示波器中的Trigger

原創

2020-05-06 09:58

什麼是Trigger，它在示波器中的作用是什麼？

先來看看別人是怎麼說的。

The trigger event establishes the time-reference point in the waveform record. All waveform record data is located in time with respect to that point. The instrument continuously acquires and retains enough sample points to fill the pretrigger portion of the waveform record. That is the part of the waveform that is displayed before, or to the left of, the triggering event on screen. When a trigger event occurs, the instrument starts acquiring samples to build the posttrigger portion of the waveform record, that is, the part displayed after or to the right of the trigger event. After a trigger is recognized, he instrument will not accept another trigger until the acquisition is complete and the holdoff time has expired.

trigger事件是在被抓到的波形中建立一個時間參考點。所有的被抓到的波形以這個時間點來排序。設備在這個時間點到來之前（pretrigger）會一直抓取和保存數據，這些數據會被用來繪製trigger時間點之前的圖；當trigger事件發生之後，設備在這個時間點到來之後（posttrigger）也會一直抓取和保存數據，這些數據會被用來繪製trigger時間點之後的圖。

當設備識別到了一個trigger的時候，它在抓取完成之前和holdoff時間之前不會接受另外一個trigger。

The trigger event defines the point in time at which a repeating “window” of waveform information is stabilized for viewing. Imagine you are taking a trip in your car. You need to arrive at your destination in the minimum amount of time, but you want to photograph a particular landmark along the way. You know you can get to your destination quickly because you have a very fast car, but what’s your strategy for capturing the point of interest on film? One choice would be to randomly snap pictures on your camera as you drive and hope to capture an image of the landmark. Obviously this leaves too much to chance.
A more logical approach would be to give the driver instructions on where to stop so you can get a good clean picture of your point of interest.

trigger事件是用來定義一個時間，來讓一個重複的信號可以被我們穩定的觀測到。
想象一下，你在開車去一個地方，但是要求你必須在最短的時間內到達。但是你有像在這期間拍攝一張一個特定地點的地標照片，你怎麼辦？
一種辦法是隨機的拍照片，但是你的運氣需要足夠好，可能才能拍到你需要的照片。
一個更好的辦法是：到達地標建築的時候，把車停下來，拍一張照片，接着走。