diff --git a/python/cqpsk-demod.py b/python/cqpsk-demod.py
new file mode 100755
index 0000000..19b9357
--- /dev/null
+++ b/python/cqpsk-demod.py
@@ -0,0 +1,89 @@
+#!/usr/bin/env python
+#
+# Copyright 2005,2006,2007 Free Software Foundation, Inc.
+#
+# cqpsk.py (C) Copyright 2009, KA1RBI
+# 
+# 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.
+#
+
+import sys
+import math
+from gnuradio import gr, gru, audio, eng_notation, blks2, optfir, fsk4
+from gnuradio.eng_option import eng_option
+from optparse import OptionParser
+
+# accepts an input file in complex format 
+# applies frequency translation, resampling (interpolation/decimation)
+# resampled result is CQPSK demodulated then decoded via fsk4.apco25_f()
+
+class my_top_block(gr.top_block):
+    def __init__(self):
+        gr.top_block.__init__(self)
+        parser = OptionParser(option_class=eng_option)
+
+        parser.add_option("-c", "--calibration", type="int", default=0, help="freq offset")
+        parser.add_option("-i", "--input-file", type="string", default="in.dat", help="specify the input file")
+        parser.add_option("-l", "--log", action="store_true", default=False, help="dump debug .dat files")
+        parser.add_option("-L", "--low-pass", type="eng_float", default=15e3, help="low pass cut-off", metavar="Hz")
+        parser.add_option("-o", "--output-file", type="string", default="out.dat", help="specify the output file")
+        parser.add_option("-s", "--sample-rate", type="int", default=250000, help="input sample rate")
+        parser.add_option("-v", "--verbose", action="store_true", default=False, help="dump demodulation data")
+        (options, args) = parser.parse_args()
+ 
+        sample_rate = options.sample_rate
+        symbol_rate = 4800
+        sps = 10
+        # output rate will be 48,000
+        ntaps = 11 * sps
+        new_sample_rate = symbol_rate * sps
+        lcm = gru.lcm(sample_rate, new_sample_rate)
+        interp = lcm // sample_rate
+        decim  = lcm // new_sample_rate
+
+        channel_taps = gr.firdes.low_pass(1.0, sample_rate, options.low_pass, options.low_pass * 0.1, gr.firdes.WIN_HANN)
+
+        FILTER = gr.freq_xlating_fir_filter_ccf(1, channel_taps, options.calibration, sample_rate)
+
+        sys.stderr.write("interp: %d decim: %d\n" %(interp, decim))
+
+        bpf_taps = gr.firdes.low_pass(1.0, sample_rate * interp, options.low_pass, options.low_pass * 0.1, gr.firdes.WIN_HANN)
+        INTERPOLATOR = gr.interp_fir_filter_ccf (int(interp), bpf_taps)
+        DECIMATOR = blks2.rational_resampler_ccf(1, int(decim))
+
+        IN = gr.file_source(gr.sizeof_gr_complex, options.input_file)
+
+        DEMOD = blks2.cqpsk_demod( samples_per_symbol = sps,
+                                 excess_bw=0.35,
+                                 costas_alpha=0.03,
+                                 gain_mu=0.05,
+                                 mu=0.05,
+                                 omega_relative_limit=0.05,
+                                 log=options.log,
+                                 verbose=options.verbose)
+
+        msgq = gr.msg_queue()
+        DECODER = fsk4.apco25_f(msgq,0)
+
+        self.connect(IN, FILTER, INTERPOLATOR, DECIMATOR, DEMOD, DECODER)
+
+if __name__ == "__main__":
+    try:
+        my_top_block().run()
+    except KeyboardInterrupt:
+        tb.stop()
diff --git a/python/cqpsk-mod.py b/python/cqpsk-mod.py
new file mode 100755
index 0000000..b82ce63
--- /dev/null
+++ b/python/cqpsk-mod.py
@@ -0,0 +1,65 @@
+#!/usr/bin/env python
+#
+# Copyright 2005,2006,2007 Free Software Foundation, Inc.
