nautical miles. a lot of things can impact that. the thermal degradation, the changes of temperature at the various layers of the water, the sea floor, ocean topology, mountains, cliffs, underwater valleys, vegetation in the water, debris, all of that can degrade the distance at which the signal is heard, and then also as we talked about, the battery output. as we approach the end of life, that signal is going to become weaker and you're going to have to be closer to it to hear it. >> it might become weaker, but would it be intermittent because we're hearing from the chinese news agency it was about a minute and a half in which the signal was picked up. what would be the best explanation in your view if this, indeed, is the pulse of a black box? >> typically the signal is not intermittent. maybe it's weaker and it's harder to hear, but as the battery degrades, the signal would decline in output but you would not get an intermitten si in the operation of the unit.