Finding the way with satellite navigation

Introduction
There is a great deal of interest in navigation technologies among blind and partially sighted people. For an experienced user this can significantly increase the ability to travel independently.
Global Positioning Systems (GPS) use radio signals from a network of satellites to give the location of a portable receiver. This can then be used to output information such as direction of travel, or to mark 'points of interest' when the unit is in a particular location. It is then possible to get directions to that point of interest from another location.
GPS systems can be accurate to within a few feet, so are useful to pedestrians, but this level of accuracy is not always possible. GPS relies on line of sight to satellites, so the signal becomes weak or can be blocked altogether by trees and tall buildings and is affected by weather conditions.
It is important to remember that this is a navigation aid, not a mobility aid and cannot replace a guide dog or a long cane. GPS products will not provide any warning about obstacles.
A dedicated GPS unit
There is one dedicated speaking GPS unit available. This is the Victor Trekker from Humanware. It is a mainstream PDA controlled by a touch screen, adapted with a tactile overlay and speech output software. This is connected to a GPS receiver and gives navigation information to the user as speech output.
The Trekker provides real-time information detection such as route intersections and points of interest. Users can add their own points of interest. GPS reception and accuracy status can be accessed and verbosity levels changed. Routes can be previewed on or off line and then planned or recorded as they are travelled.
GPS for notetakers
GPS units are available for the BrailleNote and PacMate ranges of notetakers. This BrailleNote GPS provides information about your speed, the direction you are travelling in and your altitude. It can calculate the distance and direction to a street address or intersection and hundreds of points of interest. It can also automatically create routes for either walking or riding in a vehicle.
The GPS add-on for the PacMate is called StreetTalk. The unit can give its location in speech or braille, as an address, or latitude and longitude. StreetTalk has a route-planning mode and can guide the user turn by turn to an address or point of interest.
Earth calling – GPS on talking phones
One way of accessing GPS is to connect a receiver to a mobile phone with speech output. One interesting project is Loadstone. This is a free GPS system for use on Symbian 60 series mobile phones, connected to a Bluetooth GPS system.
It does not include map data like the other available products, but has a facility to mark points of interest. It can recognise a particular mobile phone base station and other functions, including matching latitude and longitude.
Loadstone has a community of users who share points of interest in areas they know and other users can access these when they visit that area. Mutual technological support and knowledge sharing is encouraged via a mailing list. Loadstone can be accessed with Talks or Mobile Speak software.
Another option for mobile phones, is using the mainstream GPS product Wayfinder. This is a subscription service that uses the GPS receiver to establish the unit’s location, and then downloads map data and points of interest to the phone. The software will run on Symbian series 60 phones and is accessible with Talks software. It is a subscription service and there is also a cost for downloading data and searching the directory.
Future developments
It is interesting to speculate on what the future development of GPS devices may involve, such as it being combined with other technologies. Some users have commented on what they hope the future might hold:
David says "A 100 percent accessible mobile phone, with at least 300 GB of storage, MP3 player, GPS receiver and accessible office software all in one gadget!"
Although they don’t have that sort of storage space, some of the products mentioned in this article are close to this as the BrailleNote and the Pacmate are used as laptop replacements. Some mobile phones such as the Nokia Communicator have office software and can interface with PCs.
Vince puts the emphasis firmly on navigation and mobility. "If it could alert me to which bus is coming, where it goes to and where it's stopping, so I can leave home without a crystal ball, so much the better. If I can leave home without a daisy chain of three or four devices to achieve this one thing, also so much the better."
It is easy to imagine a future in which a mobility device could give spoken information routes and timetables triggered by signals from the buses and stops. Some GPS systems already access directory information online. If this could be coupled with other navigation and mobility technology, it could enable blind people to find their way in new places with far more independence than is possible today.
A user’s comments on GPS
Dave recounts his recent experience: "A couple of months ago I got a BrailleNote PK with GPS, and had training on it about two weeks ago. I haven't really got used to using the GPS yet other than the training I had.
It seemed to work well, although a couple of tests we gave it, took us a rather long way round, rather than the direct route. The trainer from Humanware said I was expecting too much of it. Because I knew the route; I was expecting the GPS to choose the same path. Whereas if I had been on unfamiliar ground, I would have been happy that it had got me from one place to another, and wouldn't have known I had gone a long way round.
I sort of understand what he's saying, but seems a bit of a strange way of looking at it."
Dave goes on to tell us more about what he likes about GPS: "What is good on the PK is that you can go into 'virtual' GPS mode, load the appropriate map, name a city and address and then read all the 'points of interest' around that address, such as pubs, restaurants, railway stations, theatres and other street names. Hence, I get a good idea of what is around, how far away it is and in what direction. This mapping and orientation information is a useful resource in its own right, without the guiding facilities.
Obviously I will next need to practice using the GPS unit when I'm out and about to see how it gets on getting me from A to B. Incidentally there is also a vehicle mode for when travelling on public transport or by car."