Added gain, fc (carrier frequency) and sample frequency parameters to the rtlsdr and usrp apps.
diff --git a/apps/airprobe_usrp.grc b/apps/airprobe_usrp.grc
index 826c18d..08ec368 100644
--- a/apps/airprobe_usrp.grc
+++ b/apps/airprobe_usrp.grc
@@ -26,7 +26,7 @@
     </param>
     <param>
       <key>window_size</key>
-      <value>1280, 1024</value>
+      <value>2280, 1024</value>
     </param>
     <param>
       <key>generate_options</key>
@@ -69,33 +69,6 @@
     <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>100e6/100</value>
-    </param>
-    <param>
-      <key>alias</key>
-      <value></value>
-    </param>
-    <param>
-      <key>_coordinate</key>
-      <value>(16, 99)</value>
-    </param>
-    <param>
-      <key>_rotation</key>
-      <value>0</value>
-    </param>
-  </block>
-  <block>
-    <key>variable</key>
-    <param>
-      <key>id</key>
       <value>CHANNEL_UNKNOWN</value>
     </param>
     <param>
@@ -112,142 +85,7 @@
     </param>
     <param>
       <key>_coordinate</key>
-      <value>(608, 11)</value>
-    </param>
-    <param>
-      <key>_rotation</key>
-      <value>0</value>
-    </param>
-  </block>
-  <block>
-    <key>variable</key>
-    <param>
-      <key>id</key>
-      <value>BCCH</value>
-    </param>
-    <param>
-      <key>_enabled</key>
-      <value>True</value>
-    </param>
-    <param>
-      <key>value</key>
-      <value>1</value>
-    </param>
-    <param>
-      <key>alias</key>
-      <value></value>
-    </param>
-    <param>
-      <key>_coordinate</key>
-      <value>(752, 11)</value>
-    </param>
-    <param>
-      <key>_rotation</key>
-      <value>0</value>
-    </param>
-  </block>
-  <block>
-    <key>variable</key>
-    <param>
-      <key>id</key>
-      <value>CCCH</value>
-    </param>
-    <param>
-      <key>_enabled</key>
-      <value>True</value>
-    </param>
-    <param>
-      <key>value</key>
-      <value>2</value>
-    </param>
-    <param>
-      <key>alias</key>
-      <value></value>
-    </param>
-    <param>
-      <key>_coordinate</key>
-      <value>(824, 11)</value>
-    </param>
-    <param>
-      <key>_rotation</key>
-      <value>0</value>
-    </param>
-  </block>
-  <block>
-    <key>variable</key>
-    <param>
-      <key>id</key>
-      <value>SDCCH</value>
-    </param>
-    <param>
-      <key>_enabled</key>
-      <value>True</value>
-    </param>
-    <param>
-      <key>value</key>
-      <value>6</value>
-    </param>
-    <param>
-      <key>alias</key>
-      <value></value>
-    </param>
-    <param>
-      <key>_coordinate</key>
-      <value>(1112, 11)</value>
-    </param>
-    <param>
-      <key>_rotation</key>
-      <value>0</value>
-    </param>
-  </block>
-  <block>
-    <key>variable</key>
-    <param>
-      <key>id</key>
-      <value>AGCH</value>
-    </param>
-    <param>
-      <key>_enabled</key>
-      <value>True</value>
-    </param>
-    <param>
-      <key>value</key>
-      <value>4</value>
-    </param>
-    <param>
-      <key>alias</key>
-      <value></value>
-    </param>
-    <param>
-      <key>_coordinate</key>
-      <value>(968, 11)</value>
-    </param>
-    <param>
-      <key>_rotation</key>
-      <value>0</value>
-    </param>
-  </block>
-  <block>
-    <key>variable</key>
-    <param>
-      <key>id</key>
-      <value>RACH</value>
-    </param>
-    <param>
-      <key>_enabled</key>
-      <value>True</value>
-    </param>
-    <param>
-      <key>value</key>
-      <value>3</value>
-    </param>
-    <param>
-      <key>alias</key>
-      <value></value>
-    </param>
-    <param>
-      <key>_coordinate</key>
-      <value>(896, 11)</value>
+      <value>(632, 11)</value>
     </param>
     <param>
       <key>_rotation</key>
@@ -274,7 +112,142 @@
     </param>
     <param>
       <key>_coordinate</key>
-      <value>(1040, 11)</value>
+      <value>(1064, 11)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>variable</key>
+    <param>
+      <key>id</key>
+      <value>RACH</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>value</key>
+      <value>3</value>
+    </param>
+    <param>
+      <key>alias</key>
+      <value></value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(920, 11)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>variable</key>
+    <param>
+      <key>id</key>
+      <value>AGCH</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>value</key>
+      <value>4</value>
+    </param>
+    <param>
+      <key>alias</key>
+      <value></value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(992, 11)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>variable</key>
+    <param>
+      <key>id</key>
+      <value>CCCH</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>value</key>
+      <value>2</value>
