Fixed some more docs

README.md

@@ -318,7 +318,7 @@ It can decimate by a floating point ratio.
 
 It uses Lagrance interpolation, where `num_poly_points` (12 by default) input samples are taken into consideration while calculating one output sample. 
 
-It can use an additional FIR filter before applying the Lagrange interpolation. This filter can be activated by:
+It can filter the signal with an anti-aliasing FIR filter before applying the Lagrange interpolation. This filter is inactive by default, but can be activated by:
 
 * passing only the `transition_bw`, or both the `transition_bw` and the `window` parameters of the filter,
 * using the `--prefilter` switch after `num_poly_points` to switch this filter on with the default parameters.

grc_tests/test_fractional_decimator.grc

@@ -155,6 +155,60 @@
       <value>wx.SL_HORIZONTAL</value>
     </param>
   </block>
+  <block>
+    <key>variable</key>
+    <param>
+      <key>comment</key>
+      <value></value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(480, 11)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+    <param>
+      <key>id</key>
+      <value>num_poly_points</value>
+    </param>
+    <param>
+      <key>value</key>
+      <value>20</value>
+    </param>
+  </block>
+  <block>
+    <key>variable</key>
+    <param>
+      <key>comment</key>
+      <value></value>
+    </param>
+    <param>
+      <key>_enabled</key>
+      <value>True</value>
+    </param>
+    <param>
+      <key>_coordinate</key>
+      <value>(608, 11)</value>
+    </param>
+    <param>
+      <key>_rotation</key>
+      <value>0</value>
+    </param>
+    <param>
+      <key>id</key>
+      <value>prefilter</value>
+    </param>
+    <param>
+      <key>value</key>
+      <value>False</value>
+    </param>
+  </block>
   <block>
     <key>variable</key>
     <param>
@@ -386,7 +440,7 @@
     </param>
     <param>
       <key>commandline</key>
-      <value>"csdr fractional_decimator_ff "+str(decimation)+" 20"</value>
+      <value>"csdr fractional_decimator_ff "+str(decimation)+" "+str(num_poly_points)+("" if not prefilter else " --prefilter")</value>
     </param>
     <param>
       <key>comment</key>
@@ -449,7 +503,7 @@
     </param>
     <param>
       <key>_coordinate</key>
-      <value>(840, 379)</value>
+      <value>(784, 379)</value>
     </param>
     <param>
       <key>_rotation</key>