抄録
The signal points more than 3000 points were selected for the examination. The items of the examination are the followings;
1. On the problems of shapes and its standardization of the signal points.
2. On the problems of the vegitation around the signal points.
3. On the problems of the height of the signal points above the ground.
4. On the problem of the height position of the signal points above the mean sea level.
5. On the problem of the eccentricity of the signal points.
6. On the problem of duration of the signal points in the fields.
From the result of these statistical examinations, the author concluded that the best signal points are placed in the wet rice field and cultivated field with shape of Y and + marks and, it is hoped, these signals are placed just befor the air flight.
