Sending pre-saved OFDM file to USRP

Hi,

I’m trying to send a pre-saved OFDM file to a transmitter USRP, and to
receive the signal from a receiver USRP.
From the ‘benchmark_ofdm_tx.py’ I’ve saved the OFDM signal to a file
using ‘gr.file_sink’, instead of sending it to ‘usrp.sink_c’.
And then I want to read the data from the saved file and send it though
the transmitter USRP, and receive it from the other USRP, but does not
work.

Could anyone give tip, why it does not work? Or give help how to make it
work?

This is my code:

#!/usr/bin/env python

from gnuradio import gr
from gnuradio import usrp

from numpy import *

class send_from_file_graph (gr.flow_graph):

def __init__(self):
gr.flow_graph.__init__(self)

filename = 'tx_usrp_data.dat'
# which I had saved from 'benchmark_ofdm_tx.py' using 

‘gr.file_sink(gr.sizeof_gr_complex, filename)’
src = gr.file_source ( gr.sizeof_gr_complex, filename, False)

self.v_snk = gr.vector_sink_c()

# setup usrp
self.u = usrp.sink_c(fusb_block_size=0, fusb_nblocks=0)
self.u.set_interp_rate(512)
self._tx_subdev_spec = usrp.pick_tx_subdevice(self.u)
self.subdev = usrp.selected_subdev(self.u, self._tx_subdev_spec)

self.u.tune(self.subdev._which, self.subdev, 2.45e9)
self.subdev.set_gain(200)
self.subdev.set_auto_tr(True)
# ##

self.connect(src, self.v_snk)
self.run()
v_src = gr.vector_source_c(self.v_snk.data())
self.connect(v_src, self.u)
self.run()

def main():

fg = send_from_file_graph ()
fg.start()

if name==‘main’:
try:
main()
except KeyboardInterrupt:
pass

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Hoo-chang Shin wrote:

gr.flow_graph.__init__(self)
self._tx_subdev_spec = usrp.pick_tx_subdevice(self.u)
self.connect(v_src, self.u)
self.run()

Why don’t you just do:

self.connect(src, self.u)

Instead of all the vector stuff in the middle?

Tom

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