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"NIL-VISIBILITY" GUIDANCE SYSTEM A N automatic land-navigation system designed to be
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used under conditions of nil visibility—principally thick fog— has been developed by the Watford company of S. G. Brown Ltd., a member of the Hawker Siddeley group, in association with Aviation Electric Ltd., a member of the Bendix group. This self-contained navigation system was demonstrated last week at London Airport (Heathrow), and it can be fitted to any type of road vehicle, the Arrna-Brown gyro compass around which it is based already being used in military tanks and scout cars. Although not intended for the private motorist, the system could well be of considerable importance to police, fire, ambulance and civil defence services.
The heading direction of the vehicle is determined by the Arma-Brown gyro compass, which is similar to the kind used for marine navigation. The speed of the vehicle is measured by a drive taken from the gearbox in the same way as for a normal speedometer, and the speed and direction are then combined in a miniature computer to give the vehicle's position in terms of standard grid co-ordinates. An illuminated arrow on a map shows the position and direction of the vehicle at all times, whilst a compass heading is also available separately.
The system is completely self-contained and does not depend on any external devices. It is unaffected by magnetic disturbances, electrical fields and so forth, and will work equally well in tunnels or near other vehicles. It is claimed that very high accuracies are obtained, and it is said to be normally possible for the driver to determine which side of the road he is on by reference to the map display alone.