"Martin Baxter" wrote in message
...
Dave wrote:
On Mon, 19 Nov 2007 16:48:45 +0100, "Edgar"
said:

Probably got its sense of direction screwed up by all the underwater
sonar noise that submarines etc. are making these days.

"These days" being the last 50 years?

You know that sonar has changed quite a bit over the past 50 years?
However even though transducer power has increased vastly thanks to modern
electronics, the amount that active sonar gets used is also much less,
again thanks to modern electronics and computational abilities. Why send
out a massive ping that can be detected 500 miles away when you can quite
nicely track a target 100 miles away using one ore more of your passive
arrays? Alternatively, again because the listening side of the kit is so
much better than 50 years ago, even if you have to go active, an extremly
low power ping will do, (something that couldn't be done 50 years ago, you
got a big ping, or no ping at all).

Cheers
Marty
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Surface ships encounter a lot of noise to go passive unless they are using a
VDS array such as the
SQS-35. I've had the opportunity to see firsthand what the SQS-26 could do
to marine mammals. The transmitted acoustic power of that sonar was 250,000
watts. It was so powerful you could here the reflection off of the bottom.
We could turn it on and clear the harbor of any submarines.