gr-digital: replace clk recovery MM in hier blks

As Clock Recovery MM is deprecated, this commit replaces them
in the hier blocks, gmfsk demod and gfsk demod, with Andy Wall's Symbol
Sync block. Backward compatibility is maintained by keeping the
parameters unchanged, and converting the two gain values to the
corresponding loop bandwidth value that Symbol Sync requires.

Even though `mu` parameter's services is no longer required, we leave it
in the hier block for backward compatibility purposes.

Signed-off-by: Solomon Tan <solomonbstoner@yahoo.com.au>

gr-digital/grc/digital_gfsk_demod.block.yml

@@ -16,7 +16,7 @@ parameters:
     dtype: real
     default: '0.175'
 -   id: mu
-    label: Mu
+    label: Mu (Unused)
     dtype: real
     default: '0.5'
 -   id: omega_relative_limit

gr-digital/grc/digital_gmsk_demod.block.yml

@@ -12,7 +12,7 @@ parameters:
     dtype: real
     default: '0.175'
 -   id: mu
-    label: Mu
+    label: Mu (Unused)
     dtype: real
     default: '0.5'
 -   id: omega_relative_limit

gr-digital/python/digital/gfsk.py

@@ -12,6 +12,7 @@
 
 
 # See gnuradio-examples/python/digital for examples
+from math import log as ln
 
 import numpy
 
@@ -190,7 +191,7 @@ def __init__(self,
 
         Args:
             gain_mu: controls rate of mu adjustment (float)
-            mu: fractional delay [0.0, 1.0] (float)
+            mu: unused but unremoved for backward compatibility (unused)
             omega_relative_limit: sets max variation in omega (float, typically 0.000200 (200 ppm))
             freq_error: bit rate error as a fraction
             float:
@@ -202,7 +203,6 @@ def __init__(self,
 
         self._samples_per_symbol = samples_per_symbol
         self._gain_mu = gain_mu
-        self._mu = mu
         self._omega_relative_limit = omega_relative_limit
         self._freq_error = freq_error
         self._differential = False
@@ -217,15 +217,27 @@ def __init__(self,
 
         self._gain_omega = .25 * self._gain_mu * self._gain_mu        # critically damped
 
+        self._damping = 1.0
+        self._loop_bw = -ln((self._gain_mu + self._gain_omega)/(-2.0) + 1)        # critically damped
+        self._max_dev = self._omega_relative_limit * self._samples_per_symbol
+
         # Demodulate FM
         #sensitivity = (pi / 2) / samples_per_symbol
         self.fmdemod = analog.quadrature_demod_cf(1.0 / sensitivity)
 
         # the clock recovery block tracks the symbol clock and resamples as needed.
         # the output of the block is a stream of soft symbols (float)
-        self.clock_recovery = digital.clock_recovery_mm_ff(self._omega, self._gain_omega,
-                                                           self._mu, self._gain_mu,
-                                                           self._omega_relative_limit)
+        self.clock_recovery = self.digital_symbol_sync_xx_0 = digital.symbol_sync_ff(digital.TED_MUELLER_AND_MULLER,
+                            self._omega,
+                            self._loop_bw,
+                            self._damping,
+                            1.0,  # Expected TED gain
+                            self._max_dev,
+                            1,  # Output sps
+                            digital.constellation_bpsk().base(),
+                            digital.IR_MMSE_8TAP,
+                            128,
+                            [])
 
         # slice the floats at 0, outputting 1 bit (the LSB of the output byte) per sample
         self.slicer = digital.binary_slicer_fb()
@@ -248,10 +260,10 @@ def bits_per_symbol(self=None):   # staticmethod that's also callable on an inst
 
     def _print_verbage(self):
         print("bits per symbol = %d" % self.bits_per_symbol())
-        print("M&M clock recovery omega = %f" % self._omega)
-        print("M&M clock recovery gain mu = %f" % self._gain_mu)
-        print("M&M clock recovery mu = %f" % self._mu)
-        print("M&M clock recovery omega rel. limit = %f" % self._omega_relative_limit)
+        print("Symbol Sync M&M omega = %f" % self._omega)
+        print("Symbol Sync M&M gain mu = %f" % self._gain_mu)
+        print("M&M clock recovery mu (Unused) = %f" % self._mu)
+        print("Symbol Sync M&M omega rel. limit = %f" % self._omega_relative_limit)
         print("frequency error = %f" % self._freq_error)
 
 
@@ -270,13 +282,13 @@ def add_options(parser):
         Adds GFSK demodulation-specific options to the standard parser
         """
         parser.add_option("", "--gain-mu", type="float", default=_def_gain_mu,
-                          help="M&M clock recovery gain mu [default=%default] (GFSK/PSK)")
+                          help="Symbol Sync M&M gain mu [default=%default] (GFSK/PSK)")
         parser.add_option("", "--mu", type="float", default=_def_mu,
-                          help="M&M clock recovery mu [default=%default] (GFSK/PSK)")
+                          help="M&M clock recovery mu [default=%default] (Unused)")
         parser.add_option("", "--omega-relative-limit", type="float", default=_def_omega_relative_limit,
-                          help="M&M clock recovery omega relative limit [default=%default] (GFSK/PSK)")
+                          help="Symbol Sync M&M omega relative limit [default=%default] (GFSK/PSK)")
         parser.add_option("", "--freq-error", type="float", default=_def_freq_error,
-                          help="M&M clock recovery frequency error [default=%default] (GFSK)")
+                          help="Symbol Sync M&M frequency error [default=%default] (GFSK)")
 