+#
+# cqpsk.py (C) Copyright 2009, KA1RBI
+# 
+# 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.
+#
+
+import math
+from gnuradio import gr, gru, audio, eng_notation, blks2, optfir
+from gnuradio.eng_option import eng_option
+from optparse import OptionParser
+
+# produces an output file in complex format at sampling rate=48000
+# the input file (a character stream) is used to produce the modulated
+# complex output file.
+
+class my_top_block(gr.top_block):
+    def __init__(self):
+        gr.top_block.__init__(self)
+        parser = OptionParser(option_class=eng_option)
+
+        parser.add_option("-i", "--input-file", type="string", default="in.dat", help="specify the input file")
+        parser.add_option("-l", "--log", action="store_true", default=False, help="dump debug .dat files")
+        parser.add_option("-o", "--output-file", type="string", default="out.dat", help="specify the output file")
+        parser.add_option("-s", "--sample-rate", type="int", default=48000, help="input sample rate")
+        parser.add_option("-v", "--verbose", action="store_true", default=False, help="dump demodulation data")
+        (options, args) = parser.parse_args()
+ 
+        IN = gr.file_source(gr.sizeof_char, options.input_file)
+
+        symbol_rate = 4800
+	sample_rate = options.sample_rate
+        sps = sample_rate // symbol_rate
+
+        ENC = blks2.cqpsk_mod(samples_per_symbol=sps,
+                                 log=options.log,
+                                 verbose=options.verbose)
+
+        OUT = gr.file_sink(gr.sizeof_gr_complex, options.output_file)
+
+        self.connect(IN, ENC, OUT)
+
+if __name__ == "__main__":
+    try:
+        my_top_block().run()
+    except KeyboardInterrupt:
+        tb.stop()
+
diff --git a/python/cqpsk.py b/python/cqpsk.py
new file mode 100644
index 0000000..e8362fb
--- /dev/null
+++ b/python/cqpsk.py
@@ -0,0 +1,350 @@
+#
+# Copyright 2005,2006,2007 Free Software Foundation, Inc.
+#
+# cqpsk.py (C) Copyright 2009, KA1RBI
+# 
+# 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.
+# 
+
+# See gnuradio-examples/python/digital for examples
+
+"""
+differential PI/4 CQPSK modulation and demodulation.
+"""
+
+from gnuradio import gr, gru, modulation_utils
+from math import pi, sqrt
+import psk
+import cmath
+from pprint import pprint
+
+# default values (used in __init__ and add_options)
+_def_samples_per_symbol = 10
+_def_excess_bw = 0.35
+_def_gray_code = True
+_def_verbose = False
+_def_log = False
+
+_def_costas_alpha = 0.15
+_def_gain_mu = None
+_def_mu = 0.5
+_def_omega_relative_limit = 0.005
+
+
+# /////////////////////////////////////////////////////////////////////////////
+#                           CQPSK modulator
+# /////////////////////////////////////////////////////////////////////////////
+
+class cqpsk_mod(gr.hier_block2):
+
+    def __init__(self,
+                 samples_per_symbol=_def_samples_per_symbol,
+                 excess_bw=_def_excess_bw,
+                 verbose=_def_verbose,
+                 log=_def_log):
+        """
+	Hierarchical block for RRC-filtered QPSK modulation.
+
+	The input is a byte stream (unsigned char) and the
+	output is the complex modulated signal at baseband.
+
+	@param samples_per_symbol: samples per symbol >= 2
+	@type samples_per_symbol: integer
+	@param excess_bw: Root-raised cosine filter excess bandwidth
+	@type excess_bw: float
+        @param verbose: Print information about modulator?
+        @type verbose: bool
+        @param debug: Print modualtion data to files?
