Hi,
I am trying to build a simple FM transmitter. The signal should be send
by
the USRP to an Spectrum Analyzer. I connected the Daughterboard BasicTX
(TX_A) to a Spectrum Analyzer, but I didn’t see the expected Spectrum.
I used the Frequency Mod Block in grc. I think this Block should
modulate
the signal and the USRP send it out on 12,8 MHz. I hope you can help me
building a graph who do this simple task of frequency modulation. I also
tried the example on this website
http://www.opendigitalradio.org/index.php/Simple_FM_transmitter_using_gnuradio
, but on the spectrum analyzer i also didn’t see the expected values.
from gnuradio import gr
from gnuradio.eng_option import eng_option
from grc_gnuradio import usrp as grc_usrp
from grc_gnuradio import wxgui as grc_wxgui
from optparse import OptionParser
import wx
class top_block(grc_wxgui.top_block_gui):
def init(self):
grc_wxgui.top_block_gui.init(self, title=“Top Block”)
##################################################
# Variables
##################################################
self.samp_rate = samp_rate = 32000
##################################################
# Blocks
##################################################
self.gr_frequency_modulator_fc_0 = gr.frequency_modulator_fc(3)
self.gr_multiply_const_vxx_0 = gr.multiply_const_vcc((100, ))
self.gr_multiply_const_vxx_1 = gr.multiply_const_vff((10, ))
self.gr_sig_source_x_0_0 = gr.sig_source_f(6400, gr.GR_CONST_WAVE,
3200,
1, 0)
self.usrp_simple_sink_x_0 = grc_usrp.simple_sink_c(which=0,
side=“A”)
self.usrp_simple_sink_x_0.set_interp_rate(200)
self.usrp_simple_sink_x_0.set_frequency(12800000, verbose=True)
self.usrp_simple_sink_x_0.set_gain(0)
##################################################
# Connections
##################################################
self.connect((self.gr_frequency_modulator_fc_0, 0),
(self.gr_multiply_const_vxx_0, 0))
self.connect((self.gr_sig_source_x_0_0, 0),
(self.gr_multiply_const_vxx_1,
0))
self.connect((self.gr_multiply_const_vxx_1, 0),
(self.gr_frequency_modulator_fc_0, 0))
self.connect((self.gr_multiply_const_vxx_0, 0),
(self.usrp_simple_sink_x_0, 0))
def set_samp_rate(self, samp_rate):
self.samp_rate = samp_rate
if name == ‘main’:
parser = OptionParser(option_class=eng_option, usage="%prog:
[options]")
(options, args) = parser.parse_args()
tb = top_block()
tb.Run(True)
–
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You helped me a lot