=2)

self.u_rx.set_subdev_spec(“A:A B:A”,0)

    self.u_rx.set_subdev_spec("A:A B:A",0)
    self.u_rx.set_center_freq(10e6+1e3)
    self.u_rx.set_samp_rate(250e3)
    self.head_rx_0 = gr.head(gr.sizeof_gr_complex, 1000)
    self.dst0 = gr.file_sink(gr.sizeof_gr_complex, "r.dat")

self.di = gr.deinterleave(gr.sizeof_gr_complex)

self.connect (self.siggen_tx,self.head_tx, self.u_tx)

    self.connect (self.u_rx,self.head_rx_0,self.dst0)

self.connect (self.u_rx,self.di)

tb = build_block ()
tb.run ()

Thanks

Wolfgang

On 05/26/2013 01:10 PM, Wolfgang Buesser wrote:

But now I get the error-message:

RuntimeError: gr uhd usrp source(4): insufficient connected output ports (2
needed, 1 connected)

My questions:

  1. Is the num_channels argument to uhd.usrp_source specifying the number of
    active DDCs?

  2. How do I connect more than 1 port to uhd.usrp_source? In pre-uhd this was
    achieved using gr.deinterleave - but this does not seem to work anymore.

The block has 2 output ports in this case.

-josh


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