数字基带系统将数字信号从时域上看时数字滚降，需要画出滚降前后的波形展示出来。频域上带宽变化了。输入滤波器之前的波形与采样判决之后的波形。采样判决前的频谱。

采样判决后的码型。

2、眼图（采样判决之前的眼图）（信噪比大眼图清晰）

3、误码曲线，（横坐标时信噪比，纵坐标时误码率）

4、Arfa变化对误码特性的影响，变好还是变差(变好)，眼图清晰度变化（清晰），传递函数的带宽的变化。（带宽越大）-1.Digital baseband system point of view the digital signal from the time domain when the number of roll-off, you need to draw the waveform displayed before and after the roll-out. The frequency domain, the bandwidth change. Input filter and sample ruling before the wave after wave. Sample pre-judgment spectrum.

Sampling pattern after the verdict.

2, the eye diagram (eye before sampling decision) (SNR big eye clear)

3, the error curve (abscissa when the signal to noise ratio, bit error rate when the vertical axis)

4, Arfa impact of change on BER performance, get better or worse (getting better), change of eye-definition (clarity), the transfer function of the bandwidth changes. (The greater the bandwidth)