+        @type debug: bool
+	"""
+
+	gr.hier_block2.__init__(self, "cqpsk_mod",
+				gr.io_signature(1, 1, gr.sizeof_char),       # Input signature
+				gr.io_signature(1, 1, gr.sizeof_gr_complex)) # Output signature
+
+        self._samples_per_symbol = samples_per_symbol
+        self._excess_bw = excess_bw
+
+        if not isinstance(samples_per_symbol, int) or samples_per_symbol < 2:
+            raise TypeError, ("sbp must be an integer >= 2, is %d" % samples_per_symbol)
+
+	ntaps = 11 * samples_per_symbol
+ 
+        arity = 8
+
+        # turn bytes into k-bit vectors
+        self.bytes2chunks = \
+          gr.packed_to_unpacked_bb(self.bits_per_symbol(), gr.GR_MSB_FIRST)
+
+        #	0	+45	1	[+1]
+        #	1	+135	3	[+3]
+        #	2	-45	7	[-1]
+        #	3	-135	5	[-3]
+        self.pi4map = [1, 3, 7, 5]
+        self.symbol_mapper = gr.map_bb(self.pi4map)
+        self.diffenc = gr.diff_encoder_bb(arity)
+        self.chunks2symbols = gr.chunks_to_symbols_bc(psk.constellation[arity])
+
+        # pulse shaping filter
+	self.rrc_taps = gr.firdes.root_raised_cosine(
+	    self._samples_per_symbol, # gain  (sps since we're interpolating by sps)
+            self._samples_per_symbol, # sampling rate
+            1.0,		      # symbol rate
+            self._excess_bw,          # excess bandwidth (roll-off factor)
+            ntaps)
+
+	self.rrc_filter = gr.interp_fir_filter_ccf(self._samples_per_symbol, self.rrc_taps)
+
+        if verbose:
+            self._print_verbage()
+        
+        if log:
+            self._setup_logging()
+            
+	# Connect & Initialize base class
+        self.connect(self, self.bytes2chunks, self.symbol_mapper, self.diffenc,
+                     self.chunks2symbols, self.rrc_filter, self)
+
+    def samples_per_symbol(self):
+        return self._samples_per_symbol
+
+    def bits_per_symbol(self=None):   # staticmethod that's also callable on an instance
+        return 2
+    bits_per_symbol = staticmethod(bits_per_symbol)      # make it a static method.  RTFM
+
+    def _print_verbage(self):
+        print "\nModulator:"
+        print "bits per symbol:     %d" % self.bits_per_symbol()
+        print "Gray code:           %s" % self._gray_code
+        print "RRS roll-off factor: %f" % self._excess_bw
+
+    def _setup_logging(self):
+        print "Modulation logging turned on."
+        self.connect(self.bytes2chunks,
+                     gr.file_sink(gr.sizeof_char, "tx_bytes2chunks.dat"))
+        self.connect(self.symbol_mapper,
+                     gr.file_sink(gr.sizeof_char, "tx_graycoder.dat"))
+        self.connect(self.diffenc,
+                     gr.file_sink(gr.sizeof_char, "tx_diffenc.dat"))        
+        self.connect(self.chunks2symbols,
+                     gr.file_sink(gr.sizeof_gr_complex, "tx_chunks2symbols.dat"))
+        self.connect(self.rrc_filter,
+                     gr.file_sink(gr.sizeof_gr_complex, "tx_rrc_filter.dat"))
+
+    def add_options(parser):
+        """
+        Adds QPSK modulation-specific options to the standard parser
+        """
+        parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
+                          help="set RRC excess bandwith factor [default=%default] (PSK)")
+        parser.add_option("", "--no-gray-code", dest="gray_code",
+                          action="store_false", default=_def_gray_code,
+                          help="disable gray coding on modulated bits (PSK)")
+    add_options=staticmethod(add_options)
+
+
+    def extract_kwargs_from_options(options):
+        """
+        Given command line options, create dictionary suitable for passing to __init__
+        """
+        return modulation_utils.extract_kwargs_from_options(dqpsk_mod.__init__,
+                                                            ('self',), options)
+    extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
+
+
+# /////////////////////////////////////////////////////////////////////////////
+#                           CQPSK demodulator
+#
+# /////////////////////////////////////////////////////////////////////////////
+
+class cqpsk_demod(gr.hier_block2):
+
+    def __init__(self, 
+                 samples_per_symbol=_def_samples_per_symbol,
+                 excess_bw=_def_excess_bw,
+                 costas_alpha=_def_costas_alpha,
+                 gain_mu=_def_gain_mu,
+                 mu=_def_mu,
+                 omega_relative_limit=_def_omega_relative_limit,
+                 gray_code=_def_gray_code,
+                 verbose=_def_verbose,
+                 log=_def_log):
+        """
+	Hierarchical block for RRC-filtered CQPSK demodulation
+
+	The input is the complex modulated signal at baseband.