+    </param>
+    <param>
+      <key>alias</key>
+      <value></value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(848, 11)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>variable</key>
+    <param>
+      <key>id</key>
+      <value>BCCH</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>value</key>
+      <value>1</value>
+    </param>
+    <param>
+      <key>alias</key>
+      <value></value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(776, 11)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>variable</key>
+    <param>
+      <key>id</key>
+      <value>SDCCH</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>value</key>
+      <value>6</value>
+    </param>
+    <param>
+      <key>alias</key>
+      <value></value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(1136, 11)</value>
     </param>
     <param>
       <key>_rotation</key>
@@ -415,124 +388,6 @@
     </param>
   </block>
   <block>
-    <key>variable_qtgui_range</key>
-    <param>
-      <key>id</key>
-      <value>g</value>
-    </param>
-    <param>
-      <key>_enabled</key>
-      <value>True</value>
-    </param>
-    <param>
-      <key>label</key>
-      <value>Gain</value>
-    </param>
-    <param>
-      <key>value</key>
-      <value>30</value>
-    </param>
-    <param>
-      <key>start</key>
-      <value>0</value>
-    </param>
-    <param>
-      <key>stop</key>
-      <value>50</value>
-    </param>
-    <param>
-      <key>step</key>
-      <value>0.5</value>
-    </param>
-    <param>
-      <key>widget</key>
-      <value>counter</value>
-    </param>
-    <param>
-      <key>orient</key>
-      <value>Qt.Horizontal</value>
-    </param>
-    <param>
-      <key>min_len</key>
-      <value>100</value>
-    </param>
-    <param>
-      <key>gui_hint</key>
-      <value></value>
-    </param>
-    <param>
-      <key>alias</key>
-      <value></value>
-    </param>
-    <param>
-      <key>_coordinate</key>
-      <value>(192, 11)</value>
-    </param>
-    <param>
-      <key>_rotation</key>
-      <value>0</value>
-    </param>
-  </block>
-  <block>
-    <key>variable_qtgui_range</key>
-    <param>
-      <key>id</key>
-      <value>ppm</value>
-    </param>
-    <param>
-      <key>_enabled</key>
-      <value>False</value>
-    </param>
-    <param>
-      <key>label</key>
-      <value>PPM Offset</value>
-    </param>
-    <param>
-      <key>value</key>
-      <value>84</value>
-    </param>
-    <param>
-      <key>start</key>
-      <value>-100</value>
-    </param>
-    <param>
-      <key>stop</key>
-      <value>100</value>
-    </param>
-    <param>
-      <key>step</key>
-      <value>1</value>
-    </param>
-    <param>
-      <key>widget</key>
-      <value>counter</value>
-    </param>
-    <param>
-      <key>orient</key>
-      <value>Qt.Horizontal</value>
-    </param>
-    <param>
-      <key>min_len</key>
-      <value>100</value>
-    </param>
-    <param>
-      <key>gui_hint</key>
-      <value></value>
-    </param>
-    <param>
-      <key>alias</key>
-      <value></value>
-    </param>
-    <param>
-      <key>_coordinate</key>
-      <value>(440, 11)</value>
-    </param>
-    <param>
-      <key>_rotation</key>
-      <value>0</value>
-    </param>
-  </block>
-  <block>
     <key>gsm_input</key>
     <param>
       <key>id</key>
@@ -869,6 +724,10 @@
       <value>True</value>
     </param>
     <param>
+      <key>prepend_string</key>
+      <value></value>
+    </param>
+    <param>
       <key>alias</key>
       <value></value>
     </param>
@@ -937,6 +796,202 @@
     </param>
   </block>
   <block>
+    <key>variable_qtgui_range</key>
+    <param>
+      <key>id</key>
+      <value>g_slider</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>label</key>
+      <value>Gain</value>
+    </param>
+    <param>
+      <key>value</key>
+      <value>gain</value>
+    </param>
+    <param>
+      <key>start</key>
+      <value>0</value>
+    </param>
+    <param>
+      <key>stop</key>
+      <value>50</value>
+    </param>
+    <param>
+      <key>step</key>
+      <value>0.5</value>
+    </param>
+    <param>
+      <key>widget</key>
+      <value>counter</value>
+    </param>
+    <param>
+      <key>orient</key>
+      <value>Qt.Horizontal</value>
+    </param>
+    <param>
+      <key>min_len</key>
+      <value>100</value>
+    </param>
+    <param>
+      <key>gui_hint</key>
+      <value></value>
+    </param>
+    <param>
+      <key>alias</key>
+      <value></value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(176, 11)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>variable_qtgui_range</key>
+    <param>
+      <key>id</key>
+      <value>fc_slider</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>label</key>
