Keysight Probe Video - Helpful details on how to get signals into your scope - Page 1
Forum section: electronics / testgear

author: rx8pilot
author_rank: Super Contributor
timestamp: August 31, 2016, 02:57:14 am
content: There is a regular heartbeat of conversation on this forum that comes down to probe techniques. I have spent considerable time learning how to best get signals into my scopes and now that I am pushing toward multi-Ghz circuits I need to learn even more.This presentation on probing is nicely done and a lot to learn. Does the squiggly line on the screen represent what is happening in your circuit? Are you mangling the signal you are hoping to measure in the process of measuring? There are only a handful of conversations that talk about techniques related to getting signals into a scope with as little signal damage as possible.No, I don't work for Keysight but I have been scouring all of their papers and videos on test and measurement topics. Most of it is cold corporate communications but the underlying content has really sharpened my T&M knowledge and skill.https://youtu.be/_j1FjTrZrU4?list=PLzHyxysSubUlKfrZIcXfXhJwhRwLVnKq1

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: August 31, 2016, 07:55:56 am
content: Quote from: rx8pilot on August 31, 2016, 02:57:14 amI find that, quite often, very little thought is put into probing and proper probing techniques.QuoteWell, Keysight does have an awful lot to offer in regard to documentation, which is a stark contrast to most of its competitors. It's a shame that most of it is marketing-infested but if you can separate marketing from facts then their documents provide a great ressource.For those that don't like videos, here's a very good tutorial in pdf format that explains the in's and out's of probing and the maths behind it (and it's a bit less marketing infested):http://cdn.teledynelecroy.com/files/appnotes/lecroy_probing_tutorial_appnote016.pdf

author: AndyC_772
author_rank: Super Contributor
timestamp: August 31, 2016, 08:22:07 am
content: Tektronix also has an excellent guide to probe fundamentals... essential reading for anyone using a scope, IMHO.http://circuitslab.case.edu/manuals/Probe_Fundamentals-_Tektronix.pdf

author: rx8pilot
author_rank: Super Contributor
timestamp: August 31, 2016, 04:31:58 pm
content: Quote from: Wuerstchenhund on August 31, 2016, 07:55:56 amIn the end, selling equipment pays for the expense of documentation so I guess that is all fair. It can be hard to gain intuition about how to use test equipment effectively. Since my new and exciting scope arrived from Keysight, I want to be able to take full advantage of it to best benefit my business. There are so many traps and dark places that can send a user on tail chasing adventure only to find out that they were the source of the anomaly or did not know how to interpret the results. I have a long list of stories like that for sure. Aside from probing - it is also fun to understand what the various pieces of equipment are used for in terms of analysis. So many times I am asking myself 'Why would someone need that?' After reading or watching a video - I learn what can be accomplished with a specific feature or piece of equipment and that gives me ideas and inspiration.The more I learn about T&M equipment and technique, the more confidence I build in tackling more challenging designs. My end-goal is to design and manufacture new products and they all benefit from being able to quickly and accurately measure and analyze.

author: Keysight DanielBogdanoff
author_rank: Unknown
timestamp: September 01, 2016, 04:27:30 pm
content: What I like most about this video is that it covers some of the trade offs of why we make probes the way we do.I'd also point out that there are time tags in the video description that let you skip ahead to topics that look most interesting to you.

author: tggzzz
author_rank: Super Contributor
timestamp: September 01, 2016, 04:55:24 pm
content: For written information to complement the video, have a look at the references athttps://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/As others have said and implied, correct probing techniques are vital if you want the scope to show anything valid.

author: rx8pilot
author_rank: Super Contributor
timestamp: September 01, 2016, 08:14:02 pm
content: Quote from: Keysight_DanielBogdanoff on September 01, 2016, 04:27:30 pmComing from a background in cameras and cinematography - I see probes like a photographer see lenses. The best camera on earth cannot do anything without a lens. Using a poorly chosen lens for your photo will result in a different photo than you were expecting. The photographer with only one lens will look for subjects and opportunity that fits the capability of that particular lens. The photographer with a huge variety of lenses looks for an opportunity and pulls out just the right lens to capture that moment. A low skill photographer with a giant pile of amazing lenses lenses will still capture images that are not interesting, out of focus, or improperly exposed.I would like to have all the probes AND the appropriate skills to use them effectively. My collection is growing as can afford them and have projects appropriate for them as well.Quote from: tggzzz on September 01, 2016, 04:55:24 pmAs Dave may say....."It's a trap for young players". About two years ago, I spent days trying to solve a 'problem', but the problem is that I was overdriving an active probe. It was getting into the non-linear region of the probe but I did not know that. I thought my circuit was the problem. Nuts. Painful.

author: TheSteve
author_rank: Unknown
timestamp: September 03, 2016, 03:58:07 am
content: I enjoyed listening to this probe video, there wasn't too much new information but a refresher never hurts. I also spent some time verifying the total system bandwidth of my 500 MHz scope when combined with a 500 MHz probe. As Keysight claims the combination still easily exceeds the 500 MHz bandwidth specification(3dB point was still 550 MHz).I also compared circuit loading between a passive and active probe, as expected the active probes blows away the passive probe as it loads much less and gives a much more accurate amplitude measurement at higher frequencies.