According to the deficiency of Timed Abstract State Machine (TASM), TASM is extended with the data type of arrays, a loop rule named “while”, and some operators such as “%”,“&”, “|”, “^”, “>>”, “<<”, etc. The syntax and semantics of the extended TASM are defined. The extended TASM is applied to actual real-time embedded software to validate its effectiveness for requirements modeling.

Based on the Vector Radiative Transfer(VRT) theory and the characteristics of the SAR technology, several sub-models for rice backscattering are constructed, including the leaf scattering model, the leaf extinction model, the trunk scattering model, the trunk extinction model and the water reflection model. Then an integrated model for the first-order scattering mechanisms of rice, including all the main physical processes, is achieved. Based on the simulation results, it is discussed that the variations of the rice backscattering coefficient with the date, incidence angle, wave band, and polarization.