+	The output is a stream of floats in [ -3 / -1 / +1 / +3 ]
+
+	@param samples_per_symbol: samples per symbol >= 2
+	@type samples_per_symbol: float
+	@param excess_bw: Root-raised cosine filter excess bandwidth
+	@type excess_bw: float
+        @param costas_alpha: loop filter gain
+        @type costas_alphas: float
+        @param gain_mu: for M&M block
+        @type gain_mu: float
+        @param mu: for M&M block
+        @type mu: float
+        @param omega_relative_limit: for M&M block
+        @type omega_relative_limit: float
+        @param gray_code: Tell modulator to Gray code the bits
+        @type gray_code: bool
+        @param verbose: Print information about modulator?
+        @type verbose: bool
+        @param debug: Print modualtion data to files?
+        @type debug: bool
+	"""
+
+	gr.hier_block2.__init__(self, "cqpsk_demod",
+			        gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
+			        gr.io_signature(1, 1, gr.sizeof_float))       # Output signature
+
+        self._samples_per_symbol = samples_per_symbol
+        self._excess_bw = excess_bw
+        self._costas_alpha = costas_alpha
+        self._mm_gain_mu = gain_mu
+        self._mm_mu = mu
+        self._mm_omega_relative_limit = omega_relative_limit
+        self._gray_code = gray_code
+
+        if samples_per_symbol < 2:
+            raise TypeError, "sbp must be >= 2, is %d" % samples_per_symbol
+
+        arity = pow(2,self.bits_per_symbol())
+ 
+        # Automatic gain control
+        scale = (1.0/16384.0)
+        self.pre_scaler = gr.multiply_const_cc(scale)   # scale the signal from full-range to +-1
+        #self.agc = gr.agc2_cc(0.6e-1, 1e-3, 1, 1, 100)
+        self.agc = gr.feedforward_agc_cc(16, 2.0)
+       
+        # RRC data filter
+        ntaps = 11 * samples_per_symbol
+        self.rrc_taps = gr.firdes.root_raised_cosine(
+            1.0,                      # gain
+            self._samples_per_symbol, # sampling rate
+            1.0,                      # symbol rate
+            self._excess_bw,          # excess bandwidth (roll-off factor)
+            ntaps)
+        self.rrc_filter=gr.interp_fir_filter_ccf(1, self.rrc_taps)        
+
+        if not self._mm_gain_mu:
+            sbs_to_mm = {2: 0.050, 3: 0.075, 4: 0.11, 5: 0.125, 6: 0.15, 7: 0.15}
+            self._mm_gain_mu = sbs_to_mm[samples_per_symbol]
+
+        self._mm_omega = self._samples_per_symbol
+        self._mm_gain_omega = .25 * self._mm_gain_mu * self._mm_gain_mu
+        self._costas_beta  = 0.25 * self._costas_alpha * self._costas_alpha
+        fmin = -0.025
+        fmax = 0.025
+        
+        self.receiver=gr.mpsk_receiver_cc(arity, pi/4.0,
+                                          self._costas_alpha, self._costas_beta,
+                                          fmin, fmax,
+                                          self._mm_mu, self._mm_gain_mu,
+                                          self._mm_omega, self._mm_gain_omega,
+                                          self._mm_omega_relative_limit)
+
+        # Perform Differential decoding on the constellation
+        self.diffdec = gr.diff_phasor_cc()
+
+        # take angle of the difference (in radians)
+        self.to_float = gr.complex_to_arg()
+
+        # convert from radians such that signal is in -3/-1/+1/+3
+        self.rescale = gr.multiply_const_ff( 1 / (pi / 4) )
+
+        if verbose:
+            self._print_verbage()
+        
+        if log:
+            self._setup_logging()
+ 
+        # Connect & Initialize base class
