Data encoding techniques used in Altera FPGAs

The question is too general for a simple answer, I fear. There's is a 500 pages handbook part about the Stratix IV Gigabit Transceivers, did you get at least an overview what it's talking about?

At the byte and bit coding level, you find some basic elements, e.g. 8B/10B encoding, that are more less common to all fast serial protocols. In so far, most serial data streams look almost similar when watched on an oscilloscope, apart from a varying data rate.

This applies at least to binary data links that don't use modulation. Some interface standards, e.g. several fast Ethernet variants use modulation and need dedicated hardware.

Regards,

Frank