The price of a smallholding of several hectares is only the minimal sum needed to have it marked out and registered.

Under the precondition of ensuring the accuracy , the principle of discreteness choice is low-consumed and low-cost , which can make the apparatus work more time and spend less money.

The king principle is choose the lowest power consumption and inexpensive parts while can guarantee the device's accuracy so that to let this device can work long time outdoor and cheap.