I'm trying to find out what kind of ANT+ chip is in the xperia active to figure out the specifications (what is supported? background channel search).
Can you help me?
You should be requesting the capabilities using the ANT Capabilities message detailed in the ANT Message Protocol doc.
Not only will your application run on any device with an ANT part providing the required functionality, but you will support the fact that capabilities are dynamic with firmware updates provided by the manufacturers.