Fundamentals of IF (Intermediate Frequency) bandpass signal sampling and quadrature detection are discussed, especially the coherent mixing LPF method and Hubert transform frequency-shift method.

• 摘要结合对带通采样定理的理解，讨论了直接中频带通信号采样正交检波的基本原理，重点探讨正交混频低通滤波法和希尔伯特变换频移法。