Update ibadatfile.py

Added the tbased method to get the sampling rate for each channel. This will help to interpolate between points in case someone has different sampling time in each channel.

ibadatfile/ibadatfile.py

@@ -62,6 +62,11 @@ def pda_type(self) -> str:
         """Return the channel unit."""
         return self.channel.QueryInfoByName("$PDA_Typ")
 
+
+    def tbased(self):
+        """Return the channel sampling rate for each channel."""
+        return float(self.channel.QueryInfoByName("$PDA_Tbase"))
+
     def data(self) -> np.array:
         """Return the channel data."""
         if self.channel.IsDefaultTimebased():