Abstract: In the preliminary analysis of the actual positioning error of the BeiDou module, it was found that the distribution of positioning error of the BeiDou module follows a normal distribution. According to the distribution law of positioning error of the BeiDou module, the dual antenna module on the same circuit board receives the BeiDou positioning signal and transmits the positioning information to the TMS320F28335 DSP chip. The DSP performs real-time algorithm processing on the positioning information provided by the BeiDou module and transmits the processed positioning information to the embedded ARM chip. The ARM chip updates the positioning information on the TFT LCD screen and sets the working mode of the BeiDou module according to user requirements. Unable to receive Beidou positioning information

In the preliminary analysis of the actual positioning error of the BeiDou module, it was found that the distribution of positioning error of the BeiDou module follows a normal distribution. According to the distribution pattern of positioning error of the BeiDou module, the dual antenna module on the same circuit board is used to receive the BeiDou positioning signal, and the positioning information is transmitted to the TMS320F28335 DSP chip. The DSP performs real-time algorithm processing on the positioning information provided by the BeiDou module, and transmits the processed positioning information to the embedded ARM chip. The ARM chip updates the positioning information on the TFT LCD screen. REC670 1MRK002814-AB also sets the working mode of the BeiDou module according to user requirements. When the Beidou positioning information is not received, the DSP uses the UKF filtering algorithm to send the predicted positioning information to the ARM chip, which is marked as the predicted information and displayed on the TFT LCD screen.

The BeiDou positioning system is a global positioning system independently developed by China. Currently, the BeiDou positioning system has 16 satellites in orbit. As of December 27, 2012, the official version of China’s BeiDou positioning system space signal interface control document has been released, and the BeiDou positioning and navigation business officially provides passive positioning, navigation, and timing services to the Asia Pacific region. This system can provide positioning services for commonly used transportation vehicles such as cars, passenger planes, and ships, and provide positioning and navigation services for precision guided weapons. It is of great significance for China’s military defense industry to break away from dependence on foreign GPS systems. In addition, it also has important significance for agriculture, animal husbandry, and fishery production.

In the context of numerous practical applications, it is particularly important to improve the positioning accuracy of satellite positioning and navigation systems. This article proposes a concept based on a dual antenna structure, with the aim of improving the positioning accuracy of the Beidou positioning module, and implementing the Beidou positioning system on an embedded ARM+DSP system.

1 System design concept

Among the many applications of satellite positioning systems, REC670 1MRK002814-AB is commonly used to describe the parameters of satellite positioning accuracy, including Distance Root Mean Square (DRMS), Circular Error Probable (CEP), and Spherical Error Probable (SEP). These parameters are widely used in measurement and various positioning systems, and their calculation and accuracy are closely related to the three-dimensional distribution characteristics of positioning errors. The literature proves that in general, the three-dimensional distribution of positioning errors is elliptical, known as the error ellipsoid. Its geometric features mainly include the axis direction, axis length, and axis ratio of the ellipsoid. The axis direction is the direction in which the three main axes of the ellipsoid are located, the axis length is the standard deviation of positioning error in the direction of the ellipsoid axis, and the axis ratio is the ratio between the three axis lengths of the ellipsoid. The axis ratio of the error ellipsoid determines the probability of the true position falling on the DRMS circle.

After analyzing the literature, a single point 100 sets of continuous Beidou module positioning tests were conducted, and the distribution of errors was statistically analyzed. After actual testing, it was found that the actual positioning error of the Beidou module approximately follows a normal distribution. The horizontal positioning error of the Beidou module converges between 8-10 meters with a probability of 91%, with a probability of 82% at 9 meters, as shown in Figure 1.