Near-far effect mitigation method using pseudolite signal acquisition

In this paper,a new idea based on pseudolite signal acquisition method aiming to mitigate the near-far effect problemin the satellite positioning is proposed.After analyzing the signal capture principle based on coherent integration and non-coherentaccumulation,the cross-correlation interference of strong and weak signals is eliminated by means of normalization of reconstructedstrong signal and judgement of the characteristics of the peak value,which can avoid the near-far effect of the pseudolitesignal.It can also estimate all the strong signals without any additional hardware.By building an indoor pseudolite positioningsystem,the capture performance becomes better based on improved acquisition algorithm compared with that based on thenon-coherent accumulation after coherent integration algorithm.The near-far effect is restrained effectively and the probabilityof weak signal detection is increased by25%.

Effects of Pseudolite Positioning on DOP in LAAS

In this paper, effects on DOP (Dilution of Precision) due to augmentation of Global Positioning System (GPS) with pseudolites are investigated. For this purpose, a typical Local Area Augmentation System (LAAS) scenario is consi-dered by placing pseudolites in various positions. It is found that only properly located pseudolites can improve the DOP. DOP values with two pseudolites located on either side of the run way are found to be the best. Geometric DOP (max) was found to be nearly 4 due to only GPS and came down to approximately 2 due to augmentation with two pseudolites. Implementation aspects of Bayes and Kalman filters while estimating DOP values are also examined.

Simulation on C/A codes and analysis of GPS/pseudolite signals acquisition

The global positioning system(GPS) is an extremely mature technique in the navigation and position-ing field.However,there are still some limits in some aspects and for some special applications.Spe-cially,the performance of GPS needs to be improved with technological advances.As a GPS-like ground transmitter,the pseudolite provides a new research direction to achieve high positioning ac-curacy and reliability.In this paper,we describe the core technologies of designing and simulation on the coarse acquisition codes in constructing the pseudolite system.In the GPS/pseudolite integration system,the signal PRN 36 of the pseudolite and the GPS satellites signals are acquired in the modified receiver based on the computer software platform.It is shown that the pseudolite technology is ideally suited to augment the GPS alone and provide greater integrity,availability,and continuity of the navi-gation positioning system,especially for indoor use.

Research on positioning enhancement scheme of CAPS via UWB pseudolite

The positioning precision of the transmitting Chinese Area Positioning System(CAPS) is reduced due to the non-ideal distribution of the satellite constellation.Positioning and navigation enhancement methods are able to improve the reliability and accuracy of the positioning system,especially for users in special regions and special applications.In this paper,a positioning enhanced scheme based on ultra-wide band(UWB) pseudolite is proposed for CAPS.It is demonstrated that the link budget of UWB pseudolite satisfies the FCC's emission mask requirements.The localization algorithm of the enhanced CAPS is presented.The simulations indicate that the positioning precision of the proposed enhanced scheme is improved greatly,and the feasibility of the enhanced scheme is thus proved.

Design of the pulse duty cycle of the pseudolite signal in local area augmentation systems

The short-pulse TDMA signal is an excellent solution to the near-far problem in the pseudolite augmentation systems,and the pulse duty cycle is an important element in the solution.This paper aims at designing the duty cycle of the pseudolite pulse signals with a theoretical method.At first,the scope of the duty cycle is derived theoretically with the object of ensuring the reception of both the pseudolite signals and the satellite signals,and the expression for the theoretical upper limit is given.Then based on the proposed expression,the duty cycles of Galileo pseudolite pulse signals are designed.The theoretical upper limit can guide the design of the short-pulse TDMA pseudolite signals.

Data Fusion in Distributed Multi-sensor System

This paper presents a data fusion method in distributed multi-sensor system including GPS and INS sensors’ data processing. First, a residual χ 2 \|test strategy with the corresponding algorithm is designed. Then a coefficient matrices calculation method of the information sharing principle is derived. Finally, the federated Kalman filter is used to combine these independent, parallel, real\|time data. A pseudolite (PL) simulation example is given.

An infant monitoring system with the support of accurate real-time indoor positioning

This article presents an indoor infant monitoring system based on Android system which employs a low-cost Bluetooth Low Energy(BLE)pseudolite to accurately locate the infants in the activity indoors and timely remind the parents.It can achieve a positioning accuracy better than 2 m and effectively reduce the risk of injury to infants and young children.The performance of the proposed system,using false negative rate,false alarm rate,and alarm response time as indicators,is compared with that of the system using Quuppa as a positioning source.The experiment results show that both BLE pseudolite and Quuppa as a positioning source can basically meet the positioning accuracy for the infant monitoring system,but the BLE-pseudolite-based system provides a more cost-efficient solution.