More autonomy for blind people thanks to satellite navigation

The “Tormes” system is a computer with a Braille keyboard and satellite navigation technology that gives verbal directions. The hand held device was built by ONCE (the Spanish National Organisation of Blind people) with the Spanish company GMV Sistemas using EGNOS (European Geostationary Navigation Overlay Service). This personal navigator speaks to the user, like any GPS device in a car, weighs less than one kilo and can be used in two ways: to guide the user to their destination or to tell them where they are as they walk around. Where the accuracy given by GPS is not precise enough and not guaranteed, EGNOS corrects the GPS signals and gives an accuracy of 2 m (as compared to 15 to 20 m accuracy given by GPS). It also warns the users of any problems with the signal, thus giving integrity information. EGNOS is transmitted to the ground via geostationary satellites, which results sometimes with signals being blocked by buildings. This is called the canyon effect. To solve this problem, ESA engineers had the idea of getting the data through the Internet via a GSM connection, a project called SISNeT (Signal In Space through Internet), making EGNOS available anywhere downtown. The system is not intended to replace a white cane or a guide dog but rather to complement them with an audible map.