[Discuss-gnuradio] how to take input from multiple subdevices in the USRP simultaneously

[sHabzbd]

Hi Everyone:

I am guessing that my last post was not clear since I didnt get any replies.
So here I go again.

1. I am using two Flex900 daughter cards on a single USRP.
2. I am getting to select two subdevices (0,0) and (1,0) ie. daughter board
A or daughter board B
3. On each subdevice I am getting to select two antennas 'TX/RX' and 'RX2'

Now here is the thing. I can take anyone of the input at a single time, ie.
I can either get
a. subdevice(0,0) & antenna 'TX/RX'
b. subdevice(0,0) & antenna 'RX2'
c. subdevice(1,0) & antenna 'TX/RX'
d. subdevice(1,0) & antenna 'RX2'

That is I am getting to set the usrp mux with 
        tb.src_usrp.set_mux(usrp.determine_rx_mux_value(tb.src_usrp, subdevice))
and then select and antenna for the subdevice
        tb.subdev.select_rx_antenna('RX2')

But I need to build a graph where I can take at least two of the above
mentioned inputs. And store them in two separate sinks if possible. Using
two different sink_files.

Would really really appreciate any help or some direction or hint.

Thank you loads in advance.

Here goes the code that I could do so far.

##################################################################
#bring in blocks from the main gnu radio package
from gnuradio import gr

#bring in the USRP source/sink
from gnuradio import usrp
import sys
from gnuradio import audio

def build_graph():
 
        #create the top block 
        tb=gr.top_block()

        #creat the USRP source
        tb.src_usrp=usrp.source_c(decim_rate=16)

        #create a signal sink
        tb.sink_file = gr.file_sink(gr.sizeof_gr_complex, 'test89.dat')

        #create counter
        tb.count=gr.head(gr.sizeof_gr_complex, int(2000))

        #connect the source to the sink
        tb.connect(tb.src_usrp,tb.count,tb.sink_file)
        
        #choose the sub device
        #subdev_spec = usrp.pick_rx_subdevice(tb.src_usrp)
        subdev_spec = (0,0)
        #subdev_spec = (1,0)    

        #Set the mux
        tb.src_usrp.set_mux(usrp.determine_rx_mux_value(tb.src_usrp, 
subdev_spec))

        #get the sub-device
        tb.subdev = usrp.selected_subdev(tb.src_usrp, subdev_spec)

        #select receive antenna ('TX/RX' or 'RX2')
        #tb.subdev.select_rx_antenna('TX/RX')
        tb.subdev.select_rx_antenna('RX2')

        #Set the gain
        g=tb.subdev.gain_range()
        gain=float(g[0]+g[1])/2
        #gain=
        tb.subdev.set_gain(gain)

        #tune the center frequency
        frequency=float(948e6)
        tb.src_usrp.tune(0, tb.subdev, frequency)

        return tb

if __name__ == '__main__':
        tb = build_graph ()
        tb.start ()       
#################################################################

Thank you loads again.

Kind regards,

Shabbir Ahmed
PhD. Student
Victoria University, Melbourne, AUS


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