+      <value>Frequency</value>
+    </param>
+    <param>
+      <key>value</key>
+      <value>fc</value>
+    </param>
+    <param>
+      <key>start</key>
+      <value>925e6</value>
+    </param>
+    <param>
+      <key>stop</key>
+      <value>960e6</value>
+    </param>
+    <param>
+      <key>step</key>
+      <value>2e5</value>
+    </param>
+    <param>
+      <key>widget</key>
+      <value>counter_slider</value>
+    </param>
+    <param>
+      <key>orient</key>
+      <value>Qt.Horizontal</value>
+    </param>
+    <param>
+      <key>min_len</key>
+      <value>100</value>
+    </param>
+    <param>
+      <key>gui_hint</key>
+      <value></value>
+    </param>
+    <param>
+      <key>alias</key>
+      <value></value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(288, 11)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>parameter</key>
+    <param>
+      <key>id</key>
+      <value>gain</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>label</key>
+      <value>gain</value>
+    </param>
+    <param>
+      <key>value</key>
+      <value>30</value>
+    </param>
+    <param>
+      <key>type</key>
+      <value>eng_float</value>
+    </param>
+    <param>
+      <key>short_id</key>
+      <value>g</value>
+    </param>
+    <param>
+      <key>alias</key>
+      <value></value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(424, 11)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
+    <key>parameter</key>
+    <param>
+      <key>id</key>
+      <value>fc</value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>label</key>
+      <value>fc</value>
+    </param>
+    <param>
+      <key>value</key>
+      <value>939.4e6</value>
+    </param>
+    <param>
+      <key>type</key>
+      <value>eng_float</value>
+    </param>
+    <param>
+      <key>short_id</key>
+      <value>f</value>
+    </param>
+    <param>
+      <key>alias</key>
+      <value></value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(504, 11)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+  </block>
+  <block>
     <key>uhd_usrp_source</key>
     <param>
       <key>id</key>
@@ -1088,11 +1143,11 @@
     </param>
     <param>
       <key>center_freq0</key>
-      <value>fc</value>
+      <value>fc_slider</value>
     </param>
     <param>
       <key>gain0</key>
-      <value>g</value>
+      <value>g_slider</value>
     </param>
     <param>
       <key>ant0</key>
@@ -1624,37 +1679,10 @@
     </param>
   </block>
   <block>
-    <key>blocks_message_debug</key>
+    <key>parameter</key>
     <param>
       <key>id</key>
-      <value>blocks_message_debug_0</value>
-    </param>
-    <param>
-      <key>_enabled</key>
-      <value>True</value>
-    </param>
-    <param>
-      <key>alias</key>
-      <value></value>
-    </param>
-    <param>
-      <key>affinity</key>
-      <value></value>
-    </param>
-    <param>
-      <key>_coordinate</key>
-      <value>(672, 400)</value>
-    </param>
-    <param>
-      <key>_rotation</key>
-      <value>0</value>
-    </param>
-  </block>
-  <block>
-    <key>variable_qtgui_range</key>
-    <param>
-      <key>id</key>
-      <value>fc</value>
+      <value>samp_rate</value>
     </param>
     <param>
       <key>_enabled</key>
@@ -1662,39 +1690,19 @@
     </param>
     <param>
       <key>label</key>
-      <value>Frequency</value>
+      <value>samp_rate</value>
     </param>
     <param>
       <key>value</key>
-      <value>1869e6</value>
+      <value>2000000.052982</value>
     </param>
     <param>
-      <key>start</key>
-      <value>1800e6</value>
+      <key>type</key>
+      <value>eng_float</value>
     </param>
     <param>
-      <key>stop</key>
-      <value>1900e6</value>
-    </param>
-    <param>
-      <key>step</key>
-      <value>2e5</value>
-    </param>
-    <param>
-      <key>widget</key>
-      <value>counter_slider</value>
-    </param>
-    <param>
-      <key>orient</key>
-      <value>Qt.Horizontal</value>
-    </param>
-    <param>
-      <key>min_len</key>
-      <value>100</value>
-    </param>
-    <param>
-      <key>gui_hint</key>
-      <value></value>
+      <key>short_id</key>
+      <value>s</value>
     </param>
     <param>
       <key>alias</key>
@@ -1702,7 +1710,7 @@
     </param>
     <param>
       <key>_coordinate</key>
-      <value>(304, 11)</value>
+      <value>(16, 83)</value>
     </param>
     <param>
       <key>_rotation</key>
@@ -1751,10 +1759,4 @@
     <source_key>C0</source_key>
     <sink_key>bursts</sink_key>
   </connection>
-  <connection>
-    <source_block_id>gsm_receiver_0</source_block_id>
-    <sink_block_id>blocks_message_debug_0</sink_block_id>
-    <source_key>measurements</source_key>
-    <sink_key>print</sink_key>
-  </connection>
 </flow_graph>