Radio handset and position location system

A method of position calculation for a radio handset, comprising the steps of storing information of a plurality of radio stations;

• receiving signals transmitted from at least a part of said plurality of radio stations;
• creating delay profiles for said received signals;
• extracting signal reception timings of said received signals from said delay profiles;
• and
• selecting radio stations to be used for position calculation by determining not to use at least one of radio stations having a same PN offset value.

A method for calculating a position of a radio handset in a system comprising a radio handset and a plurality of radio stations, comprising the step of:

• in said radio handset, storing information of a plurality of radio stations, and receiving a plurality of signals transmitted from at least a part of said plurality of radio stations;
• creating a plurality of delay profiles for said plurality of received signals;
• extracting signal reception timings from said plurality of delay profiles:
• selecting radio stations to be used for position calculation by determining not to use at least one of a radio station having a PN offset value same as another radio station included in the information stored in said radio handset:
• and
• calculating the position of said radio handset using said extracted signal reception timings corresponding to said selected radio stations.

A radio handset for position calculation, comprising;

• a storing means for storing information on locations of each of a plurality of radio stations;
• a signal receiver for receiving signals transmitted from at least a part of said plurality of radio stations, each of signals from each of the plurality of radio stations having a PN offset value for a location of each of the plurality of radio stations;
• a delay profile calculator for creating delay profiles for said received signals in accordance with PN offset values included in each of said received signals;
• and
• a CPU for extracting signal receptions timings of said received signals based on said delay profiles,
• wherein, if said CPU selects radio stations to be used for position calculation in accordance with signal reception timings extracted by the CPU by determining signals not to be used having an identical PN offset value, and calculates a location of the radio handset without using PN offset values corresponding to radio stations whose PN offset values are identical.