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[Discuss-gnuradio] QPSK Demodulator
From: |
Pepito31 Pepito31 |
Subject: |
[Discuss-gnuradio] QPSK Demodulator |
Date: |
Tue, 1 Jul 2008 20:18:21 +0200 |
Hi all,
I'm working on a qpsk demodulator (not differential), see code below :
# Connect & Initialize base class
self.connect(self,self.pre_scaler, self.agc, self.costas_loop,
self.rrc_filter, self.clock_recovery)
self.connect(self.clock_recovery, self.diffdec, self.slicer,
self.symbol_mapper,self.unpack, self)
I've removed the diff_phasor block in the flowgraph. By default the
constellation mapper use :
# find closest constellation point
rot = 1
#rot = .707 + .707j
rotated_const = map(lambda pt: pt * rot,
psk.constellation[arity])
#print "rotated_const = %s" % rotated_const
self.slicer = gr.constellation_decoder_cb(rotated_const,
range(arity))
if self._gray_code:
self.symbol_mapper = gr.map_bb(psk.gray_to_binary[arity])
else:
self.symbol_mapper = gr.map_bb(psk.ungray_to_binary[arity])
I would like to know if rot has to be set to 1 or 0.707 + 0.707j as I
have removed the diff_phasor ?
When I draw the constellation after the clock_recovery block, I see
graphicaly that the symbol are located around +45°, 135°,225°,-45°.
Best regards,
Pepito
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- [Discuss-gnuradio] QPSK Demodulator,
Pepito31 Pepito31 <=