一阶差分运算公式: y [ n ] = x [ n ] − x [ n − 1 ] y[n] = x[n] - x[n-1] y[n]=x[n]−x[n−1] 一阶差分的频率响应 先得到其冲激响应: h [ n ] = δ [ n ] − δ [ n − 1 ] h[n] = \delta[n] - \delta[n-1] h[n]=δ[n]−δ[n−1] 对冲激响应进行傅里叶变换: H ( e j