diff --git a/grc/gsm_block_tree.xml b/grc/gsm_block_tree.xml
index 85a89c2..0ceec47 100644
--- a/grc/gsm_block_tree.xml
+++ b/grc/gsm_block_tree.xml
@@ -21,6 +21,10 @@
       <block>gsm_clock_offset_control</block>
       <block>gsm_input</block>
     </cat>
+    <cat>
+      <name>Transmitter</name>
+      <block>gsm_txtime_bursts_tagger</block>
+    </cat>
     <cat>
       <name>Logical channels demapping</name>
       <block>gsm_universal_ctrl_chans_demapper</block>
diff --git a/grc/transmitter/gsm_txtime_bursts_tagger.xml b/grc/transmitter/gsm_txtime_bursts_tagger.xml
index 6e72e03..8c3a203 100644
--- a/grc/transmitter/gsm_txtime_bursts_tagger.xml
+++ b/grc/transmitter/gsm_txtime_bursts_tagger.xml
@@ -2,14 +2,14 @@
 <block>
   <name>txtime_bursts_tagger</name>
   <key>gsm_txtime_bursts_tagger</key>
-  <category>GSM</category>
   <import>import grgsm</import>
-  <make>grgsm.txtime_bursts_tagger()</make>
+  <make>grgsm.txtime_bursts_tagger($init_fn, $init_time, $time_hint)</make>
+  <callback>set_time_hint($time_hint)</callback>
 
   <param>
     <name>init_fn</name>
     <key>init_fn</key>
-    <value>20</value>
+    <value>0</value>
     <type>int</type>
     <hide>part</hide>
   </param>
@@ -17,8 +17,16 @@
   <param>
     <name>init_time</name>
     <key>init_time</key>
-    <value>[10 0.1]</value>
-    <type>none</type>
+    <value>0</value>
+    <type>float</type>
+    <hide>part</hide>
+  </param>
+
+  <param>
+    <name>time_hint</name>
+    <key>time_hint</key>
+    <value>0</value>
+    <type>float</type>
     <hide>part</hide>
   </param>
 
@@ -28,6 +36,8 @@
     <optional>1</optional>
   </sink>
 
+
+
   <sink>
     <name>bursts</name>
     <type>message</type>
diff --git a/python/qa_txtime_bursts_tagger.py b/python/qa_txtime_bursts_tagger.py
index 80257fa..bdbf1af 100755
--- a/python/qa_txtime_bursts_tagger.py
+++ b/python/qa_txtime_bursts_tagger.py
@@ -24,6 +24,14 @@
 from gnuradio import gr, gr_unittest
 from gnuradio import blocks
 from txtime_bursts_tagger import txtime_bursts_tagger
+#from transmitter.txtime_bursts_tagger import txtime_bursts_tagger
+from pmt import *
+
+def make_time_hint_msg(time_hint):
+    return cons( dict_add(make_dict(), intern("time_hint"), from_double(time_hint)),PMT_NIL)
+
+def make_fn_time_msg(fn_ref, time_ref):
+    return cons( dict_add(make_dict(), intern("fn_time"), cons(from_uint64(fn_ref), from_double(time_ref))),PMT_NIL)
 
 class qa_txtime_bursts_tagger (gr_unittest.TestCase):
 
@@ -34,9 +42,64 @@ class qa_txtime_bursts_tagger (gr_unittest.TestCase):
         self.tb = None
 
     def test_001_t (self):
-        # set up fg
-        self.tb.run ()
-        # check data
+        tb  = self.tb
+        time_ref = 0
+        fn_ref = 0
+        dut = txtime_bursts_tagger(fn_ref, time_ref)
+
+        framenumbers_input = [1259192, 1076346, 1076242, 235879, 1259218]
+        timeslots_input = [6, 3, 4, 3, 5]
+        bursts_input = [
+            "0001100001000111100111101111100101000100101011000010011110011101001111101100010100111111100000110100011111101011101100100111110011000100010001010000",
+            "0001000101000000001001111110000110010110110111110111101000001101001111101100010100111111001110001001110101110001010001000111011010010001011011000000",
+            "0001001101101101000111001000101011001101001110110001001100111101001111101100010100111111111001001010011010011111010010010101011001001011011100110000",
+            "0000010010100000001001101010100001011100010001101100111111101101001111101100010100111111101101001110100010101110010110101111100010010000110010110000",
+        ]
+        
+        src = grgsm.burst_source(framenumbers_input, timeslots_input, bursts_input)
+        sink = grgsm.burst_sink()
+        
+        self.tb.msg_connect(src, "out", dut, "bursts")
+        self.tb.msg_connect(dut, "bursts", sink, "in")
+        
+        tb.start()
+        tb.wait()
+        print "Dupa"
+        print sink
+        
+        
+#        msg1 = make_msg(1,"lol1")
+#        msg2 = make_msg(1,"lol2")
+#        msg3 = make_msg(2,"lol1")
+#        msg4 = make_msg(2,"lol1")
+#        
+#        port = intern("msgs")
+
+#        tb.msg_connect(g,"msgs",dbg,"store")
+#        #tb.msg_connect(g,"msgs",dbg,"print_pdu")
+
+#        tb.start()
+
+#        g.to_basic_block()._post(port, msg1)
+#        g.to_basic_block()._post(port, msg3)
+#        g.to_basic_block()._post(port, msg2)
+#        g.to_basic_block()._post(port, msg4)
+
+
+
+#        while dbg.num_messages() < 4:
+#            time.sleep(0.1)
+
+#        tb.stop()
+#        tb.wait()
+#        print dbg.get_message(0)
+#        print get_id(dbg.get_message(0))
+#        
+#        self.assertEqual(get_id(dbg.get_message(0)),1)
+#        self.assertEqual(get_id(dbg.get_message(1)),1)
+#        self.assertEqual(get_id(dbg.get_message(2)),2)
+#        self.assertEqual(get_id(dbg.get_message(3)),2)
+
 
