8 files changed, 71 insertions, 11 deletions
diff --git a/gr-channels/grc/channels_channel_model.xml b/gr-channels/grc/channels_channel_model.xml
index fa881a10b5..909301de94 100644
--- a/gr-channels/grc/channels_channel_model.xml
+++ b/gr-channels/grc/channels_channel_model.xml
@@ -15,6 +15,7 @@
 	epsilon=$epsilon,
 	taps=$taps,
 	noise_seed=$seed,
+	block_tags=$block_tags
 )</make>
 	<callback>set_noise_voltage($noise_voltage)</callback>
 	<callback>set_frequency_offset($freq_offset)</callback>
@@ -50,6 +51,23 @@
 		<value>0</value>
 		<type>int</type>
 	</param>
+	<param>
+		<name>Block Tag Propagation</name>
+		<key>block_tags</key>
+		<value>False</value>
+		<type>enum</type>
+		<hide>$block_tags.hide_block</hide>
+		<option>
+			<name>Yes</name>
+			<key>True</key>
+			<opt>hide_block:</opt>
+		</option>
+		<option>
+			<name>No</name>
+			<key>False</key>
+			<opt>hide_block:part</opt>
+		</option>
+	</param>
 	<sink>
 		<name>in</name>
 		<type>complex</type>
diff --git a/gr-channels/grc/channels_channel_model2.xml b/gr-channels/grc/channels_channel_model2.xml
index e8162f53d4..85355a1029 100644
--- a/gr-channels/grc/channels_channel_model2.xml
+++ b/gr-channels/grc/channels_channel_model2.xml
@@ -14,6 +14,7 @@
 	epsilon=$epsilon,
 	taps=$taps,
 	noise_seed=$seed,
+	block_tags=$block_tags
 )</make>
 	<callback>set_noise_voltage($noise_voltage)</callback>
 	<callback>set_taps($taps)</callback>
@@ -42,6 +43,23 @@
 		<value>0</value>
 		<type>int</type>
 	</param>
+	<param>
+		<name>Block Tag Propagation</name>
+		<key>block_tags</key>
+		<value>False</value>
+		<type>enum</type>
+		<hide>$block_tags.hide_block</hide>
+		<option>
+			<name>Yes</name>
+			<key>True</key>
+			<opt>hide_block:</opt>
+		</option>
+		<option>
+			<name>No</name>
+			<key>False</key>
+			<opt>hide_block:part</opt>
+		</option>
+	</param>
 	<sink>
 		<name>in</name>
 		<type>complex</type>
diff --git a/gr-channels/include/gnuradio/channels/channel_model.h b/gr-channels/include/gnuradio/channels/channel_model.h
index 8b533ac7da..6a1e4a08cb 100644
--- a/gr-channels/include/gnuradio/channels/channel_model.h
+++ b/gr-channels/include/gnuradio/channels/channel_model.h
@@ -43,7 +43,10 @@ namespace gr {
      * the AWGN noise source.
      *
      * Multipath can be approximated in this model by using a FIR
-     * filter representation of a multipath delay profile..
+     * filter representation of a multipath delay profile.
+     *
+     * To simulate a channel with time-variant channel, use a
+     * gr::channels::channel_model2.
      */
     class CHANNELS_API channel_model : virtual public hier_block2
     {
@@ -64,12 +67,14 @@ namespace gr {
        *                the transmitter and receiver. 1.0 is no difference.
        * \param taps Taps of a FIR filter to emulate a multipath delay profile.
        * \param noise_seed A random number generator seed for the noise source.
+       * \param block_tags If true, tags will not be able to propagate through this block.
        */
       static sptr make(double noise_voltage=0.0,
 		       double frequency_offset=0.0,
 		       double epsilon=1.0,
 		       const std::vector<gr_complex> &taps=std::vector<gr_complex>(1,1),
-		       double noise_seed=0);
+		       double noise_seed=0,
+		       bool block_tags=false);
 
       virtual void set_noise_voltage(double noise_voltage) = 0;
       virtual void set_frequency_offset(double frequency_offset) = 0;
diff --git a/gr-channels/include/gnuradio/channels/channel_model2.h b/gr-channels/include/gnuradio/channels/channel_model2.h
index 05084931ee..6c52f34d81 100644
--- a/gr-channels/include/gnuradio/channels/channel_model2.h
+++ b/gr-channels/include/gnuradio/channels/channel_model2.h
@@ -81,11 +81,13 @@ namespace gr {
        *                the transmitter and receiver. 1.0 is no difference.
        * \param taps Taps of a FIR filter to emulate a multipath delay profile.
        * \param noise_seed A random number generator seed for the noise source.
+       * \param block_tags If true, tags will not be able to propagate through this block.
        */
       static sptr make(double noise_voltage=0.0,
 		       double epsilon=1.0,
 		       const std::vector<gr_complex> &taps=std::vector<gr_complex>(1,1),
-		       double noise_seed=0);
+		       double noise_seed=0,
+		       bool block_tags=false);
 
