A Novel Structure of Signal Demodulation in High Frequency (HF) Channel

In this paper, a novel demodulation structure in high-frequency (HF) channel is introduced and studied. Frequency-offset estimation, fractionally spaced adaptive equalization and carrier recovery techniques are involved. Frequency-offset correction is carried out based on channel impulse response estimation. Fractionally spaced adaptive equalization and carrier recovery are combined with non-linear decision feedback loop structure, and the initial value of tap coefficients of equalization are obtained from the previous channel estimation. Simulation is conducted under channel parameters with respect to MIL-STD-188-110B using a Monte Carlo technique. The results show this novel demodulation structure is feasible and efficient in HF channel, the symbol error ratio can reach to 10^-3 in 12 dB SNR.