软件无线电中调频波形的正交解调

Quadrature demodulation of FM waveform in software defined radio

为了满足软件无线电电台中通用波形库的设计要求,研究了软件无线电中FM波形的数字化解调,分析了用坐标旋转数字计算机(CORD IC)算法,计算FM基带解析信号相位的过程。给出了FM正交解调结构,即在统一的中频数字化硬件平台上,与单边带、调幅等波形一起在基带完成正交解调。在此基础上,提出了一种采用相位校正的差分鉴频方法,并针对DSP实现形式对CORD IC算法进行了改进。该算法与传统的非相干解调方式相比,在灵活性和可靠性方面有了较大的增强。

In order to meet the requirement of general waveform programming in software defined radio, digitalized demodulation of FM waveform was studied. The CORDIC （coordinate rotation digital computer） algorithm for calculating phase of FM baseband analytic signal was analyzed. The architecture of FM quadrature demodulation was provided. On the universal IF digitalization hardware platform, FM waveform was demodulated in base-band together with SSB and FM. Based on this, a differential discriminator using phase correcting method was proposed, and a modified CORDIC algorithm was also implemented by DSP. Compared with the existing non-coherent demodulation scheme, the algorithm has some improvement in flexibility and reliability.