digital: adding a GFSK mod/demodulator.

Includes GRC files and an example in gr-digital/examples/demod

7 files changed, 1124 insertions, 0 deletions

diff --git a/gr-digital/examples/CMakeLists.txt b/gr-digital/examples/CMakeLists.txt
index 33d257e59..63e1eba4e 100644
--- a/gr-digital/examples/CMakeLists.txt
+++ b/gr-digital/examples/CMakeLists.txt
@@ -71,6 +71,7 @@ install(
     demod/pam_timing.grc
     demod/ber_simulation.grc
     demod/dpsk_loopback.grc   
+    demod/gfsk_loopback.grc
     DESTINATION ${GR_PKG_DIGITAL_EXAMPLES_DIR}/demod
     COMPONENT "digital_python"
 )
diff --git a/gr-digital/examples/demod/gfsk_loopback.grc b/gr-digital/examples/demod/gfsk_loopback.grc
new file mode 100644
index 000000000..f74a83526
--- /dev/null
+++ b/gr-digital/examples/demod/gfsk_loopback.grc
@@ -0,0 +1,646 @@
+<?xml version='1.0' encoding='ASCII'?>
+<flow_graph>
+  <timestamp>Sun Jul  8 16:56:18 2012</timestamp>
+  <block>
+    <key>variable_slider</key>
+    <param>
+      <key>id</key>
+      <value>freq</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>label</key>
+      <value>Frequency (Hz)</value>
+    </param>
+    <param>
+      <key>value</key>
+      <value>500</value>
+    </param>
+    <param>
+      <key>min</key>
+      <value>0</value>
+    </param>
+    <param>
+      <key>max</key>
+      <value>samp_rate/2</value>
+    </param>
+    <param>
+      <key>num_steps</key>
+      <value>100</value>
+    </param>
+    <param>
+      <key>style</key>
+      <value>wx.SL_HORIZONTAL</value>
+    </param>
+    <param>
+      <key>converver</key>
+      <value>float_converter</value>
+    </param>
+    <param>
+      <key>grid_pos</key>
+      <value></value>
+    </param>
+    <param>
+      <key>notebook</key>
+      <value></value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(34, 241)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>gr_sig_source_x</key>
+    <param>
+      <key>id</key>
+      <value>gr_sig_source_x_0</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>type</key>
+      <value>float</value>
+    </param>
+    <param>
+      <key>samp_rate</key>
+      <value>samp_rate</value>
+    </param>
+    <param>
+      <key>waveform</key>
+      <value>gr.GR_COS_WAVE</value>
+    </param>
+    <param>
+      <key>freq</key>
+      <value>freq</value>
+    </param>
+    <param>
+      <key>amp</key>
+      <value>1</value>
+    </param>
+    <param>
+      <key>offset</key>
+      <value>0</value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(215, 26)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>gr_throttle</key>
+    <param>
+      <key>id</key>
+      <value>gr_throttle_0_0</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>type</key>
+      <value>float</value>
+    </param>
+    <param>
+      <key>samples_per_second</key>
+      <value>samp_rate</value>
+    </param>
+    <param>
+      <key>vlen</key>
+      <value>1</value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(272.5, 142.0)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>blks2_packet_encoder</key>
+    <param>
+      <key>id</key>
+      <value>blks2_packet_encoder_0</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>type</key>
+      <value>float</value>
+    </param>
+    <param>
+      <key>samples_per_symbol</key>
+      <value>2</value>
+    </param>
+    <param>
+      <key>bits_per_symbol</key>
+      <value>1</value>
+    </param>
+    <param>
+      <key>access_code</key>
+      <value></value>
+    </param>
+    <param>
+      <key>pad_for_usrp</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>payload_length</key>
+      <value>0</value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(261, 227)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>variable</key>
+    <param>
+      <key>id</key>
+      <value>samp_rate</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>value</key>
+      <value>10000</value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(10, 170)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>digital_gfsk_demod</key>
+    <param>
+      <key>id</key>
+      <value>digital_gfsk_demod_0</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>samples_per_symbol</key>
+      <value>sps</value>
+    </param>
+    <param>
+      <key>sensitivity</key>
