Research On Accuracy Of Pseudo-Ranging Under Complex Channel Environment

PN code ranging method is widely used in the TT & C system, Tracking and Data Relay Satellite System and Global Navigation Satellite System. Compared with the other ranging methods, PN code ranging signal has advantages such as, low power spectral density, small interference on adjacent channel, strong confidentiality, being difficult to be intercepted, applying in CDMA system. In the same way as other ranging methods, PN code ranging is also affected by various error sources. The systematic errors can be eliminated by modeling or data processing method, however, ranging random errors caused by accidental environment factors are difficult to be modeled or eliminated.The accuracy of PN code ranging is codetermined by selected PN code element width and receiver's tracking accuracy. The limitation by symbol width can be solved by adjusting the clock frequency. In addition to hardware limitations, the tracking accuracy is vulnerably affected by external environment interferences.This dissertation first introduces the structure of PN ranging system and basic principles of PN code ranging as well as code tracking loop and carrier tracking loop working in PN code ranging receiver. The usage of the estimation of the carrier phase estimated by carrier tracking loop is being investigated. By making use of the carrier-assisted technology, such that we can obtain the accurate pseudo-code delay estimation. After the analysis of the changes of loop carrier to noise power ratio under RF interference environment, the simulation results of pseudo-range measurement error of are presented. Finally, this dissertation presents careful analysis of the characteristics of the multipath signals, under high and low refraction environment, the pseudo-range errors and carrier-phase tracking errors which introduced by the mutlipath effect are thoroughly investigated, and then the simulation results are presented.