This data sheet (google search) seems to have a lovely description of the
RC5 basics
-http://users.pandora.be/nenya/electronics/rc5/ and more data
+http://www.nenya.be/beor/electronics/rc5.htm and more data
http://www.ee.washington.edu/circuit_archive/text/ir_decode.txt
and even a reference to how to decode a bi-phase data stream.