+      <value>fm_sensitivity</value>
+    </param>
+    <param>
+      <key>gain_mu</key>
+      <value>0.175</value>
+    </param>
+    <param>
+      <key>mu</key>
+      <value>0.5</value>
+    </param>
+    <param>
+      <key>omega_relative_limit</key>
+      <value>0.005</value>
+    </param>
+    <param>
+      <key>freq_error</key>
+      <value>0.0</value>
+    </param>
+    <param>
+      <key>verbose</key>
+      <value>False</value>
+    </param>
+    <param>
+      <key>log</key>
+      <value>False</value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(669, 257)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>variable</key>
+    <param>
+      <key>id</key>
+      <value>sps</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>value</key>
+      <value>8</value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(47, 445)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>digital_gfsk_mod</key>
+    <param>
+      <key>id</key>
+      <value>digital_gfsk_mod_0</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>samples_per_symbol</key>
+      <value>sps</value>
+    </param>
+    <param>
+      <key>sensitivity</key>
+      <value>fm_sensitivity</value>
+    </param>
+    <param>
+      <key>bt</key>
+      <value>0.35</value>
+    </param>
+    <param>
+      <key>verbose</key>
+      <value>False</value>
+    </param>
+    <param>
+      <key>log</key>
+      <value>False</value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(456, 277)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>variable</key>
+    <param>
+      <key>id</key>
+      <value>fm_sensitivity</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>value</key>
+      <value>1.0</value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(40, 366)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>blks2_packet_decoder</key>
+    <param>
+      <key>id</key>
+      <value>blks2_packet_decoder_0</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>type</key>
+      <value>float</value>
+    </param>
+    <param>
+      <key>access_code</key>
+      <value></value>
+    </param>
+    <param>
+      <key>threshold</key>
+      <value>-1</value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(705, 130)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>gr_quadrature_demod_cf</key>
+    <param>
+      <key>id</key>
+      <value>gr_quadrature_demod_cf_0</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>gain</key>
+      <value>1</value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(627, 417)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>options</key>
+    <param>
+      <key>id</key>
+      <value>gfsk_loopback</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>title</key>
+      <value></value>
+    </param>
+    <param>
+      <key>author</key>
+      <value></value>
+    </param>
+    <param>
+      <key>description</key>
+      <value></value>
+    </param>
+    <param>
+      <key>window_size</key>
+      <value>1280, 1024</value>
+    </param>
+    <param>
+      <key>generate_options</key>
+      <value>wx_gui</value>
+    </param>
+    <param>
+      <key>category</key>
+      <value>Custom</value>
+    </param>
+    <param>
+      <key>run_options</key>
+      <value>prompt</value>
+    </param>
+    <param>
+      <key>run</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>max_nouts</key>
+      <value>0</value>
+    </param>
+    <param>
+      <key>realtime_scheduling</key>
+      <value></value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(10, 10)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>wxgui_scopesink2</key>
+    <param>
+      <key>id</key>
+      <value>wxgui_scopesink2_0</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>type</key>
+      <value>float</value>
+    </param>
+    <param>
+      <key>title</key>
+      <value>Scope Plot</value>
+    </param>
+    <param>
+      <key>samp_rate</key>
+      <value>samp_rate</value>
+    </param>
+    <param>
+      <key>v_scale</key>
+      <value>0</value>
+    </param>
+    <param>
+      <key>v_offset</key>
+      <value>0</value>
+    </param>
+    <param>
+      <key>t_scale</key>
+      <value>1./freq</value>
+    </param>
+    <param>
+      <key>ac_couple</key>
+      <value>False</value>
