【摘要】 传统的基于离散傅立叶变换(DFT)的频移键控(FSK)信号解调在同步检测中采用了固定门限,无法适应时变信道环境中信号衰减和噪声干扰的动态变化,实际应用中效果不佳。为了解决这个问题,首先在分析传统方法固有缺陷的基础上,提出了自适应门限同步检测的思路,然后应用随机信号检测与估计相关理论对检测算法进行了详细推导,并给出了自适应门限的计算公式,最后对算法的有效性及性能进行了仿真与分析,结果表明该方法所得的同步检测门限在不同信噪比情况下均能适应信道环境的动态变化,其虚警概率和检测概率的性能与理论相符,有效解决了时变信道环境下门限选择的问题。更多还原

【Abstract】 A Fixed threshold is usually used for synchronous detection in traditional Frequency Shift Keying(FSK) system based on Discrete Fourier Transform(DFT).The disadvantage of the fixed threshold is that it cannot adjust itself dynamically to the change of signal fading and noise jamming in a time-varying channel,which makes the system unsuitable for practical applications.To solve this problem,a novel adaptive threshold demodulation method based on random signal detection and estimation theory is proposed.Then the rigorous theoretical proofs are shown,and the definite expression of the adaptive threshold is given.Finally,simulation results show that the adaptive threshold can adapt to the channel condition change under different signal-to-noise ratios(SNR).And the false alarm and detection probabilities agree well with the theoretical analyses.The algorithm can effectively resolve the problem of the threshold-choosing in the time-varying channel.更多还原