Accessible Global Positioning Systems (GPS)

Today most people have heard of GPS or Global Positioning Systems. GPS receivers are being used by both sighted and blind or visually impaired people to travel more easily. This page provides some basic facts about GPS, how the technology can assist a person who is blind or visually impaired, and accessible GPS product information.

Basic Facts About GPS

Most people that have heard about GPS, really are talking about the receiver. This section summarizes some basic information about GPS.

Brief History of GPS

The U.S. military developed and implemented the global position system for the purpose of national security. In the 1980s, the government made the system available for civilian use. However, the system was intentionally degraded, and accuracy was compromised.

On March 29, 1996, President Clinton issued a Presidential Decision Directive (PDD) that changed the categorization of GPS into an international information utility. The Presidential directive included the following relevant points:

• The U.S. government will continue to operate, maintain and provide basic GPS signals worldwide, free of direct user fees.
• The U.S. will advocate the acceptance of GPS and it's augmentations as a standard for use by initiating international discussions in agreement with Japan and Europe.

What is GPS?

GPS stands for Global Positioning System. It can tell people where they are anywhere in the world. The GPS is made up of three parts:

• satellites orbiting the Earth;
• control and monitoring stations on Earth; and
• the GPS receivers.

GPS satellites broadcast signals from space. These are picked up and identified by GPS receivers. Each GPS receiver provides latitude, longitude, altitude and time.

In general, GPS receivers are composed of an antenna, tuned to the frequencies transmitted by the satellites, receiver-processors, and clock. They may also include a display for providing location and speed information to the user. A receiver is often described by its number of channels: This signifies how many satellites it can monitor simultaneously. The more positional signals a GPS receives, the more accurate it is.

Mapping Software

Some GPS receivers, due to mapping software can provide information about specific locations. These are usually called  POIs or Points of interest.  POIs can include restaurants, hospitals, malls, hotels, banks, and other places.  They also can include single street addresses, road intersections, cities, and waypoint locations. The detail of such information depends on the software that is part of the receiver.  A person buying a GPS unit to investigate what type of mapping software is available, the ease of updating such information periodically, and if a computer is required to update the information.

How GPS Can Assist People who are Blind or Visually Impaired

If you are blind or visually impaired, a GPS product can assist in traveling more independently. But don't get rid of your cane or let your guide dog retire.

An accessible GPS product is a receiver of global positioning information that will let you know where you are in relationship to your environment.  Software generally includes maps of roads and some products also include points of interests. The points of interests may not just be places you want to visit but also serve as orientation.

You should be able to find your way from point A to point B using the information provided by the accessible GPS products. There are several to choose from.  Check the various types to see what bests serves your needs.  

Accessible GPS Products for People who are Blind or Visually Impaired

Common Accessible GPS Products:

• Trekker by HumanWare  - system that uses GPS and digital maps to help blind persons find their way in urban and rural areas