Specifically, remote signs allow people to directly know not only what, but where. Just as sighted persons visually scan the environment to acquire both label and direction information, remote signs directly orient the person to the labeled goal and constantly update the person as to his progress to that goal. That is, unlike Braille, raised letters, or voice signs which passively label some location or give mobility instructions to some goal, the remote signage technology developed at our institute provides a repeating, directionally selective voice message which originates at the sign and is transmitted to a hand-held receiver. The direction selectivity is a characteristic of the infrared message beam and ensures that the person using the device gets constant feedback about his relative location to the goal as he moves towards it. Mainly, signs provide identification.
Street signs can serve as a simple and revealing example of how signs are used.
They know by listening to traffic patterns whether or not the intersection is controlled by a traffic signal. Where intersections involve three or more streets, the listener can at least determine that it is a complex intersection. By noting the direction of signal-controlled traffic, the times when it is permissible to cross can usually be determined. The blind traveler may not notice the pushbutton if there is one. Like the print-handicapped, the blind traveler may not know the name of the street he is crossing.