| PISM ( PISM- Phase-Inversion Symmetric Modulation ) is invented by my tutor, professor Xiao Bao-jin . We can get weak signal in strong noise if we use this method, also SNR will be increased greatly. It is noticed by the civil and foreign professions in recent years. It is financed by NSFC 2006.In this paper, we study the theory of PISM. We clarify that PISM make use of the pertinence of the noise and its digital character to eliminate the noise. We begin to know the relation between PISM and Shannon principle.Based on the detailed investigation into the Phase-Inversion Symmetric Modulation with an equilibrium multiplier, a mathematical analysis for PISM to enhance the SNR is put forward. And a MATLAB model is built up to carry out numerical simulation, which visually proved the superiority performance of PISM.The importance of the paper is PISM-DSB. There is strong correlation between upper-sideband and lower sideband. We can convey two signals on the same frequency simultaneously. The simulations show feasibility of PISM-DSB. PISM-DSB has the same results with SSB. It also can convey two signals, but it is difficult to... |
