A position acquiring apparatus for specifying the spatial position of a mobile station is provided for a mobile communication system composed of a plurality of base stations fixed on the ground and a mobile station moving on the ground or water or in the air, whereby hand-off control can be executed at proper switching timing or diversity reception control requiring short processing time can be carried out. A receiving unit of the mobile station receives signals transmitted from the base stations, and an extracting unit extracts a predetermined synchronizing signal and an identifying signal contained in each transmitted signal. A time difference detecting unit monitors the timing at which each of the predetermined synchronizing signals is extracted by the extracting unit, to detect a time difference between each extraction timing and predetermined timing. A base station coordinates detecting unit detects position coordinate values of each of the base stations, based on the identifying signals. Based on the time differences and the position coordinate values thus obtained, a mobile station coordinates calculating unit calculates position coordinates of the mobile station.

A system and method for positioning control and management of racing sailboat positions and velocities includes the strategic placement of global positioning receivers and transmitters at a buoy and committee boat marking the sail race start line, as well as radio and global positioning receivers on the sailboat. Global positioning system (GPS) and radio transmitter units are mounted on a race start buoy and committee boat and another GPS and radio transceiver unit receives GPS signals from positioning satellites and radio signals from the race start buoy and committee boat. The information received by the racing sailboat is processed to determine relative and absolute positions and velocities, and estimated time of arrival (ETA) at the intercept between current sailboat course and the race start line for display in user-friendly race management.

A position detection apparatus can accurately detect user's own position and other user's position. The position detection apparatus includes a position detecting means (1) for detecting user's own position, a memory means (2) for storing therein map information, a transmitting-receiving means (4) for transmitting user's own identification data and user's own position information from the position detecting means (1) and receiving other user's identification data and other user's position information and a display means (3) supplied with user'own position information from the position detecting means (1), other user's position information from the transmitting-receiving means (4) and the map information from the memory means (2) and displaying a map on which marks indicating user's or other user's position or user's own and other user's positions are put.

A vehicle-equipped navigation apparatus and a navigation communication system which are capable of providing a clear display and preventing own vehicle position information from draining out to third parties. A setting part is provided for setting a remote vehicle either in a valid state or in an invalid state, such that only a remote vehicle position transmitted from a remote vehicle set in the valid state is displayed on a display together with an own vehicle position.

An emergency vehicle alert system includes an emergency vehicle unit, a motor vehicle unit and a plurality of global positioning system (GPS) signals. The emergency vehicle unit includes an emergency GPS receiver, and RF transmitter. The motor vehicle unit includes a vehicle GPS receiver, RF receiver, microcontroller, and warning display. The emergency GPS receiver inputs at least three GPS signals from a plurality of GPS satellites. The emergency GPS receiver transforms the at least three GPS signals into an emergency location signal string. The emergency location signal string is transmitted by the RF transmitter. Each RF receiver which is within range of the emergency vehicle transmission will receive the emergency location signal string. The vehicle GPS receiver inputs at least three different GPS signals from the plurality of GPS satellites. The vehicle GPS receiver transforms the at least three different GPS signals into a vehicle location signal string. The microcontroller compares the location of the emergency vehicle to the location of the motor vehicle and enables at least one indicator lamp.