How to make sense of the signal trace of differential signal
This bus is Manchester encoded.  This means that one symbol (bit) is encoded as a low transitioning to a high, or a high transitioning to a low.  These correspond to 0 and 1 respectively.  Therefore, if you want to send:
 1 0 0 1 0 1 1 1
the sequence is:
HLLHLHHLLHHLHLHL

This encoding moves the center frequency up to the bit rate, eliminating the low frequency content, and makes clock recovery easier.