Hi all,
I have made up a simple PLL block in GRC using a multiplier phase detector, low
pass filter (FIR) and VCO to lock to a 1KHz reference. When I run the
simulation, it gives me a run time error "flow graph has loops!". Does it mean
that I cannot make any kind of feedback system in the gnuradio or is there
something else to ponder? Also, I am adding "1" to the output of the low pass
filter so that when the phase error (output of low pass filter) becomes zero in
the locked state, the VCO then runs at its quiescent frequency of 1KHz (I have
set the sensitivity of VCO as 2*pi*1K rad/s/V). Is it the right way to use VCO?
Below is the error message:
------------------------------------------------------
------------------------------------------------------
Generating: "/home/mahboob/Desktop/top_block.py"
Executing: "/home/mahboob/Desktop/top_block.py"
>>> gr_fir_fff: using SSE
Traceback (most recent call last):
File "/home/mahboob/Desktop/top_block.py", line 71, in <module>
tb.Run(True)
File "/usr/lib/python2.6/dist-packages/grc_gnuradio/wxgui/top_block_gui.py",
line 73, in Run
if start: self.start()
File "/usr/lib/python2.6/dist-packages/gnuradio/gr/top_block.py", line 97, in
start
self._tb.start()
File
"/usr/lib/python2.6/dist-packages/gnuradio/gr/gnuradio_swig_py_runtime.py",
line 1455, in start
return _gnuradio_swig_py_runtime.gr_top_block_sptr_start(self)
RuntimeError: flow graph has loops!
_______________________________________________
Discuss-gnuradio mailing list
Discuss-gnuradio@gnu.org
http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
