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我一直在使用示波器超过30年,并认为我非常了解它们。
我过去购买了几个高端示波器,不得不承认触发器规格在我的关注列表中并不高。 他们刚刚工作! 在获得一个不会在干净的正弦波(安捷伦源)上触发1GHz以上的个人54846A后,我决定应该阅读该规范。 令人惊讶的是,这款2.25GHz示波器的触发灵敏度仅高达1GHz。 那么会发生什么? 有趣的是,它*会*触发非常快速的事件,如雪崩脉冲发生器或空中ESD事件(当然距离),上升时间低于200ps。 但它无法处理正弦波。 我查看了源输出,它的光谱非常干净。 在另一个3GHz示波器上,正弦波是完美的。 范围是否破裂? 所有渠道的行为都相同。 删除了cal文件并运行完整的cal而没有任何变化。 单元非常干净,提供最新的软件版本,也是最后一个最快的主板。 我意识到当前的模型有很多改进的触发。 在另一个未提及的示波器品牌中,我总是能够在混叠和其他事情发生之前触发指定的范围带宽。 以上来自于谷歌翻译 以下为原文 I've been using scopes for over 30 years up to the latest and thought I knew them fairly well. I've purchased several high end scopes in the past and have to admit that trigger specifications were not high on my list of concerns. They just worked ! After acquiring a personal 54846A which will not trigger above 1GHz on a clean sine wave (Agilent source), I decided I should read the spec. It was surprising to find that trigger sensitivity for this 2.25GHz scope is only spec'd up to 1GHz. So then what happens ? Funny thing is that it *will* trigger on very fast events like an avalanche pulser or airborne ESD event (from a distance of course) with risetimes below 200ps. But it just can't handle a sine wave. I've looked at the source output and it is very clean spectrally. On another 3GHz scope, the sine wave is perfect. Is the scope broken? All channels are identical in behavior. Deleted cal files and ran full cal with no change. Unit is very clean and has the last software version offered and also the last, fastest motherboard. I realize that current models have much improved triggering. On another unmentioned brand of scopes I've always been able to trigger right up to the specified scope bandwidth before aliasing and other things kick in. |
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4个回答
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通常,范围的HW Trigger BW过去大约是范围BW的一半。
还有灵敏度规格,因此根据信号幅度,您可以触发更高的BW信号。 较新的Agilent / Keysight示波器具有“触发灵敏度”按钮,可以提供更高的BW触发。 也就是说,还有数字示波器“伪造”更高的BW。 它们使用隐藏的“自动”触发模式(如果在短时间内没有触发事件则强制触发),然后在SW中寻找迹线中心附近的边缘,并将其移动到显示中间 。 如果它发生得足够快,则与“真实”触发器无法区分。 要确定这是否正在进行是非常困难的。 您没有在3 GHz示波器上标明该品牌,或者您用于测试它的正弦信号的频率,因此我无法对该部分发表评论。 人 以上来自于谷歌翻译 以下为原文 Generally, the HW Trigger BW of scopes, in the past, has been approximately half the scope BW. There are also sensitivity specifications, so depending on the signal magnitude, you can trigger on higher BW signals. Newer Agilent/Keysight scopes have a "Trigger Sensitivity" button, that can give higher BW triggering. That said, there are also digital scopes that 'fake' a higher BW. They use a hidden 'Auto' trigger mode (which forces a trigger if there's no trigger event within a short period of time), then look for an edge near the center of the trace in SW, and move that to the middle of the display. If it happens fast enough, it is indistinguishable from a 'real' trigger. It's very hard to determine if this is being done. You don't indicate the brand on the 3 GHz scope, or the frequency of the sinusoidal signal you used to test it, so I can't comment on that part . Al |
