Resonance to find MH370's black box?

[wrtner]

The pinger has only a week or so to run. The matter is urgent.


The "Towed Pinger Locator" appears to listen only for the ping emitted by the Underwater Locator Beacon, ULB, at a frequency of 37.5khz. That's all. It has to be within a mile or so of the crash site to have any hope, given the depths involved in this part of the ocean.

Supposing this device, or an additional device as well, were to emit a signal which sweeps from, say, 32khzs to around 42khz, and listen out for any return signals, we would expect a typical resonance curve, and the response might be more detectable. The detection task would be looking for a maximum or a minimum

Would this approach be more sensitive to the low signal strength than the current method?
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[ElectricMick]

we would expect a typical resonance curve

I like your weirdo threads, wrtner. Todays' response is that it depends on whether the extra hydro-speaker was the other side from the black box or not.It needs trying out in a swimming pool. The null idea is neat - bit like the wheatstone bridge.

Tomorrows' approach is that these gismos need a transmitter that sleeps. When the ship passes nearby, it sends out a ping (some would call it a pulse) and, like Rip van winkle, the device awakens. Battery life would be ten fold or more, although the sleeping device would use a bit of juice.

If these geezers cannot think of this for themselves, then it makes me anxious about their fly-by-wire creations.

[indio007]

Uhh don't US subs broadcast at 37.5 Khz?

[mscoffman]

Hi, I had a similar idea that I came up with during the loss of Air France
flight 447. I really think it is a good one. You know the hundereds of
people lost on these planes would almost all be carrying several
electronic devices. Almost all of these devices including wrist watches
carry an minature operating transmitter called a crystal oscillator
operating at 32.768KHz RF ULF very low power. These are extremely
frequency stable. What I would propose is to look down at the seafloor
from a radio satellite platform using a synthetic aperture radio antenna
tuned to 32.768Khz looking for the RF carrier frequency.

You will object and say these will be destroyed by water depth pressure and salt water.
Yes most would, but the point is that opportunistically some might survive. Some would
survive in luggage, some would survive potted in electrical potting compound, some would
survive in pressure proof containers, some would be in metal containers that are crushed
and sealed. The blackboxes probably have some, other equipment in the aircraft would have
some too.

These will continue long after the ultrasonic pinger has given up.

[wrtner]

When the ship passes nearby, it sends out a ping (some would call it a pulse) and, like Rip van winkle, the device awakens.

Congrats, Mick, you have invented the transponder.
These avionocrats are not as clever as we imagine.
This problem must have come up before.

[ElectricMick]

Congrats, Mick, you have invented the transponder.
These avionocrats are not as clever as we imagine.
This problem must have come up before.

Interesting, wrtner. Point taken. Well done me.

Do you remember that Air France flight that left Brazil and headed over the Atlantic? It is thought to have broken up due to bad weather and poor piloting skills. It took a year or two to find sunken wreckage. The battery is tiny. Why did these alleged deadbeats not put in place something better then? What has to happen to get them to require a 5 year life with a passive transponder design. Maybe with a joule thief to make it last even longer.