Analysis on Properties of GPS Signals in the Indoor Circumstances

The indoor circumstances include indoor places, forests and city environment and so on. The quality of GPS(Global Positioning System) signals in the indoor circumstances is deteriorated seriously. GPS signals in the indoor circumstances are analyzed in the signal power, the TOA(Time Of Arrival) and the reception S/N, and a simple method by which the degree of signal deterioration can be measured is presented in the paper. Finally, it is concluded that the signal power, the TOA and the reception S/N of GPS signals are worsened severely, and positioning precision of GPS receivers, availability of GPS signals and general performances of GPS are declined in the indoor circumstances, compared with the common circumstances.