     @staticmethod
     def extract_kwargs_from_options(options):

gr-digital/python/digital/gmsk.py

@@ -14,6 +14,7 @@
 # See gnuradio-examples/python/digital for examples
 
 from math import pi
+from math import log as ln
 from pprint import pprint
 import inspect
 
@@ -167,7 +168,7 @@ class gmsk_demod(gr.hier_block2):
     Args:
         samples_per_symbol: samples per baud (integer)
         gain_mu: controls rate of mu adjustment (float)
-        mu: fractional delay [0.0, 1.0] (float)
+        mu: unused but unremoved for backward compatibility (unused)
         omega_relative_limit: sets max variation in omega (float)
         freq_error: bit rate error as a fraction (float)
         verbose: Print information about modulator? (boolean)
@@ -189,7 +190,6 @@ def __init__(self,
 
         self._samples_per_symbol = samples_per_symbol
         self._gain_mu = gain_mu
-        self._mu = mu
         self._omega_relative_limit = omega_relative_limit
         self._freq_error = freq_error
         self._differential = False
@@ -204,15 +204,27 @@ def __init__(self,
 
         self._gain_omega = .25 * self._gain_mu * self._gain_mu        # critically damped
 
+        self._damping = 1.0
+        self._loop_bw = -ln((self._gain_mu + self._gain_omega)/(-2.0) + 1)        # critically damped
+        self._max_dev = self._omega_relative_limit * self._samples_per_symbol
+
         # Demodulate FM
         sensitivity = (pi / 2) / samples_per_symbol
         self.fmdemod = analog.quadrature_demod_cf(1.0 / sensitivity)
 
         # the clock recovery block tracks the symbol clock and resamples as needed.
         # the output of the block is a stream of soft symbols (float)
-        self.clock_recovery = digital.clock_recovery_mm_ff(self._omega, self._gain_omega,
-                                                           self._mu, self._gain_mu,
-                                                           self._omega_relative_limit)
+        self.clock_recovery = self.digital_symbol_sync_xx_0 = digital.symbol_sync_ff(digital.TED_MUELLER_AND_MULLER,
+                            self._omega,
+                            self._loop_bw,
+                            self._damping,
+                            1.0,  # Expected TED gain
+                            self._max_dev,
+                            1,  # Output sps
+                            digital.constellation_bpsk().base(),
+                            digital.IR_MMSE_8TAP,
+                            128,
+                            [])
 
         # slice the floats at 0, outputting 1 bit (the LSB of the output byte) per sample
         self.slicer = digital.binary_slicer_fb()
@@ -235,10 +247,10 @@ def bits_per_symbol(self=None):   # staticmethod that's also callable on an inst
 
     def _print_verbage(self):
         print("bits per symbol = %d" % self.bits_per_symbol())
-        print("M&M clock recovery omega = %f" % self._omega)
-        print("M&M clock recovery gain mu = %f" % self._gain_mu)
-        print("M&M clock recovery mu = %f" % self._mu)
-        print("M&M clock recovery omega rel. limit = %f" % self._omega_relative_limit)
+        print("Symbol Sync M&M omega = %f" % self._omega)
+        print("Symbol Sync M&M gain mu = %f" % self._gain_mu)
+        print("M&M clock recovery mu (Unused) = %f" % self._mu)
+        print("Symbol Sync M&M omega rel. limit = %f" % self._omega_relative_limit)
         print("frequency error = %f" % self._freq_error)
 
 
@@ -257,13 +269,13 @@ def add_options(parser):
         Adds GMSK demodulation-specific options to the standard parser
         """
         parser.add_option("", "--gain-mu", type="float", default=_def_gain_mu,
-                          help="M&M clock recovery gain mu [default=%default] (GMSK/PSK)")
+                          help="Symbol Sync M&M gain mu [default=%default] (GMSK/PSK)")
         parser.add_option("", "--mu", type="float", default=_def_mu,
-                          help="M&M clock recovery mu [default=%default] (GMSK/PSK)")
+                          help="M&M clock recovery mu [default=%default] (Unused)")
         parser.add_option("", "--omega-relative-limit", type="float", default=_def_omega_relative_limit,
-                          help="M&M clock recovery omega relative limit [default=%default] (GMSK/PSK)")
+                          help="Symbol Sync M&M omega relative limit [default=%default] (GMSK/PSK)")
         parser.add_option("", "--freq-error", type="float", default=_def_freq_error,
-                          help="M&M clock recovery frequency error [default=%default] (GMSK)")
+                          help="Symbol Sync M&M frequency error [default=%default] (GMSK)")
 
     @staticmethod
     def extract_kwargs_from_options(options):