Route entry guiding device and method in a navigation system using a portable terminal

A route entry guidance method in a navigation system using a portable terminal, comprising the steps of:

• (1) receiving information including a departure point and a destination from a user;
• (2) transmitting the departure point and destination information to a traffic information center;
• (3) downloading optimum route information processed in a predetermined format from the traffic information center;
• (4) checking whether the optimum route data contains a road corresponding to a present position of a vehicle measured by a navigation sensor;
• and
• (5) guiding the vehicle to an entry to an optimum route if the optimum route data does not include the road corresponding to the present vehicle position.

A method of guiding a vehicle to an entry to an optimum route when a road corresponding to a present position of the vehicle is not contained in optimum route data downloaded from a traffic information service center using a portable terminal, the method comprising the steps of:

• calculating a shortest distance to the optimum route;
• determining a guiding mode according to the shortest distance;
• determining a heading of the vehicle with respect to true north using latitude and longitude coordinates of two points measured by a GPS (Global Positioning System);
• calculating a relative angle of a projection direction to the optimum route with respect to the vehicle and determining a direction to the optimum route according to the calculated relative projection direction angle;
• calculating a relative angle of the direction the optimum route runs with respect to the vehicle and determining a route direction according to the calculated relative route direction angle;
• and
• guiding the vehicle to the entry to the optimum route according to the determined guiding mode, direction to the optimum route, and route direction.