2015年9月30日 星期三

29 September 2015

Principle of TDOA
In time different of arrival, at the beginning, all base stations are synchronized. 

There are three access points (AP1, AP2, AP3), when a client transmits a signal like a sound wave, each of access points will produce a time of arrival measurement. 

 Equations of TDOA can be obtained.
\begin{align} & \sqrt{(x-x_1)^2+(y-y_1)^2}-\sqrt{(x-x_3)^2+(y-y_3)^2} \\ =\, & c(t_1-t_3) \\ & \sqrt{(x-x_2)^2+(y-y_2)^2}-\sqrt{(x-x_3)^2+(y-y_3)^2} \\ =\, & c(t_2-t_3) \end{align}
In the above equations, AP1(x1,y1), AP2(x2,y2), AP3(x3,y3)

 Each TDOA equation is a hyperbola, so the target location can be located as the intersection point of equations.    
張貼者： 於

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