Patent ID: 8174439

Claim:
A position information providing system capable of providing position information by use of a first positioning signal which is a spread spectrum signal from each of a plurality of satellites, comprising an indoor transmitter, and a position information providing apparatus, wherein: the indoor transmitter includes a first storage unit which stores therein position data for identifying an installation location of the indoor transmitter, a generation unit for generating, as a spread spectrum signal, an second positioning signal which is a modulated signal having the position data, and a transmitting unit for transmitting the generated spread spectrum signal; and the position information providing apparatus includes a receiving unit for receiving a spread spectrum signal, a second storage unit which stores therein a plurality of code patterns related to the first and second positioning signals, an identifying unit for identifying one of the code patterns which corresponds to the spread spectrum signal received by the receiving unit, a determining unit for, based on a signal obtained by demodulating the received spread spectrum signal using the code pattern identified by the identifying unit, determining which of the first and second positioning signals is received, a position information-deriving unit for deriving position information of the position information providing apparatus, while switching between processing modes depending on a result of the determination, and an output unit for outputting the position information derived by the position information-deriving unit, and wherein: the position data includes first data capable of identifying the indoor transmitter, and second data indicative of the installation location of the indoor transmitter; and the generation unit is operable to generate, as the second positioning signal, a first phase signal having the first data after being subjected to modulation, and a second phase signal having the second data after being subjected to modulation; wherein a clock of the indoor transmitter is independent from a clock of each of the satellites, and the position information-deriving unit is operable, (a) when the second positioning signal transmitted by the indoor transmitter which is one of a plurality of indoor transmitters, is received, to acquire the position data from the signal obtained by the demodulation, and, (b) when a plurality of the first positioning signals are received, to calculate the position information based on respective spread spectrum signals of the plurality of received first positioning signals, wherein the operations (a) and (b) above are switched independently by determining PRN-IDs of the first and second positioning signals.