Finding lost sub

[hampboats]

Has anyone ever tried using one of the aircraft tracking device to find a lost sub.? They are very small and inexpensive.

-Loud > 85 > dB alarm gets your attention.
-Two alarm tones pattern
-Compatible with AM/FM PPM or FM/PCM RC systems.
-Can be plugged into any standard servo channel.
-Small dimensions and weigh
-Size : 17 X 13 X 10mm
-Weight : 5g
-Operating Voltage(v) : 4-6v
-Current Drain(mA) : 1-35
-Package Weight : ~30g
* Low Battery Alarm when flight pack voltage levels are low, to identify an impending power failure

* Lost Airplane Finder as a tracking device, when searching for a model that has crashed

* Transmitter Inactivity Signal for if the respective Tx stick hasn’t been moved for over one minute, warning that either the transmitter is not turned on, or the receiver has not been turned off, or perhaps some other signal problem exists

Ebay $3.99 plus $3.50 shipping




A listing device can be built that could be lowered into the water. Here is a PDF file with instructions for building one for under $40

www.dosits.org/teacher/activity/hydroph ... _image.pdf
Are there any downsides to doing this as another failsafe or recovery option?

[petn7]

Well if you used it,

Well if you used it, you would need some way to triangulate the subs position which would probably require 3 hydrophones and a computer, right?

I've though this would be the best way to find a lost sub, but it seems pretty expensive and not something everyone can do or afford.

[raalst]

standalone watertight pingers have been

standalone watertight pingers have been developed by a gentleman in the UK. Cannot find the URL right now. (Andy ? can you help ?)

as for triangulation, that is one way.

another is to simulate normal stereo sound. just put the left and right mic into the water at about 5 times the distance between your ears
since in water sound is 5 timeas as fast as in air.
With such a setup an operator can hear where the sound is coming from.
humans can determine the direction of sound with a resolution of about 7 degrees.

I recently found another way : a way to implement an max. 8 channel
microphone array with minimal processing requirements (no adc's)
which could also determine the direction the sound is
coming from.

I aim to add it to a sub I'm building which is fitted with telemetry.

such subs (driving with antenna above water and a laptop on shore to
make an image from the sound data) can readily be used to
locate the lost sub as long as it makes a noise. That is where the pinger
comes in to play again.
of course, such a device can also be built into a sub hunter or other
surface r/c vessel, where telemetry contact is guaranteed.

it will take a while longer to develop this thingy, though.

btw, there are a few other links about hydrophones with piezo elements
http://blog.furibond.com/2007/04/18/...ap-hydrophone/.
Personally, I found the electret ones more sensitive.

this is a picture of me saying hello a lot and walking up and down in front
of a microphone. time scrolls down in this picture. in this case the picture was not made realtime but calculated later using simulation software (Octave/Matlab).

http://www.modelbouwforum.nl/forums/duikboten/75421-sonar.html

[redboat219]

How about using a tethered

How about using a tethered bouy to mark where the sub is. You can either use a timer or command from your transmitter to release the bouy.