Design And Realization Of Equalization In HF High Data Transmission

HF communication plays an important role in the wireless communications, due to its advantages of long range, good flexibilities, and strong subsistence. However, the performance of HF communications systems is influenced directly by three kinds of selective fading respectively on time, frequency, and space, as a result of the reflection of ionosphere. A research is made of the anti-fading and anti-noise power of the fractionally spaced equalization via the channel estimation of recursive least square algorithm, mainly aimed at wireless high data transmission. At the same time, a compare is made of strong/shortpoints between least mean square and recursive least square algorithms, as well as MLSE optimum receiver, Block Data Directed Estimation detection and fractionally spaced equalization. Theoretically shown, the fractionally spaced equalization has a sampling rate higher than the Nyquist rate so as to be insensitive to sampling phase, overleap a matched filter, which is superior to the symbol rate equalization. Besides, modulation/demodulation, frame structure and encoding/decoding are presented of MIL-STD-188-110A and MIL-STD-188-110B. Finally the above channel estimations and equalizations are accomplished, according to 110A on hardware flat or 110B by simulation.