       virtual void set_noise_voltage(double noise_voltage) = 0;
       virtual void set_taps(const std::vector<gr_complex> &taps) = 0;
diff --git a/gr-channels/lib/channel_model2_impl.cc b/gr-channels/lib/channel_model2_impl.cc
index 13eb033def..7533871de2 100644
--- a/gr-channels/lib/channel_model2_impl.cc
+++ b/gr-channels/lib/channel_model2_impl.cc
@@ -33,20 +33,23 @@ namespace gr {
     channel_model2::make(double noise_voltage,
                          double epsilon,
                          const std::vector<gr_complex> &taps,
-                         double noise_seed)
+                         double noise_seed,
+			 bool block_tags)
     {
       return gnuradio::get_initial_sptr
 	(new channel_model2_impl(noise_voltage,
                                  epsilon,
                                  taps,
-                                 noise_seed));
+                                 noise_seed,
+				 block_tags));
     }
 
     // Hierarchical block constructor
     channel_model2_impl::channel_model2_impl(double noise_voltage,
                                              double epsilon,
                                              const std::vector<gr_complex> &taps,
-                                             double noise_seed)
+                                             double noise_seed,
+					     bool block_tags)
     : hier_block2("channel_model2",
                   io_signature::make2(3, 3, sizeof(gr_complex), sizeof(float)),
                   io_signature::make(1, 1, sizeof(gr_complex)))
@@ -78,6 +81,10 @@ namespace gr {
       connect(d_mixer_offset, 0, d_noise_adder, 1);
       connect(d_noise, 0, d_noise_adder, 0);
       connect(d_noise_adder, 0, self(), 0);
+
+      if (block_tags) {
+	d_timing_offset->set_tag_propagation_policy(gr::block::TPP_DONT);
+      }
     }
 
     channel_model2_impl::~channel_model2_impl()
diff --git a/gr-channels/lib/channel_model2_impl.h b/gr-channels/lib/channel_model2_impl.h
index db2a667f9c..3bf1adb44e 100644
--- a/gr-channels/lib/channel_model2_impl.h
+++ b/gr-channels/lib/channel_model2_impl.h
@@ -55,7 +55,8 @@ namespace gr {
       channel_model2_impl(double noise_voltage,
                           double epsilon,
                           const std::vector<gr_complex> &taps,
-                          double noise_seed);
+                          double noise_seed,
+			  bool block_tags);
       
       ~channel_model2_impl();
 
diff --git a/gr-channels/lib/channel_model_impl.cc b/gr-channels/lib/channel_model_impl.cc
index b232f9b235..7db4e6aa5c 100644
--- a/gr-channels/lib/channel_model_impl.cc
+++ b/gr-channels/lib/channel_model_impl.cc
@@ -32,14 +32,16 @@ namespace gr {
 			double frequency_offset,
 			double epsilon,
 			const std::vector<gr_complex> &taps,
-			double noise_seed)
+			double noise_seed,
+			bool block_tags)
     {
       return gnuradio::get_initial_sptr
 	(new channel_model_impl(noise_voltage,
 				frequency_offset,
 				epsilon,
 				taps,
-				noise_seed));
+				noise_seed,
+				block_tags));
     }
 
     // Hierarchical block constructor
@@ -47,7 +49,9 @@ namespace gr {
 					   double frequency_offset,
 					   double epsilon,
 					   const std::vector<gr_complex> &taps,
-					   double noise_seed)
+					   double noise_seed,
+					   bool block_tags
+					   )
       : hier_block2("channel_model",
 		       io_signature::make(1, 1, sizeof(gr_complex)),
 		       io_signature::make(1, 1, sizeof(gr_complex)))
@@ -75,6 +79,10 @@ namespace gr {
       connect(d_mixer_offset, 0, d_noise_adder, 1);
       connect(d_noise, 0, d_noise_adder, 0);
       connect(d_noise_adder, 0, self(), 0);
+
+      if (block_tags) {
+	d_timing_offset->set_tag_propagation_policy(gr::block::TPP_DONT);
+      }
     }
 
     channel_model_impl::~channel_model_impl()
diff --git a/gr-channels/lib/channel_model_impl.h b/gr-channels/lib/channel_model_impl.h
index da00e98da2..3faf6c3bbe 100644
--- a/gr-channels/lib/channel_model_impl.h
+++ b/gr-channels/lib/channel_model_impl.h
@@ -54,7 +54,8 @@ namespace gr {
 			 double frequency_offset,
 			 double epsilon,
 			 const std::vector<gr_complex> &taps,
-			 double noise_seed);
+			 double noise_seed,
+			 bool block_tags);
       
       ~channel_model_impl();