From: utzoo!decvax!harpo!floyd!cmcl2!philabs!sdcsvax!sdccsu3!sdcattb!sdcsla!warner
Newsgroups: net.general
Title: sightless navigation
Article-I.D.: sdcsla.143
Posted: Wed Oct  6 22:29:54 1982
Received: Fri Oct  8 08:52:20 1982

	Discussion of the blind navigation system with some professors,
who are leaders in the field of Cognitive Engineering and who shall
remain nameless to protect them from the sniper mentalities that expose
themselves at the first opportunity, has revealed some new perspectives.

	First; there probably is no way to make the kind of transmitter
I first had in mind, in the relatively limited quantity needed, cheap
enough.  My original conception appears even less cost effective
considering this system would serve a limited population. There are
only two blind ambulatory students on campus here.

	Second; it was suggested that some sort of cheap passive
element be incorporated in lew of the expensive transmitter.  The only
active element of the system would be carried by the blind person. Now
I know that there are range finder devices that are used by blind
people but these devices give no sense of location in the environment
as would a group of (soon) familiar sounds. Question are these devices
ultra-sound like the ones used on cameras?

	It was suggested that the passive device be a radio frequency
resonator. I was told that there are anti-shoplifter devices that use
passive (RF?) resonators.  Do such systems exist? Could this be
modified some how so that several different frequencies would be
involved? Then the transmitter carried by the blind person would
transmit and/or receive on several frequencies and detect various
combinations of the passive elements. The space spanned would be the
similar to the space spanned by transmitters with the unique auditory
sound provided by a heterodyne active unit. I'm talking way over my head
here. Does any one out there know how these detection systems work.  Or
if such systems even exist? I know that there are systems that use
magnetic chips but they are of limited range and are generally not fool
proof. I also don't see how they could be used to generate different
sounds.

	Several persons have suggested infra-red beacons with more
elaborate coded messages, perhaps specific, digitally coded
voice messages, like "beacon three" or "central library" but while this
is a good idea it suffers from the same cost effectiveness problems as 
the transmitter idea.

	Also this deviates from the simple idea of an augmented
aural space which doesn't have to be precisely constructed. Relying
on the adaptive capacity of the sightless person to give semantic
structure to abstract sensory information. 

	The beacon and map idea is nice, but in fact there is an
implied map in the system already. In the same way we know where
we are by looking at the environment so would the blind person know
by listening to the environment. Though the environment must be rich
enough.

	The use of audible signals is also not workable in that they
can be masked by other sounds in the environment and they invade
sighted peoples environment with unnecessary noise.

	Another thing that I have omitted is talking to the two
blind students to see what they think. Could be that they will
just laugh at the idea. I intend to discuss the validity of my idea
with them soon.

	Never the less I would like to test the idea in a mockup 
situation using acoustic sources and blindfolds. Time and money!

	I appreciate all the input so far even the bazaar.

	Ken