To Whom It May Concern. Black Box 37.5 khz Pings Are Ultra-sonic!
I wrote about this earlier in the forum, but now that it seems there's a good chance there's a legitimate search area, I want to reiterate that submarines and P-3's are set up for listening for submarines, ships, explosions, Say Again Machines, etc, but not optimized for the ultra-sonic 37.5 khz audible ping sent by black boxes. Maybe there are some submariners or P-3 crew that can comment about this. I've read somewhere that an 8 khz ping, would be optimum for typical submarine or P-3 equipment to hear. I know it's redundant to call a 37.5khz ping "ultra-sonic" but I want to emphasize that point. You can't hear it without a dog or down converter. If the equipment has the range, you can look at it on a spectrum analyzer. Just like radio equipment is more sensitive when tuned to a specific RF frequency, listening equipment is much more sensitive when tuned for a specific audio frequency, instead of listening to a broad range of frequencies. This may have been why AF447's ping wasn't heard or not heard consistently enough.