【摘要】 传统的相参处理器包括Ｉ，Ｑ二个通道，存在不可避免的幅相不平衡。本文研究对中频带限信号采样经数字处理获得零中频正交数字信号的方法。该方法只用一路Ａ／Ｄ变换器直接对中频带限信号进行采样和数字变换，用镜频抑制滤波器、二次重采样移频电路分离零中频信号的同相分量Ｉｎ和正交分量Ｑｎ。因而，该方法能够克服Ｉ，Ｑ通道不平衡。文中对中频频率、采样时钟周期的选择、镜频抑制滤波器的设计进行了详细讨论。选用具有线性相位特性的ＦＩＲ镜频抑制滤波器，不改变信号的相位特性。实验结果表明，该方法性能优良。用８阶ＦＩＲ镜频抑制滤波器，镜象电平抑制到－５０ｄＢ以下，相当于幅度不平衡小于０．０５ｄＢ，或相位误差小于０．３°。硬件实现结构也比较简单更多还原

【Abstract】 Studies a method of developing in-phase and quadrature samples of band-limited IF waveforms. The method employs only one analog to digital (A/D) convertor to sample and digitize the iF signal directly,eliminating the need for iF to be mixed to zero centre frequency in the form of two parallel baseband channels. An imaginary frequency rejecting filter and a secondary resampling circuit for frequency shifting are used to provide in-phase and quadrature components I and Q from the digital samples. Thus the problem of match.ing gain and phase response difference between the two components is avoided. The digital frequency shifting circuit is simplified by properly selecting the iF carrier and the sample interval. Experimental results show that the imaginary frequency level of less than-50’.dB is obtained by using an & order filter. That is to say,the equivalent gain error is less than 0.05dB,or the equivalent phase error is less than 0.3 degree. The hardware implementation is relatively simple.更多还原