+    </param>
+    <param>
+      <key>xy_mode</key>
+      <value>False</value>
+    </param>
+    <param>
+      <key>num_inputs</key>
+      <value>1</value>
+    </param>
+    <param>
+      <key>win_size</key>
+      <value></value>
+    </param>
+    <param>
+      <key>grid_pos</key>
+      <value></value>
+    </param>
+    <param>
+      <key>notebook</key>
+      <value></value>
+    </param>
+    <param>
+      <key>trig_mode</key>
+      <value>gr.gr_TRIG_MODE_AUTO</value>
+    </param>
+    <param>
+      <key>y_axis_label</key>
+      <value>Counts</value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(907, 59)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>wxgui_scopesink2</key>
+    <param>
+      <key>id</key>
+      <value>wxgui_scopesink2_1</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>type</key>
+      <value>float</value>
+    </param>
+    <param>
+      <key>title</key>
+      <value>Scope Plot</value>
+    </param>
+    <param>
+      <key>samp_rate</key>
+      <value>samp_rate</value>
+    </param>
+    <param>
+      <key>v_scale</key>
+      <value>0</value>
+    </param>
+    <param>
+      <key>v_offset</key>
+      <value>0</value>
+    </param>
+    <param>
+      <key>t_scale</key>
+      <value>0</value>
+    </param>
+    <param>
+      <key>ac_couple</key>
+      <value>False</value>
+    </param>
+    <param>
+      <key>xy_mode</key>
+      <value>False</value>
+    </param>
+    <param>
+      <key>num_inputs</key>
+      <value>1</value>
+    </param>
+    <param>
+      <key>win_size</key>
+      <value></value>
+    </param>
+    <param>
+      <key>grid_pos</key>
+      <value></value>
+    </param>
+    <param>
+      <key>notebook</key>
+      <value></value>
+    </param>
+    <param>
+      <key>trig_mode</key>
+      <value>gr.gr_TRIG_MODE_AUTO</value>
+    </param>
+    <param>
+      <key>y_axis_label</key>
+      <value>Counts</value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(853, 400)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <connection>
+    <source_block_id>digital_gfsk_mod_0</source_block_id>
+    <sink_block_id>digital_gfsk_demod_0</sink_block_id>
+    <source_key>0</source_key>
+    <sink_key>0</sink_key>
+  </connection>
+  <connection>
+    <source_block_id>gr_sig_source_x_0</source_block_id>
+    <sink_block_id>gr_throttle_0_0</sink_block_id>
+    <source_key>0</source_key>
+    <sink_key>0</sink_key>
+  </connection>
+  <connection>
+    <source_block_id>gr_throttle_0_0</source_block_id>
+    <sink_block_id>blks2_packet_encoder_0</sink_block_id>
+    <source_key>0</source_key>
+    <sink_key>0</sink_key>
+  </connection>
+  <connection>
+    <source_block_id>blks2_packet_encoder_0</source_block_id>
+    <sink_block_id>digital_gfsk_mod_0</sink_block_id>
+    <source_key>0</source_key>
+    <sink_key>0</sink_key>
+  </connection>
+  <connection>
+    <source_block_id>digital_gfsk_demod_0</source_block_id>
+    <sink_block_id>blks2_packet_decoder_0</sink_block_id>
+    <source_key>0</source_key>
+    <sink_key>0</sink_key>
+  </connection>
+  <connection>
+    <source_block_id>blks2_packet_decoder_0</source_block_id>
+    <sink_block_id>wxgui_scopesink2_0</sink_block_id>
+    <source_key>0</source_key>
+    <sink_key>0</sink_key>
+  </connection>
+  <connection>
+    <source_block_id>digital_gfsk_mod_0</source_block_id>
+    <sink_block_id>gr_quadrature_demod_cf_0</sink_block_id>
+    <source_key>0</source_key>
+    <sink_key>0</sink_key>
+  </connection>
+  <connection>
+    <source_block_id>gr_quadrature_demod_cf_0</source_block_id>
+    <sink_block_id>wxgui_scopesink2_1</sink_block_id>
+    <source_key>0</source_key>
+    <sink_key>0</sink_key>
+  </connection>
+</flow_graph>
diff --git a/gr-digital/grc/digital_gfsk_demod.xml b/gr-digital/grc/digital_gfsk_demod.xml
new file mode 100644
index 000000000..ce3024d89
--- /dev/null
+++ b/gr-digital/grc/digital_gfsk_demod.xml
@@ -0,0 +1,95 @@
+<?xml version="1.0"?>
+<!--
+###################################################
+##GFSK Demod
+###################################################
+ -->
+<block>
+	<name>GFSK Demod</name>
+	<key>digital_gfsk_demod</key>
+	<import>from gnuradio import digital</import>
+	<make>digital.gfsk_demod(
+	samples_per_symbol=$samples_per_symbol,
