The near surface scattered wave can be caused by near surface topographical relief and variation of lithological change,this secondary interference is similar to reflection and diffraction in time distance relation and character of frequency,which brings about some difficulty in its recognition and suppression on the records.

By using Mel nikov functions,for the Poincare bifurcation problems of quadratic Hamiltonian system under cubic perturbation with one center and the periodic regions,which has a parabola and an invariant straight line as it s bounding.

The effect of filter bandwidth in soft limiting satellite transponder with uplink interference is studied.

Taking example by direct sequence spectrum spreading system, firstly the link performance of transparent transponder satcom system is analyzed with uplink interference (or jamming) and then the theory derivation is made.

Firstly the performance of transparent transponder satcom system is analyzed to uplink interference (or jamming) and the closed expression for calculating BER performance is given.