GNUradio python code for spread spectrum communication using USRP
Here is a sample GNUradio Python code for spread spectrum communication using USRP:
#!/usr/bin/env python
from gnuradio import gr, uhd
from gnuradio import analog
from gnuradio.filter import firdes
class my_top_block(gr.top_block):
def __init__(self):
gr.top_block.__init__(self)
# Set up the USRP source and sink
self.u = uhd.usrp_sink(device_addr="", stream_args=uhd.stream_args(cpu_format="fc32", channels=range(1),),)
self.u.set_samp_rate(1e6)
self.u.set_center_freq(915e6)
self.u.set_gain(10)
self.u.set_antenna("TX/RX")
self.u2 = uhd.usrp_source(device_addr="", stream_args=uhd.stream_args(cpu_format="fc32", channels=range(1),),)
self.u2.set_samp_rate(1e6)
self.u2.set_center_freq(915e6)
self.u2.set_gain(10)
self.u2.set_antenna("TX/RX")
# Generate a random bit stream to be transmitted
self.src = analog.random_source(gr.sizeof_char, 100)
# Convert the bit stream to a complex baseband signal using BPSK modulation
self.mod = analog.modulate_waveform(bpsk_data, 2*np.pi*np.linspace(0, 1, 100))
# Apply direct sequence spread spectrum to the signal
self.spread = np.tile(np.random.randint(0, 2, 100), 10)
self.spread[self.spread == 0] = -1
self.signal = np.multiply(self.mod, self.spread)
# Create a low-pass filter to smooth out the edges of the signal
self.lpfilter = firdes.low_pass(1, 1e6, 100e3, 10e3, firdes.WIN_HAMMING)
# Connect the signal to the USRP sink and source
self.sink = self.u
self.connect(self.src, self.signal, self.lpfilter, self.sink)
self.source = self.u2
self.connect(self.source, self.lpfilter)
if __name__ == '__main__':
try:
my_top_block().run()
except KeyboardInterrupt:
pass
This code generates a random bit stream, applies BPSK modulation to it, and then applies direct sequence spread spectrum using a random spreading code. The resulting spread spectrum signal is then low-pass filtered and transmitted using a USRP sink. The same signal is also received by a USRP source, low-pass filtered, and then processed. Note that this code is just an example and may need to be modified to suit your specific use case.