Study Of Multipaths Mitigation Method In China Area Positioning System (CAPS) Receiver

CAPS which has independent intellectual property rights is a new generation of satellite navigation and positioning system. In CAPS mode, navigation signal is transmitted by communication satellites, and receiver position is determinated by measuring the time delay from satellites to the receiver. Multipath measurement error of receiver is one of the main source of CAPS positioning error. In this paper, CAPS multipath error is studied and a multipath mitigation CAPS receiver is proposed.Multipath effect makes the phase, the amplitude and the signal delay change. Because the receiver can not distinguish direct and reflected signals, the signals deviate in the estimate of time detection. Multipath effect disturbs the signal modulation and the code correlation, makes carrier phase distortion, reduces the positioning accuracy. At home and abroad, many people study the multipath mitigation method mainly from the hardware design and signal processing technology. From the hardware design of multipath mitigation, including improving the antenna and improving the carrier tracking loop and the delay PLL of the receiver. Multipath mitigation is the signal processing that suppress errors that caused by multipath in the time detection stage.In this paper, the main research work is designing the multipath mitigation CAPS receiver from the antenna, the loop, signal processing. The multipath transmission environment is simulated by the signal generator and cables. Then, we have a group of multipath signals close to the actual situation. Take advantage of the multipath signals that the parameters can be controlled, the chokes antenna is designed. The MATLAB simulation tools are used in the analysis of the performance of the code loop and carrier loop of the receiver under different multipath environment. On this basis, the receiver loop multipath mitigation technology is got. From the perspective of signal processing of multipath mitigation, multipath channel is adaptive estimated, the adaptive channel equalizer is dsigned, so the effects of multipath is inhibited in the receiver. To sum up, inhibiting multipath from the antenna, the loop, signal processing, and other aspects can effectively reduce multipath error and improve the accuracy of the positioning receiver.