+	sensitivity=$sensitivity,
+	gain_mu=$gain_mu,
+	mu=$mu,
+	omega_relative_limit=$omega_relative_limit,
+	freq_error=$freq_error,
+	verbose=$verbose,
+	log=$log,
+)</make>
+	<param>
+		<name>Samples/Symbol</name>
+		<key>samples_per_symbol</key>
+		<value>2</value>
+		<type>int</type>
+	</param>
+	<param>
+		<name>Sensitivity</name>
+		<key>sensitivity</key>
+		<value>1.0</value>
+		<type>real</type>
+	</param>
+	<param>
+		<name>Gain Mu</name>
+		<key>gain_mu</key>
+		<value>0.175</value>
+		<type>real</type>
+	</param>
+	<param>
+		<name>Mu</name>
+		<key>mu</key>
+		<value>0.5</value>
+		<type>real</type>
+	</param>
+	<param>
+		<name>Omega Relative Limit</name>
+		<key>omega_relative_limit</key>
+		<value>0.005</value>
+		<type>real</type>
+	</param>
+	<param>
+		<name>Freq Error</name>
+		<key>freq_error</key>
+		<value>0.0</value>
+		<type>real</type>
+	</param>
+	<param>
+		<name>Verbose</name>
+		<key>verbose</key>
+		<value>False</value>
+		<type>bool</type>
+		<hide>#if str($verbose) == 'False' then 'part' else 'none'#</hide>
+		<option>
+			<name>On</name>
+			<key>True</key>
+		</option>
+		<option>
+			<name>Off</name>
+			<key>False</key>
+		</option>
+	</param>
+	<param>
+		<name>Logging</name>
+		<key>log</key>
+		<value>False</value>
+		<type>bool</type>
+		<hide>#if str($log) == 'False' then 'part' else 'none'#</hide>
+		<option>
+			<name>On</name>
+			<key>True</key>
+		</option>
+		<option>
+			<name>Off</name>
+			<key>False</key>
+		</option>
+	</param>
+	<sink>
+		<name>in</name>
+		<type>complex</type>
+	</sink>
+	<source>
+		<name>out</name>
+		<type>byte</type>
+	</source>
+</block>
diff --git a/gr-digital/grc/digital_gfsk_mod.xml b/gr-digital/grc/digital_gfsk_mod.xml
new file mode 100644
index 000000000..2d6cd1ea5
--- /dev/null
+++ b/gr-digital/grc/digital_gfsk_mod.xml
@@ -0,0 +1,74 @@
+<?xml version="1.0"?>
+<!--
+###################################################
+##GFSK Mod
+###################################################
+ -->
+<block>
+	<name>GFSK Mod</name>
+	<key>digital_gfsk_mod</key>
+	<import>from gnuradio import digital</import>
+	<make>digital.gfsk_mod(
+	samples_per_symbol=$samples_per_symbol,
+	sensitivity=$sensitivity,
+	bt=$bt,
+	verbose=$verbose,
+	log=$log,
+)</make>
+	<param>
+		<name>Samples/Symbol</name>
+		<key>samples_per_symbol</key>
+		<value>2</value>
+		<type>int</type>
+	</param>
+	<param>
+		<name>Sensitivity</name>
+		<key>sensitivity</key>
+		<value>1.0</value>
+		<type>real</type>
+	</param>
+	<param>
+		<name>BT</name>
+		<key>bt</key>
+		<value>0.35</value>
+		<type>real</type>
+	</param>
+	<param>
+		<name>Verbose</name>
+		<key>verbose</key>
+		<value>False</value>
+		<type>bool</type>
+		<hide>#if str($verbose) == 'False' then 'part' else 'none'#</hide>
+		<option>
+			<name>On</name>
+			<key>True</key>
+		</option>
+		<option>
+			<name>Off</name>
+			<key>False</key>
+		</option>
+	</param>
+	<param>
+		<name>Logging</name>
+		<key>log</key>
+		<value>False</value>
+		<type>bool</type>
+		<hide>#if str($log) == 'False' then 'part' else 'none'#</hide>
+		<option>
+			<name>On</name>
+			<key>True</key>
+		</option>
+		<option>
+			<name>Off</name>
+			<key>False</key>
+		</option>
+	</param>
+	<sink>
+		<name>in</name>
+		<type>byte</type>
+	</sink>
+	<source>
+		<name>out</name>
+		<type>complex</type>
+	</source>
+</block>
diff --git a/gr-digital/python/CMakeLists.txt b/gr-digital/python/CMakeLists.txt
index c786b5a14..6a9f10295 100644
--- a/gr-digital/python/CMakeLists.txt
+++ b/gr-digital/python/CMakeLists.txt
@@ -30,6 +30,7 @@ GR_PYTHON_INSTALL(
     crc.py
     generic_mod_demod.py
     gmsk.py
+    gfsk.py
     modulation_utils.py
     ofdm.py
     ofdm_packet_utils.py
diff --git a/gr-digital/python/__init__.py b/gr-digital/python/__init__.py
index 7c76183c9..3fdbca769 100644
--- a/gr-digital/python/__init__.py
+++ b/gr-digital/python/__init__.py
@@ -31,6 +31,7 @@ from qam import *
 from bpsk import *
 from qpsk import *
 from gmsk import *
+from gfsk import *
 from cpm import *
 from pkt import *
 from crc import *
diff --git a/gr-digital/python/gfsk.py b/gr-digital/python/gfsk.py
new file mode 100644
index 000000000..c85fdf0e0
--- /dev/null
+++ b/gr-digital/python/gfsk.py
@@ -0,0 +1,306 @@
+#
+# GFSK modulation and demodulation.  
