From:	Marc Renouf <renouf@********.COM>
Subject:	Re: Ultrasound vision
Date:	Wed, 3 Feb 1999 14:06:06 -0500

On Wed, 3 Feb 1999, Adam Getchell wrote:

> Moving along to technology that will be present, and should be present in
> Shadowrun, we have interesting research conducted jointly by Scripp's
> Oceanographic Institute (aka UC San Diego) and the U.S. Navy on "acoustic
> daylight".

The "acoustic daylight" stuff is cool, but represents a pretty
serious computational burden. First off, you're looking at sound over a
variety of frequencies, some of which attenuate quickly, some of which do
not. The other problem you have is binocular localization. You need an
array of sensors to be able to determine directionality of the background
noise. Tiny microphones are all well and good, but there are problems
giving them enough directional focus to be able to accurately determine
direction (especially at distance). Granted, packing a lot of them
together helps, but you still have problems.

> Arrays with 1,000,000 or more sensing elements have been able to
> distinguish surface texture between smooth spheres and rough ones at some
> tens of meters. These research also explains the heretofore mysterious
> ability of dolphins and whales to discern incredibly small details using
> their sonar.

Passively? How long is the integration time? It's got to be more
or less outrageous. In SR terms, you don't want to wait 20 minutes before
you can distinguish "friend" blobs from "foe" blobs, especially not
when
you consider that the doppler shift associated with moving targets will
play hell with your resolution.
Personally, I'd like to see more work done on synthetic aperture
sonar, but the applications at present are limited enough that no one's
really interested in it.

> Such a system would be completely passive, yet generate all the benefits of
> Shadowrun "ultrasound" sight with additional bonuses (as the sensor has a
> wide field of view in contrast to Ultrasound's narrow cone).

Ultrasound doesn't need to be a narrow cone, especially if you
have more than one emitter/receiver. In fact, I allow ultrasound goggles
in my campaign (although they are still active sensors). I've even
allowed ultrasound-imaging cyberware (although both the emitters and
receivers had to be installed so that the user could "carry around" their
own ultrasound illumination source). It had power-supply requirements
similar to an eye-laser system, allowing X amount of continuous usage
before the batteries needed to be changed). It was expensive and had
certain limitations, but it had its uses.

Marc