Aiming at requirements of long time field area soil moisture monitoring and large quantity of data collection

soil moisture retrieving system

Bei Dou satellite system-reflectometer（ BDS—R） based on wireless transmission is proposed. Constituted by UM220—Ⅲ N and GPRS DTU modules as its core

Bei Dou signal processing and wireless data transmission modules are built up

Bei Dou signal are collected by circularly polarized antenna and processed into NMEA 0183 format serial data and transmitted to wireless serial server COMWAY via GPRS and the Internet. Log on serial server and use data saving software compiled by Microsoft Visual Studio 2008 software to extract data and save it into local disks. One month consecutive signal information of Bei Dou C05 satellite are selected for soil moisture inversion experiment by reflection coefficient method

correlation coefficient between inversion results and the in-situ humidity values reach to 0. 69

average relative error is 16. 86 %

which proves that reliability of the system is really good

it is suitable for long distance field area soil moisture inversion for a long time.