+#
+#
+# Copyright 2005,2006,2007 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.
+# 
+
+# See gnuradio-examples/python/digital for examples
+
+from gnuradio import gr
+import modulation_utils
+import digital_swig as digital
+from math import pi
+import numpy
+from pprint import pprint
+import inspect
+
+# default values (used in __init__ and add_options)
+_def_samples_per_symbol = 2
+_def_sensitivity = 1
+_def_bt = 0.35
+_def_verbose = False
+_def_log = False
+
+_def_gain_mu = None
+_def_mu = 0.5
+_def_freq_error = 0.0
+_def_omega_relative_limit = 0.005
+
+
+# FIXME: Figure out how to make GFSK work with pfb_arb_resampler_fff for both
+# transmit and receive so we don't require integer samples per symbol.
+
+
+# /////////////////////////////////////////////////////////////////////////////
+#                              GFSK modulator
+# /////////////////////////////////////////////////////////////////////////////
+
+class gfsk_mod(gr.hier_block2):
+
+    def __init__(self,
+                 samples_per_symbol=_def_samples_per_symbol,
+                 sensitivity=_def_sensitivity,
+                 bt=_def_bt,
+                 verbose=_def_verbose,
+                 log=_def_log):
+        """
+	Hierarchical block for Gaussian Frequency Shift Key (GFSK)
+	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 baud >= 2
+	@type samples_per_symbol: integer
+	@param bt: Gaussian filter bandwidth * symbol time
+	@type bt: 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, "gfsk_mod",
+				gr.io_signature(1, 1, gr.sizeof_char),       # Input signature
+				gr.io_signature(1, 1, gr.sizeof_gr_complex)) # Output signature
+
+        samples_per_symbol = int(samples_per_symbol)
+        self._samples_per_symbol = samples_per_symbol
+        self._bt = bt
+        self._differential = False
+
+        if not isinstance(samples_per_symbol, int) or samples_per_symbol < 2:
+            raise TypeError, ("samples_per_symbol must be an integer >= 2, is %r" % (samples_per_symbol,))
+
+	ntaps = 4 * samples_per_symbol			# up to 3 bits in filter at once
+	#sensitivity = (pi / 2) / samples_per_symbol	# phase change per bit = pi / 2
+
+	# Turn it into NRZ data.
+	self.nrz = gr.bytes_to_syms()
+
+	# Form Gaussian filter
+        # Generate Gaussian response (Needs to be convolved with window below).
+	self.gaussian_taps = gr.firdes.gaussian(
+		1.0,		       # gain
+		samples_per_symbol,    # symbol_rate
+		bt,		       # bandwidth * symbol time
+		ntaps	               # number of taps
+		)
+
+	self.sqwave = (1,) * samples_per_symbol       # rectangular window
+	self.taps = numpy.convolve(numpy.array(self.gaussian_taps),numpy.array(self.sqwave))
+	self.gaussian_filter = gr.interp_fir_filter_fff(samples_per_symbol, self.taps)
+
+	# FM modulation
+	self.fmmod = gr.frequency_modulator_fc(sensitivity)
+
+	# small amount of output attenuation to prevent clipping USRP sink
+	self.amp = gr.multiply_const_cc(0.999)
+		
+        if verbose:
+            self._print_verbage()
+         
+        if log:
+            self._setup_logging()
+
+	# Connect & Initialize base class
+	self.connect(self, self.nrz, self.gaussian_filter, self.fmmod, self.amp, 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 1
+    bits_per_symbol = staticmethod(bits_per_symbol)      # make it a static method.
+
+
+    def _print_verbage(self):
+        print "bits per symbol = %d" % self.bits_per_symbol()
+        print "Gaussian filter bt = %.2f" % self._bt
+
+
+    def _setup_logging(self):
+        print "Modulation logging turned on."
