Re: Hydrophone

[hylands@ibm.net (Jon Hylands)]

On Thu, 18 Feb 1999 12:37:39 +1100, Pet Porpoise Pool
<porpoise@midcoast.com.au> wrote:

> Further to this I am currently experimenting with a video transmiter
> attached to a small ccd camera which we are attaching to seals and dolphins
> in captivity with the intention of following and monitoring whale movements
> but are having trouble with the signal reception when the animal is
> underwater.

Won't work at all. Radio waves will not propagate under salt water at all.

There are a number of AUVs (autonomous underwater vehicles) that use
acoustic modems to communicate between the sub and either another sub or a
ship on the surface. Currently, the best data transfer rate I have seen is
19,200 baud.

Needless to say, real-time video is not doable. There's a small body of
research looking into using wavelet compression algorithms to try and get
something that approaches real-time video.

For more information, check out the following URLs:

http://www.nosc.mil/robots/undersea/auss/auss.html
http://www.ensc.sfu.ca/research/url/people/

Later,
Jon

--------------------------------------------------------------
   Jon Hylands      Jon@huv.com      http://www.huv.com/jon

  Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
           http://www.huv.com