+        self.connect(self, self.pre_scaler, self.agc, self.rrc_filter, self.receiver,
+                     self.diffdec, self.to_float, self.rescale, self)
+
+    def samples_per_symbol(self):
+        return self._samples_per_symbol
+
+    def bits_per_symbol(self=None):   # staticmethod that's also callable on an instance
+        return 2
+    bits_per_symbol = staticmethod(bits_per_symbol)      # make it a static method.  RTFM
+
+    def _print_verbage(self):
+        print "\nDemodulator:"
+        print "bits per symbol:     %d"   % self.bits_per_symbol()
+        print "Gray code:           %s"   % self._gray_code
+        print "RRC roll-off factor: %.2f" % self._excess_bw
+        print "Costas Loop alpha:   %.2e" % self._costas_alpha
+        print "Costas Loop beta:    %.2e" % self._costas_beta
+        print "M&M mu:              %.2f" % self._mm_mu
+        print "M&M mu gain:         %.2e" % self._mm_gain_mu
+        print "M&M omega:           %.2f" % self._mm_omega
+        print "M&M omega gain:      %.2e" % self._mm_gain_omega
+        print "M&M omega limit:     %.2f" % self._mm_omega_relative_limit
+
+    def _setup_logging(self):
+        print "Modulation logging turned on."
+        self.connect(self.pre_scaler,
+                     gr.file_sink(gr.sizeof_gr_complex, "rx_prescaler.dat"))
+        self.connect(self.agc,
+                     gr.file_sink(gr.sizeof_gr_complex, "rx_agc.dat"))
+        self.connect(self.rrc_filter,
+                     gr.file_sink(gr.sizeof_gr_complex, "rx_rrc_filter.dat"))
+        self.connect(self.receiver,
+                     gr.file_sink(gr.sizeof_gr_complex, "rx_receiver.dat"))
+        self.connect(self.diffdec,
+                     gr.file_sink(gr.sizeof_gr_complex, "rx_diffdec.dat"))        
+        self.connect(self.to_float,
+                     gr.file_sink(gr.sizeof_float, "rx_to_float.dat"))
+        self.connect(self.rescale,
+                     gr.file_sink(gr.sizeof_float, "rx_rescale.dat"))
+
+    def add_options(parser):
+        """
+        Adds modulation-specific options to the standard parser
+        """
+        parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
+                          help="set RRC excess bandwith factor [default=%default] (PSK)")
+        parser.add_option("", "--no-gray-code", dest="gray_code",
+                          action="store_false", default=_def_gray_code,
+                          help="disable gray coding on modulated bits (PSK)")
+        parser.add_option("", "--costas-alpha", type="float", default=_def_costas_alpha,
+                          help="set Costas loop alpha value [default=%default] (PSK)")
+        parser.add_option("", "--gain-mu", type="float", default=_def_gain_mu,
+                          help="set M&M symbol sync loop gain mu value [default=%default] (PSK)")
+        parser.add_option("", "--mu", type="float", default=_def_mu,
+                          help="set M&M symbol sync loop mu value [default=%default] (PSK)")
+    add_options=staticmethod(add_options)
+
+    def extract_kwargs_from_options(options):
+        """
+        Given command line options, create dictionary suitable for passing to __init__
+        """
+        return modulation_utils.extract_kwargs_from_options(
+            cqpsk_demod.__init__, ('self',), options)
+    extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
+
+
+#
+# Add these to the mod/demod registry
+#
+modulation_utils.add_type_1_mod('cqpsk', cqpsk_mod)
+modulation_utils.add_type_1_demod('cqpsk', cqpsk_demod)
+