In a mathematical sense, the curvature is the reciprocal of the radius, so that a smaller curvature implies a large radius. A curve of large radius, as for a railway, cannot be laid out by using the radius directly. We will see how the problem of laying out a curve of large radius is solved.
In 1983, Motorola released its first commercial mobile phone, known as the Motorola DynaTAC 8000X. The handset offered 30 minutes of talk-time, six hours standby, and could store 30 phone numbers. It also cost Â£2639 ($3995). In the very early days of the mobile space handsets werenât designed with consumers in mind.
Handsets that could be used in a vehicle had been developed prior to Martin Cooperâs phone, but his was the first usable truly portable mobile telephone. Cooper made mobile phone history in April 1973 when he made the first ever call on a handheld mobile phone. 1  Japan became the first country to have a city-wide commercial cellular mobile phone network in 1979.  The Nordic Mobile Telephone (NMT) system launched in Denmark, Norway, Sweden and Finland in 1981.