## 2 Vector Tracking Loop Operation Mechanism  
In a traditional receiver, each tracking channel is independent of the other; each channel completes the tracking of the satellite signal; measures the pseudorange and pseudorange rate of the corresponding satellite; and then obtains the user's position, speed, and receiver clock difference through the navigation solution module. However, because each tracking channel of the receiver completes the tracking and positioning of the same user, there is correlation between the channels, while the traditional receiver, that is, the receiver using the scalar tracking method, ignores the correlation between the channels. In contrast, the vector tracking loop simultaneously processes the signals from all channels to give the navigation solution, and the common processing of all channels can make use of more information hidden in the signals so that the channels can help each other, thus improving the performance in a low carrier-to-noise ratio environment. Vector tracking technology is a very promising emerging receiver technology. Its operating mechanism is shown in Figure 1.  
First, the IF signal is multiplied and correlated with the local carrier and local C/A code, and the high frequency and noise in the signal are filtered through the integral cleaner to improve the carrier-to-noise ratio. The code phase error and carrier frequency error containing noise are extracted by the code phase discriminator and carrier frequency discriminator and input into the navigation filter to obtain the error between the estimated value and the true value of the parameters, such as position and speed. The adaptive SRCKF algorithm is used to obtain the modified values of the estimated values of each parameter at the current time, output the estimated values of each parameter at the next time, obtain the code phase and carrier frequency estimation through geometric projection, and adjust the local code/carrier generator to output the local carrier and pseudocode to enter the next cycle. Figure 1: Vector tracking loop structure block diagram. When the receiver is in a highly dynamic state, its vector tracking loop model will be very different from that of the nonhigh dynamic state. It is assumed that the velocity, acceleration, and jerk vector of the receiver in a highly dynamic state are as follows: \(V=\left[V_{x}\ V_{y}\ V_{z}\right]\), \(V^{\prime}=\left[\ V_{x}\ V^{\prime}\ V_{y}\ V_{z}\right]^{\prime}\), and \(V^{\prime\prime}=\left[V_{x}\ V^{\prime\prime}\ V_{y}\ V_{z}\right]^{\prime}\); then, the process equation is as follows [17]  
\[[\textbf{X}_{k}]^{2}=\left[ \begin{array}{ccc}I_{3}&TI_{3}&\frac{1}{2}T^{2}I_{ 3}\\ \textbf{0}_{3}&I_{3}&TI_{3}\\ \textbf{0}_{3}&\textbf{0}_{3}&I_{3}\end{array} \right]^{2}[X_{k-1}]^{2}+\left[ \begin{array}{cc}\frac{1}{2}T^{2}\textbf{I}_{3}\\ TI_{3}\\ I_{3}\end{array} \right]^{2}[W_{k-1}]^{2} \tag{1}\]  
where \(\textbf{X}_{k}=\left[L_{kx}\ \textbf{L}_{ky}\ \textbf{L}_{kz}\ \textbf{V}_{kx}\ \textbf{V}_{ky}\ \textbf{V}_{kx}\ \textbf{V}^{\prime}_{kx}\ \textbf{V}^{\prime}_{ky}\ \textbf{V}^{\prime}_{kx}\ \right]^{T}\), \(\textbf{W}_{k-1}=\left[V^{\prime}_{kx}\ \textbf{V}^{\prime}_{ky}\ \textbf{V}^{\prime}_{kz}\right]\) is the state disturbance noise.