warner (10/07/82)
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
ehwest (10/07/82)
Infrared transmitters could be placed in trees or lightposts and could easily transmit say CVSD encoded speech over and over again to announce where you are, etc. Such a terminal would cost less than $500 if the speech message could be kept to less than 15 seconds. Power requirements would be less than a watt. Receivers could also be made cheap because of the simple (3 ics) techniques available to amplify the signal and decode CVSD speech. ( See my article in Oct issue on CVSD). Electronics Design Magazine. But, who would pay for it all? Earle West BTL (201) 561-7100
ehwest (10/08/82)
It seems to me that passive RF or magnetic devices like those used for inventory control, in libraries, and on some personal identification badges suffer from an important proximity requirement. A significant amount of energy must be coupled into them in order to work at all, which means they must be either very close to the sensor (inches) or surrounded by a loop sensor like in stores. To work well, a person must be able to identify where he is at a distance of at least 5 feet and probably much more in wide open areas. I have thought about the IR -digital transmitter idea a little more and now I think a transmitter could be built with 2 ics for about $25. It would be very much like a remote control TV transmitter but with an EPROM to store the message which would be constantly dumped. A 64K EPROM could store up to 8 full seconds of speech-- enough to fully identify where you are, which direction you're facing and how to get where youre going. Transmitters could be installed in elevators, hallways, outdoors, or at traffic intersections-- of course at government expense. Receivers would cost a little more. They would be like pocket pagers. 3 or 4 ics and would cost $50 to $100. Centralized EPROM recording machines would be required to record the message into the transmitters memory. Of course someone would have to pay for all of this, but someone already pays for handicapped parking spaces, ramps, special elevators, etc. Why should blind people have to pay for it themselves?