EPIRB Scuba Devices? Why not?

Stories like this one remind
me why I want lots and lots of ways to attract a boat’s attention. I’ve always wondered why no one has made an
EPIRB type device for scuba divers. Obviously, they
couldn’t be water activated (as most are on boats) but I’d happily strap one to the back of tank on each dive in case I
got left behind. Seems obvious to me. Two problems – (1) You need an FCC license and (2) None seem to be enclosed in
cases capable of being at depth. If anyone knows of one that is waterproof at depth, please let me know.