What different types of digital video signal do exist?

My major is computer science. Iam working on a project that deals with
analog and digital video signals. I understood that NTSC, PAL and SECAM
are analog broadcast standards. Does it necessarily mean that the above
mentioned three are three types of analog signals. If that is true
ATSC, DVB-T, ISDB-T should be the digital broadcast standards or the
types of digital video signals.
My concern is regarding TTL, CMOS, Firewire, DV. What are
these? Are they different types of digital video signals? If not what
relation does each of those hold with a digital video signal? these
questions have been bugging me. Please do help.
Thanks in advance.