This brief article describes a device, designed jointly by the Americans and the Japanese, that enables motorists to find their way around with a navigation system that displays colour maps on the dash board. The device shows a cars position to an accuracy of 100 metres on a map stored on a laser disc, and relies on the US Govenments Global Positioning System (GPS). The GPS is a network of satellites in six orbits, each circulating the earth every 12 hours. When the network is complete, 24 satellites will be in place. Each satellite sends out a continuous identifying time signal. To fix its position a receiver needs to be in range of 4 satellites, one to provide a reference signal, the other 3 for directional bearings. Because the satellite orbits are predictable; the receiver can calculate its position from their relative positions at a known time. The receiver then corrects for irregularities in the shape of the earth and displays a location to an accuracy of about 100 metres. At present only 12 satellites are working, providing cover for only 14 hours/day. From 21 June, Japanese motorists will be able to use this network using a decoder which fixes the cars position on a 1:40000 map displayed in colour on a liquid crystal screen. Data for the maps come in 4 optical discs which cover the whole of Japan. Other systems, such as Trafficmaster, and Autoguide are mentioned briefly.

  • Availability:
  • Corporate Authors:

    IPC Magazines Limited

    Holborn Group, King's Reach Tower, Stamford Street
    London SE1 9LS,   England 
  • Authors:
    • Cross, M
  • Publication Date: 1990-5-28


  • English

Media Info

  • Pagination: p. 34
  • Serial:
    • Volume: 126
    • Issue Number: 1718
    • ISSN: 0262-4079

Subject/Index Terms

Filing Info

  • Accession Number: 00606362
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Mar 31 1991 12:00AM