重复性门控技术为什么测量工作频率为4倍

Joel博士，在本书第9章的第一部分中，您将详细了解PCB夹具特性。
您提到了对所有标准的连接器进行门控的技术，以通过计算连接器的矢量差来查看连接器的可重复性。
在该讨论中，您提到测量感兴趣的工作频率为4倍是个好主意。
为什么是这样？
编辑：忘了提。
你提到将门的中心放在连接器周围，并设置一个跨度，使得门挡位于直通中心周围。
100ps中心，1040ps跨度的例子就是我所说的。
我没有时间域控制VNA。
我依靠PLTS这一点，通常从sparameters开始我所有的时域配置文件大约是200ps。
这可能完全是点问题，但在数学上听起来我在使用PLTS时技术是有限的（即门跨度）。
这里有什么问题吗？
我一直在练习，我通常只是看着脉冲响应并将门设置在连接器之后的一个点，其中脉冲消失为0（连接器后大约一点点）。
希望这是有道理的。
更新编辑：现在感觉有点傻。
看着图片，你可以清楚地看到大门的起点和终点。
我绝对不会看到门跨度为1040ps。
谢谢，-KTB编辑：KTB于2015年10月15日9:26 AM编辑：KTB于2015年10月15日上午9:42



     以下为原文

  Dr. Joel,

In the first section of chapter 9 of your book, you go into detail about PCB fixture characterization. You mention the technique of gating the connectors of all the standards to see the repeatability of the connectors by calculating the Vector Difference of them. In that discussion, you mention that it is a good idea to have a measurement of 4x the operating frequency of interest. Why is this?  

Edit: Forgot to mention. You mention putting the center of the gate around the connector with a span set to where the gate stop is around the center of the thru. The 100ps Center with 1040ps span example is what I'm talking about. I don't have timedomain gating on the VNA. I rely on PLTS for this and typically the start of all my time domain profiles from sparameters is roughly around 200ps. This may be completely point question, but it mathematically sounds to me that the technique is limited (that is the gate span) when using PLTS. Is there any real problem here? I've been practicing and I've typically have just been looking at impulse responses and set the gate to a point after the connector where the impulse dies to 0 (roughly a little bit after the connector). Hope this makes sense.

Update Edit: Feel kind of silly now. Looked at the pictures and you can clearly see the start and stop points of the gate. I definitely don't see see gate span being 1040ps.

Thanks,
-KTB

Edited by: KTB on Oct 15, 2015 9:26 AM

Edited by: KTB on Oct 15, 2015 9:42 AM