 
 if __name__ == '__main__':
diff --git a/python/transmitter/CMakeLists.txt b/python/transmitter/CMakeLists.txt
index 38a8c39..121ac8a 100644
--- a/python/transmitter/CMakeLists.txt
+++ b/python/transmitter/CMakeLists.txt
@@ -17,6 +17,7 @@
 # the Free Software Foundation, Inc., 51 Franklin Street,
 # Boston, MA 02110-1301, USA.
 
-install(FILES
+GR_PYTHON_INSTALL(
+    FILES
     txtime_bursts_tagger.py DESTINATION ${GR_PYTHON_DIR}/grgsm
 )
diff --git a/python/transmitter/txtime_bursts_tagger.py b/python/transmitter/txtime_bursts_tagger.py
index ce57e55..41cb53b 100644
--- a/python/transmitter/txtime_bursts_tagger.py
+++ b/python/transmitter/txtime_bursts_tagger.py
@@ -21,27 +21,55 @@
 # 
 # 
 
-import numpy
 from gnuradio import gr
+from fn_time import fn_time_delta
+import pmt
+import numpy
 
 class txtime_bursts_tagger(gr.basic_block):
     """
     A block that adds txtime metadata to a burst
     """
-    def __init__(self):
+    def __init__(self, init_fn=0, init_time=0, time_hint=None):
         gr.basic_block.__init__(self,
             name="txtime_bursts_tagger",
             in_sig=[],
             out_sig=[])
+        self.set_fn_time_reference(init_fn, init_time)
+        if time_hint is not None:
+            self.set_time_hint(time_hint)
+
         self.message_port_register_in(pmt.intern("fn_time"))
         self.message_port_register_in(pmt.intern("bursts"))
         self.message_port_register_out(pmt.intern("bursts"))
-    
-        self.set_msg_handler(pmt.intern("fn_time"), self.set_fn_time_reference)
-        self.set_msg_handler(pmt.intern("bursts"), self.set_txtime_of_burst)
+
+        self.set_msg_handler(pmt.intern("fn_time"), self.process_fn_time_reference)
+        self.set_msg_handler(pmt.intern("bursts"), self.process_txtime_of_burst)
         
-    def set_fn_time_reference(self, msg):
-        pass
+    def process_fn_time_reference(self, msg):
+        time_hint = pmt.to_python(pmt.dict_ref(pmt.car(msg), (pmt.intern("time_hint"),PMT_NIL)))
+        fn_time = pmt.to_python(pmt.dict_ref(pmt.car(msg), (pmt.intern("fn_time"),PMT_NIL)))
+        if time_hint is not None:
+            self.time_hint = time_hint
+        elif fn_time is not None:
+            self.fn_ref = pmt.car(fn_time)
+            self.time_ref = pmt.cdr(fn_time)
+            self.time_hint = self.time_ref
+            
+    def process_txtime_of_burst(self, msg):
+        burst_with_header = pmt.to_python(pmt.cdr(msg))
+        fn = burst_with_header[11]+burst_with_header[10]*2**8+burst_with_header[9]*2**16+burst_with_header[8]*2**24
+        ts_num = burst_with_header[3]
+        fn_delta, txtime = fn_time_delta(self.fn_ref, self.time_ref, fn, self.time_hint, ts_num)
+        tags_dict = pmt.dict_add(pmt.make_dict(), pmt.intern("txtime"), pmt.from_double(txtime))
+        new_msg = pmt.cons(tags_dict, pmt.cdr(msg))
+        self.message_port_pub(pmt.intern("bursts"), new_msg)
         
-    def set_txtime_of_burst()
-        pass
+    def set_fn_time_reference(self, init_fn, init_time):
+        self.fn_ref = init_fn
+        self.time_ref = init_time
+        self.set_time_hint(init_time)
+
+    def set_time_hint(self, time_hint):
+        self.time_hint = time_hint
+