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In this tutorial paper we present equalization techniques to mitigate inter-symbol interference (ISI) in high-speed communication links. Both transmit and receive equalizers are analyzed and high-speed circuits implementing them are presented. It is shown that a digital transmit equalizer is the simplest to design, while a continuous-time receive equalizer generally provides better performance. Decision feedback equalizer (DFE) is described and the loop latency problem is addressed. Finally, techniques to set the equalizer parameters adaptively are presented.

In this paper, a Tactical Data Link Communication System (TDLCS) simulation model mainly consisted of frequency-hopping spread spectrum (FHSS) module has been built by using the Simulink platform in Matlab. The single tone interference signal was added into this simulator. Frequency spectrogram figures and Bit error rate (BER) curves are obtained after simulations, which indicate that the frequency-hopping (FH) module of the TDLCS has a good ability to resist single tone interference.

Data transmission is affected by factors such as multipath effect, noise, time varying and Doppler effect in HF channel. In comparison with traditional equalization, turbo equalization is a better approach to these problems. In this paper, we build a simulation model of turbo equalization in HF communication system based on the characteristics of HF channel, comparatively analyze of the effect of some parameters such as length of interleaver, number of iterations and convolutional encoder. Subsequently the burst waveform in MIL-STD-188-141b and the MMSE-based turbo equalizer was developed, thus providing a reliable basis for the application of Turbo equalization in HF channel. The simulation illustrates that the MMSE-based Turbo equalization can reduce the gap between the simulation BER curve and theoretical curve, alleviating the impact of multipath fading, noise and Doppler effect; providing a high value and extensive application prospect.