Research Of Key Technologies Related To The High Speed Data Transmission In HF Communication

Based on the 3G shortwave communication network protocol,MIL-STD-188-141B, the paper studies on the key technologies of high speed data transmitting burst waveform BW2 in physical layer of shortwave telecommunication,and also its sending and receiving projects are designed and realized. In the process of system design, the adaptive equalization technology of the receiving part is chiefly researched.As typical parameter-changing channels, the inter-symbol interfere(ISI) phenomenon is caused by multi-path dispersion and signal fading in the process of shortwave telecommunication. For these reasons, the system’s performance is seriously decreased, even out of action. Therefore, the design of adaptive equalizer is especially important. Based on the study of the whole sending and receiving projects, the paper simply introduces the basic theory of adaptive equalization; then aimed at inherent shortcoming of the decision feedback equalizer-error propagation, an improved adaptive equalizer is presented on the basis of previous equalizer (it adopts square root Kalman algorithm). The new equalizer structure utilizes decision error, defines a test statistics to compare with the decision threshold and the decision is classified as reliable and unreliable decision, then deals with it variably. At last, the fractionally-spaced equalizer is applied in the improved equalizer. The equalization performance is tested in MATLAB simulation environment, and the result proves that the performance of the equalizer improves greatly.Based on the result of simulation, the schemes of transmitter and receiver have been implemented on TMS320C5509 DSP supplied by TI company, especially the implement procession of the adaptive qualization.