Tracking of time hopped DS-CDMA signals for pseudolite-based positioning

Locata’s positioning technology was designed to be used as analternative to GNSS in classically-difficult GNSS signalenvironments. A network of time-synchronized terrestrial transceivers(LocataLites) forms a positioning network (LocataNet) that canoperate entirely independent of GNSS. Operating in the 2.4GHz ISMlicence-free band, the Pseudolite Positioning System (PPS) is immuneto the near-far problem due to the usage of TH/DS-CDMA signal.Conversely, the use of such signals results in the degradation of codetracking performance in comparison to an equivalent DS-CDMAsystem. The relative performance degradation is proven viatheoretical derivation and simulation to be directly related to the dutyfactor of the TH/DS-CDMA signal. The transient behavior of thesignal is also observed and compared to the conventional DS-CDMAsignal. This type of signal provides an efficient way to track multipletransmitter using only one tracking loop.