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nvywyerwer 发表于 2018-10-26 17:29 嗨Al,谢谢你的快速回复。 我正在应用1GHz到2.5GHz之间的干净正弦波,但是当它不会超过1GHz时,暂停我的“新”示波器的BW测试。 (它实际上会触发高达1.2GHz左右,但迹线上有很多抖动)。 昨晚我在服务手册中运行了触发灵敏度测试并通过,但测试仅在100MHz,500MHz和1GHz。 “其他”是TDS694C,它提供了几乎高达3GHz(其BW)的干净触发波形。 对于这个型号,没有超过1GHz的规格,我可能没有任何支持将这个范围归还给经销商。 我们有3000X(1GHz)和4000X(2.5GHz)的工作,我注意到触发器规格不再提到什么频率(据我记得)。 同样对于其他品牌。 它是Y范围敏感但不依赖于频率。 这些模型正在将我转换为安捷伦,但我的家庭实验室预算称“旧安捷伦”。 那么,如果这个范围在1GHz处触发“ok”,你会说这对于模型来说是正常的吗? 谢谢你的帮助。 巢穴 以上来自于谷歌翻译 以下为原文 Hi Al, Thanks for the quick reply. I was applying a clean sine wave between 1GHz and 2.5GHz, but suspended the BW test of my "new" scope when it wouldn't get past 1GHz. (it will actually trigger at all up to around 1.2GHz but with much jitter on the trace). Last night I ran the trigger sensitivity test in the service manual and it passes, but tests are only at 100MHz, 500MHz and 1GHz. The "other" was a TDS694C and it delivers a cleanly triggered waveform almost up to 3GHz (its BW). SInce there is no spec beyond 1GHz for this model, I may not have a leg to stand on for returning this scope to the dealer. We have a 3000X (1GHz) and 4000X (2.5GHz) at work and I noticed that the trigger spec no longer mentions at what frequency (as far as I recall). Likewise for the other brand. It is Y range sensitive but not frequency dependent. These models are converting me to Agilent but my home lab budget says "old Agilent". So, if this scope triggers "ok" at 1GHz, would you say that was normal for the model? Thanks for your help. Den |
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nvywyrww 发表于 2018-10-26 17:45 是的,我会说,因为它在1GHz触发,它按指定工作。 它在1.2 GHz处“抖动”的事实证明,至少在我看来,这是一个真正的触发器,而不是我提到的“假”触发器之一。 3000X和4000X仅在不同带宽的触发灵敏度方面讨论触发BW。 对于人们使用更高速度范围进行的许多测量,边缘触发BW变得不那么重要了。 例如,在查看抖动时,触发位置根本不是等式的一部分。 唯一重要的是时基和边缘的位置。 人 以上来自于谷歌翻译 以下为原文 Yes, I would say that since it triggers at 1GHz, it is working as specified. The fact that it's "jittery" at 1.2 GHz is proof, at least to me, that it's a real trigger, not one of the "fake" triggers I mentioned. The 3000X and 4000X only talk about trigger BW in terms of trigger sensitivity at different bandwidths. For many measurements that people are making with higher speed scopes, Edge trigger BW becomes less important. When looking at jitter, for instance, the trigger location is not part of the equation at all. The only thing that matters is the timebase, and the location of the edges. Al |
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nvywyerwer 发表于 2018-10-26 18:01 再次感谢Al。 我决定对此进行实际操作,并在真实世界的应用程序USB HS验证中进行尝试。 触发器足够好但不太重要,因为测试是针对来自单脉冲的数据完成的,由脉冲宽度条件触发。 它运行良好,并且在易用性和快速存储方面击败了旧的TDS(Win98下的旧的1GB闪存驱动器)。 巢穴 以上来自于谷歌翻译 以下为原文 Thanks again Al. I decided to be practical about this and try it in a real world application, USB HS verification. The trigger was good enough but of less importance since the test is done on data from a single sweep, triggered by a pulse width condition. It worked flawlessly and blows away the old TDS in terms of ease of use and fast storage (good old 1GB flash drive under Win98). Den |
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