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Abstract

With the rapid development of smart phones, location-based services based on smart phones are more and more widely used in human production and life. However, due to the accelerated urbanization process, the location scenarios of smart phones are gradually diversified, and smart phones are required to provide high-precision location estimation in a variety of types of scenarios, such as overhead, under the shade of trees, and urban canyons. In the data combination stage after environment awareness, currently, satellite signals are usually combined with other signals. However, in the restricted environment of GNSS such as urban canyon, the satellite signal is easily reflected and attenuated when it is blocked, and because smart phones use low-cost GNSS chips and built-in omnidirectional antennas, the accuracy of the positioning system is significantly reduced. We achieve centimeter-level 1D positioning of acoustic signals at a distance of tens of meters, which to be tightly coupled with GNSS. Based on TDCP (Time-Difference Carrier-Phase), we proposed an optimization algorithm for GNSS integer ambiguity. We use the speed and distance estimates of the acoustic signal to improve the integer ambiguity floating-point solution accuracy, construct the ambiguity search space iteratively through the acoustic signal, thus improving the ambiguity estimation efficiency. Experimental results confirm the superiority of this method in GNSS restricted environment.