Reversalpointmethod which is adopted by gyroscope to seek north at present reduces the speed of north-seeking and is hard to make the instrument automatic.
目前陀螺初寻北大多还是采用逆转点法，影响寻北速度且难以实现仪器自动化。
2
Based on the focalization ability of time reversal theory to the wave origin, the wave propagation was rebuilt by an image method which displays the damage as the focusing point.