LabViewFM模拟调制解调。采用正交调制，解调利用希尔伯特变换得到幅度信息。稍加改动可以在NI USRP上仿真。(LabViewFM analog modulation demodulation. Quadrature modulation and demodulation are used to obtain amplitude information by Hilbert transform. A little change can be simulated on NI USRP.)