THE funny thing is, advance detection does NOT require B.Detection; it only needs invisible digging and lvl 10 sixth sense. Yea weird but that's how it is
You can actually specify a piece of ground to detection for A.Detection (as shown on the little gif in Jap wiki a few post ago). The size of the detect circle depends on your skill lvl (<lvl 8 has a size of 3x3, lvl 8 and up has a size of 4x4), as is the time of the red circle staying on the ground (lvl 1 is 9 sec, lvl 10 is 27s). Recharge time is always 15 secs. The depth you can detect is based on your skill lvl and your DA. @ lvl 1 you mulitply DA by 3 for the depth; @ lvl 10 the number is 7.5.