## 3 Materials and Methods
### Proposed Deception Velocity-Based (DVB) Discrimination Method  
In order to solve the above problem of the cumbersome process and high computation, a deception velocity-based (DVB) discrimination method is proposed in the subsection. When both receivers are located on the same baseline, scenarios within the radar system can be simplified through a coordinate system transformation. As shown in Figure 2, the multistatic plane is defined as the plane that is determined by the common baseline of the receivers and the target. The right-handed Cartesian coordinate is established in the multistatic plane with the origin and the x-axis unchanged. In the new coordinate system, the physical target's velocity vector can be written as \(\mathbf{v}_{PT}^{\prime}=[v_{x}^{\prime},v_{y}^{\prime},v_{z}^{\prime}]^{T}\). The angle of the PT with respect to the receiver \(\mathrm{R}_{n}\) is denoted by \(\theta_{n}\) in the transformed coordinate system, which can be obtained by the geometrical relationship  
\[ \begin{cases}\cos\theta_{n}=\cos\alpha_{n}\cos\beta_{n}\\ \theta_{n}=\arccos(\cos\alpha_{n}\cos\beta_{n})\end{cases}  \tag{17}\]  
Considering the fact that the velocity component \(v_{z}^{\prime}\) in the \(z^{\prime}\)-axis makes no contributions to the radial speed \(v_{n}\). The relationship between the radial velocity and the velocity vector can be rewritten as  
\[\left[ \begin{array}{c}v_{0}\\ v_{1}\\ v_{2}\end{array} \right]=-\frac{1}{2}\left[ \begin{array}{cc}2\cos\theta_{0}&2 \sin\theta_{0}\\ \cos\theta_{0}+\cos\theta_{1}&\sin\theta_{0}+\sin\theta_{1}\\ \cos\theta_{0}+\cos\theta_{2}&\sin\theta_{0}+\sin\theta_{2}\end{array} \right] \left[ \begin{array}{c}v_{x}^{\prime}\\ v_{y}^{\prime}\end{array} \right] \tag{18}\]  
and  
\[\left[ \begin{array}{c}v_{0}\\ v_{1}\\ v_{2}\end{array} \right]=-\frac{1}{2}\left[ \begin{array}{cc}2\cos\theta_{0}&2 \sin\theta_{0}&-1\\ \cos\theta_{0}+\cos\theta_{1}&\sin\theta_{0}+\sin\theta_{1}&-1\\ \cos\theta_{0}+\cos\theta_{2}&\sin\theta_{0}+\sin\theta_{2}&-1\end{array}  \right]\left[ \begin{array}{c}v_{x}^{\prime}\\ v_{y}^{\prime}\\ v_{D}\end{array} \right] \tag{19}\]  
for the physical target and active false target, respectively. For the physical target, it can be argued that there is a virtual deepection velocity of zero value. Therefore, the relationship Equations (18) and (19) can be uniformly expressed as  
\[\left[ \begin{array}{c}v_{0}\\ v_{1}\\ v_{2}\end{array} \right]=-\frac{\textbf{B}}{2}\left[ \begin{array}{c}v_{x}^{ \prime}\\ v_{y}^{\prime}\\ v_{D}\end{array} \right] \tag{20}\]  
Figure 2: Illustration of transformed coordinate system. where **B** is  
\[\textbf{B}=\left[ \begin{array}{ccc}2\cos\theta_{0}&2\sin\theta_{0}&-1\\ \cos\theta_{0}+\cos\theta_{1}&\sin\theta_{0}+\sin\theta_{1}&-1\\ \cos\theta_{0}+\cos\theta_{2}&\sin\theta_{0}+\sin\theta_{2}&-1\end{array} \right] \tag{21}\]  
Then, the vector \([\textbf{v}_{x}^{\prime},\textbf{v}_{y}^{\prime},\textbf{v}_{D}]^{T}\) can be obtained from Equation (20)  
\[\left[ \begin{array}{c}v_{x}^{\prime}\\ v_{y}^{\prime}\\ v_{D}\end{array} \right]=-2\textbf{B}^{-1}\left[ \begin{array}{c}v_{0}\\ v_{1}\\ v_{2}\end{array} \right]=-\frac{2\textbf{B}^{*}}{|\textbf{B}|}\left[ \begin{array} []{c}\textbf{v}_{0}\\ \textbf{v}_{1}\\ \textbf{v}_{2}\end{array} \right] \tag{22}\]  
where \(\textbf{B}^{*}\) and \(|\textbf{B}|\) are the adjoint matrix and determinant of the matrix \(\textbf{B}\), respectively. The deception velocity can be extracted as  
\[v_{D}=-\frac{2}{|\textbf{B}|}((s_{20}+s_{01}+s_{21})v_{0}+2s_{02}v_{1}+2s_{10 }v_{2}) \tag{23}\]  
\[|\textbf{B}|=s_{01}+s_{12}+s_{20} \tag{24}\]  
\[s_{ij}=\sin(\theta_{i}-\theta_{j}) \tag{25}\]  
and the estimation variance of the deception velocity is  
\[\sigma_{v_{D}}^{2}=E\Big{[}dv_{D}dv_{D}^{T}\Big{]}=\textbf{T}\boldsymbol{ \Lambda}\textbf{T}^{T} \tag{26}\]  
where **T** is the partial derivative vector, which can be derived from Equations (17) and (23)  
\[\textbf{T}=\left[