甚小线性调频键控调制波形的功率谱优化

甚小线性调频键控(very minimum chirp keying,VMCK)是一种高效的超窄带调制技术,其优点表现在宽带占用窄、边带抑制强、数据传输效率高等方面.直接由VMCK的信号表达式推导出的功率谱解析表达式中包含一个不可积分函数,导致结果复杂且不精确.通过正交拟合方法对功率谱进行分析,发现其功率谱中不仅包含携带信息的连续谱,而且包含携带载波的线性谱.由于线性谱并不携带发送信息,并严重影响功率谱的边带抑制,使得调制信号抑制性能降低.为得到带宽更窄、边带抑制能力更强的VMCK信号,更好地满足超窄带系统要求,对VMCK信号进行波形优化,在滤除线谱的同时,使信号调制性能得到提高.

Optimization of Very Minimum Chirp Keying Modulation Waveforms to Eliminate Linear Spectrum

Very minimum chirp keying(VMCK) is a highly efficient ultra-narrowband modulation technique,which has the advantage of narrow band occupancy,intensive sideband suppression,and higher data transmission efficiency.However,if we directly derive the analytical expression of its power spectrum from VMCK signal expression,the result is complex and imprecise because the result contains a non-integral function.Linear spectrum does not carry useful information.In order to obtain narrower bandwidth,stronger sideband suppression and better demodulation performance,we remove the harmonic spectral lines in power spectrum by separate sinusoidal basis fitting to optimize VMCK.