Hello,
I've been trying to create a program to estimate the Bit Error Rate of some
modulations, but found some bugs on it.
After trying to exactly where the bug was, I could set it apart from the
rest of the code, here is a simple program where the bugs appear:
*CODE*
from gnuradio import gr, blks2
import time
class graph(gr.top_block):
def __init__(self):
gr.top_block.__init__(self)
self.src = gr.glfsr_source_b(20, True, 0, 42) #bit generator
self.mod = blks2.dbpsk_mod(5)
self.demod = blks2.dbpsk_demod(5)
self.xor = gr.xor_bb()
self.probe = gr.probe_density_b(0.01) #1's density in xored input
and output is ber
self.connect(self.src,self.mod,self.demod,(self.xor,0))
self.connect(self.src,(self.xor,1))
self.connect(self.xor,self.probe)
def ber(self):
return self.probe.density()
if __name__ == '__main__':
try:
tb = graph()
tb.start()
while True:
print tb.ber()
time.sleep(0.2)
tb.wait()
except KeyboardInterrupt:
pass
*END OF CODE*
The three problems I've got are:
1- The demodulator outputs more bits than it was sent, if we put a
gr.head(100) in the source, the demod generates more than 100 bits.
2- src bit sequence and the demodulated bit sequence are very different,
even after the lock of the demod. That's strange because there's no noise in
this channel.
3- Some seconds after the execution of the code, the probe density stops
changing, like if the program was not running anymore.
Thanks for helping,
Dinart
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