mm43: Back in one of the earlier
AF447 threads,
auv-ee explained in detail the detection range of the 37.5kHz ULB pinger. The maximum detection range is 2 - 3km, and in rather calm sea conditions. Less than 1800 meters will provide a 90% or better chance of detection. All this is described in detail by one who knows and has the experience to go with it.
That's assuming the people listening for it have the proper or properly tuned equipment! BTW: Thanks for the link. He definetly explains the transmission end of it. I'm just not sure all the people listening for the 37.5 khz ping of MH370's black box locator beacon, have the optimum equipment to hear it anywhere near the maximum specified distance!