+        self.connect(self.nrz,
+                     gr.file_sink(gr.sizeof_float, "nrz.dat"))
+        self.connect(self.gaussian_filter,
+                     gr.file_sink(gr.sizeof_float, "gaussian_filter.dat"))
+        self.connect(self.fmmod,
+                     gr.file_sink(gr.sizeof_gr_complex, "fmmod.dat"))
+
+
+    def add_options(parser):
+        """
+        Adds GFSK modulation-specific options to the standard parser
+        """
+        parser.add_option("", "--bt", type="float", default=_def_bt,
+                          help="set bandwidth-time product [default=%default] (GFSK)")
+    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(gfsk_mod.__init__,
+                                                            ('self',), options)
+    extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
+
+
+
+# /////////////////////////////////////////////////////////////////////////////
+#                            GFSK demodulator
+# /////////////////////////////////////////////////////////////////////////////
+
+class gfsk_demod(gr.hier_block2):
+
+    def __init__(self,
+                 samples_per_symbol=_def_samples_per_symbol,
+                 sensitivity=_def_sensitivity,
+                 gain_mu=_def_gain_mu,
+                 mu=_def_mu,
+                 omega_relative_limit=_def_omega_relative_limit,
+                 freq_error=_def_freq_error,
+                 verbose=_def_verbose,
+                 log=_def_log):
+        """
+	Hierarchical block for Gaussian Minimum Shift Key (GFSK)
+	demodulation.
+
+	The input is the complex modulated signal at baseband.
+	The output is a stream of bits packed 1 bit per byte (the LSB)
+
+	@param samples_per_symbol: samples per baud
+	@type samples_per_symbol: integer
+        @param verbose: Print information about modulator?
+        @type verbose: bool
+        @param log: Print modualtion data to files?
+        @type log: bool 
+
+        Clock recovery parameters.  These all have reasonble defaults.
+        
+        @param gain_mu: controls rate of mu adjustment
+        @type gain_mu: float
+        @param mu: fractional delay [0.0, 1.0]
+        @type mu: float
+        @param omega_relative_limit: sets max variation in omega
+        @type omega_relative_limit: float, typically 0.000200 (200 ppm)
+        @param freq_error: bit rate error as a fraction
+        @param float
+	"""
+
+	gr.hier_block2.__init__(self, "gfsk_demod",
+				gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
+				gr.io_signature(1, 1, gr.sizeof_char))       # Output signature
+
+        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
+        
+        if samples_per_symbol < 2:
+            raise TypeError, "samples_per_symbol >= 2, is %f" % samples_per_symbol
+
+        self._omega = samples_per_symbol*(1+self._freq_error)
+
+        if not self._gain_mu:
+            self._gain_mu = 0.175
+            
+	self._gain_omega = .25 * self._gain_mu * self._gain_mu        # critically damped
+
+	# Demodulate FM
+	#sensitivity = (pi / 2) / samples_per_symbol
+	self.fmdemod = gr.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)
+
+        # slice the floats at 0, outputting 1 bit (the LSB of the output byte) per sample
+        self.slicer = digital.binary_slicer_fb()
+
+        if verbose:
+            self._print_verbage()
+         
+        if log:
+            self._setup_logging()
+
+	# Connect & Initialize base class
+	self.connect(self, self.fmdemod, self.clock_recovery, self.slicer, 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 1
+    bits_per_symbol = staticmethod(bits_per_symbol)      # make it a static method.
+
+
+    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 "frequency error = %f" % self._freq_error
+
+
+    def _setup_logging(self):
+        print "Demodulation logging turned on."
+        self.connect(self.fmdemod,
+                    gr.file_sink(gr.sizeof_float, "fmdemod.dat"))
+        self.connect(self.clock_recovery,
+                    gr.file_sink(gr.sizeof_float, "clock_recovery.dat"))
+        self.connect(self.slicer,
+                    gr.file_sink(gr.sizeof_char, "slicer.dat"))
+
+    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)")
+        parser.add_option("", "--mu", type="float", default=_def_mu,
+                          help="M&M clock recovery mu [default=%default] (GFSK/PSK)")
+        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)")
+        parser.add_option("", "--freq-error", type="float", default=_def_freq_error,
+                          help="M&M clock recovery frequency error [default=%default] (GFSK)")
+    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(gfsk_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('gfsk', gfsk_mod)
+modulation_utils.add_type_1_demod('gfsk', gfsk_demod)