21072624
2012-10-28, 22:06
有高手可以指導一下嗎?
Suppose that there is a radio antenna, that is broadcasting a radio signal. We do not know where this antenna is, but we have made precise measurements of the signal strength at different locations. We also know that the strength of a signal (also called the Power Density measured in Watts/meters2) decreases with the square of the distance from the source. (This is the inverse square law). Specifically, the Power-Density is given by the following equation: S = P/(4 π R2) where S is the signal strength, P is the power supplied to the antenna (in Watts), and R is the distance from the antenna to the tower. Using the measurements and the inverse square law we would like to work out the location of the antenna, and its power. There will be 3 measurements that record the location (X and Y coordinates, in meters) along with the power density (in mW/m2). Given three power density measurements from three know locations, we can traingulate the origin of that signal, and its power. For three measurements of:
X (m) Y (m) S (mW/m^2)
0 0 0.5
0 1000 1
2000 0 0.5
We can triangulate the location of the antenna to be two possible locations: (1000,1000) or (1000,3000)
http://undergraduate.csse.uwa.edu.au/units/CITS2401/laboratories/triangulate.png
Suppose that there is a radio antenna, that is broadcasting a radio signal. We do not know where this antenna is, but we have made precise measurements of the signal strength at different locations. We also know that the strength of a signal (also called the Power Density measured in Watts/meters2) decreases with the square of the distance from the source. (This is the inverse square law). Specifically, the Power-Density is given by the following equation: S = P/(4 π R2) where S is the signal strength, P is the power supplied to the antenna (in Watts), and R is the distance from the antenna to the tower. Using the measurements and the inverse square law we would like to work out the location of the antenna, and its power. There will be 3 measurements that record the location (X and Y coordinates, in meters) along with the power density (in mW/m2). Given three power density measurements from three know locations, we can traingulate the origin of that signal, and its power. For three measurements of:
X (m) Y (m) S (mW/m^2)
0 0 0.5
0 1000 1
2000 0 0.5
We can triangulate the location of the antenna to be two possible locations: (1000,1000) or (1000,3000)
http://undergraduate.csse.uwa.edu.au/units/CITS2401/laboratories/triangulate.png