that long. moving on to a look what is actually looking for the black box. you have a surface ship, in this case an australian ship, towing the t.p.l., the towed pinger locator. the depth that it is being towed at, about two miles from two miles underneath the surface, that s how far this thing is underwater, under the surface of the water. and it will sweep back and forth, the surface ship will, in paths that are approximately two miles apart. it is an incredibly slow process and it s so far not yielded an exact fix on where those black boxes might be sitting. with more on the search, let s bring in captain nash, a fox news military analyst. chuck, they have heard something on the frequency that belongs or is assigned to a black box. i believe it s 37.5 killahertz.
is there anything else in the ocean that would make that sound? people have speculated it could have been harmonic from shipping or a pump motor or something where you have the primary frequency and shadow frequencies. i don t think that s the case, though. i think the other day when they got two hours and 20 minutes of good, solid pinger data, and i believe that s what it was, because they re not just listening at 37.5 but they also have spectrum analyzers that look at the wave form and look and they know exactly the frequency exactly what it is. they would not be talking about that as strongly as they are if they thought that it was a whale or some other natural not for two hours and 20 minutes. jon: but here is one of the things that bothers me, and maybe we can put up the map that shows essentially where a couple of different ships have been
requirement is plus or minus one kilohertz. so it can be 37.5, 36.5 to 38.5. chris is right. there are a lot of reasons that you can begin to see a shift in the pinging, the pinging frequency and that s the kind of parameters he s talked about. so this is nothing to be disturbed by, it s just one of the pieces of evidence when you re in the real world and real world equipment it doesn t function quite the way the ideal system does. chris, turning to the chinese ship for one second one reason some were optimistic about this the chinese ship detected pulses at that 37.5 kilohertz frequency. that frequency is not chosen by accident. can you explain why 37.5? well, it s an ultrasonic frequency that s not readily found in nature. the reason for it is you want it to stand out in the band width.
can travel 2 1/2 nautical miles. cliffs and vegetation can get in the way limiting that distance. before any beacon is shipped from here its sound output is measured in one of these huge 50,000 gallon tanks. it s lowered into the tank through the floor above. surround by hydrophones, ultrasonic readings are recorded on this computer. this pinger is twa flight 800 which went off the coast of new york back in 1996. this company made the pinger. after it was recover they got it back. this one was found in shallow water but they are designed to function in water as deep as 20,000 feet. what about the frequency? crews at sea picked up a slightly lower frequency than the pinger s standard frequency of 37.5 kilohertz. water temperature can shift the frequency. it s so distinct, right? there s nothing else that would
it s at a lower transmission frequency than the standard 37.5. a change possibly due to environmental factors. if there s a change in pressure on the ocean floor and the age of the particular batteries, the capacitants can change. reporter: they are guarding against intermission near the ocean shield. 375 miles away, search crews haven t given up hope on the other pinging sounds reported by the chinese. two search areas but so far neither has reacquired the sound they need. australian officials say they will keep searching for that pinging sound until there is absolutely no doubt the pinger batteries have expired.