John Calvin wrote:
>
> <SNIP>
>
> > Then you've also got the sonar nets that girdle the
> >US. Anything that is metallic and is below the surface gets tracked when
> >it comes within a certain range.
> >
>
> Actually Mike, the SOSA system to which you refer is a passive system. It is only able to track things that make noise regardless of the chemical makeup. Active sonar, where being metal really makes a difference is in itself detectable, due to the fact that it must send out the sound signal (ping) and wait for the reflection. Now a magnetic detection system, which SOSA is not, would function as described in your above paragraph.
I suppose most people are not aware of the sophistication of the newer
systems. The newer systems do function passivly, but while they
primarily work off of source transmissions, there are also some
'undocumented features': they also 'image' the 3D space of the ocean off
of ambient diffuse sound, much as whales do. So they can spot any object
of a given minimum sonic cross section. A metallic bouy actually
reflects quite well compared to soft animal flesh, which is the normal
aquatic mammal target. Many whales echolocation capability is sensitive
enough to sonically image an entire ocean off of one or two calls, and
the newest mikes were privately developed specifically for studying
whales, but the tech was seized by the Navy at the patent orifice. So
unless you grow your bouy out of a meat vat, your bouy is gonna stick
out like an 18 wheeler on a Nevada highway patrolmans radar scope...
This archive was generated by hypermail 2b29 : Thu Jul 27 2000 - 14:13:18 MDT