How to read serial data from the Neurosky chips
http://developer.neurosky.com/docs/lib/exe/fetch.php?media=mindset_communications_protocol.pdf

This is fully documented, the 2 0xAA bytes (170) are the sync bytes at the start of a message, the next byte is the payload length, and finally you have the CRC. 

The linked pdf even has example code for parsing the data,