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# Copyright 2011 Free Software Foundation, Inc.
#
# This file is part of GNU Radio
#
# GNU Radio is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3, or (at your option)
# any later version.
#
# GNU Radio is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with GNU Radio; see the file COPYING. If not, write to
# the Free Software Foundation, Inc., 51 Franklin Street,
# Boston, MA 02110-1301, USA.
# post detection agc processing
#
# This agc strategy is copied more or less verbatim from
# weaver_isb_am1_usrp3.py by cswiger.
#
# Thanks.
#
# Then modified in a variety of ways.
#
# There doesn't appear to be a way to hook multiple blocks to the
# input port when building a hier block like this. Thus the
# split below.
#
# Basic operation.
# Power is estimated by squaring the input.
# Low pass filter using a 1 pole iir.
# The time constant can be tweaked by changing the taps.
# Currently there is no implementation to change this while operating
# a potentially useful addition.
# The log block turns this into dB
# gain adjusts the agc authority.
#
# M. Revnell 2006-Jan
from gnuradio import gr
class agc( gr.hier_block2 ):
def __init__( self ):
gr.hier_block2.__init__(self, "agc",
gr.io_signature(1,1,gr.sizeof_float),
gr.io_signature(1,1,gr.sizeof_float))
self.split = gr.multiply_const_ff( 1 )
self.sqr = gr.multiply_ff( )
self.int0 = gr.iir_filter_ffd( [.004, 0], [0, .999] )
self.offs = gr.add_const_ff( -30 )
self.gain = gr.multiply_const_ff( 70 )
self.log = gr.nlog10_ff( 10, 1 )
self.agc = gr.divide_ff( )
self.connect(self, self.split)
self.connect(self.split, (self.agc, 0))
self.connect(self.split, (self.sqr, 0))
self.connect(self.split, (self.sqr, 1))
self.connect(self.sqr, self.int0)
self.connect(self.int0, self.log)
self.connect(self.log, self.offs)
self.connect(self.offs, self.gain)
self.connect(self.gain, (self.agc, 1))
self.connect(self.agc, self)
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