Author Topic: Beginners Guide to Digital Oscilloscope  (Read 7108 times)

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Offline jacklee

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Beginners Guide to Digital Oscilloscope
« on: March 14, 2017, 10:13:09 am »
I'm going to write something about how to use oscilloscope generally. I think it could help me understand oscilloscope better, if it could also help you, it would be more pleasure for me.

I'll give the contents out first at the below, so you'll know what I'm going to write in the next days.

Preface
Basic Parts
Chapter 1 Types of oscilloscope
1) Desktop oscilloscope
2) Portable oscilloscope
3) Handheld oscilloscope
4) Tablet oscilloscope
Chapter 2 Introduction to probes
Chapter 3 Test a Signal
Chapter 4 Probe Compensation Calibration
Chapter 5 Vertical System Adjustment
1) Open and close channel
2) Vertical Scale
3) Vertical Position
Chapter 6 Horizontal System Adjustment
1) Horizontal Scale
2) Horizontal Position
Chapter 7 automatic measurement
1) Portable oscilloscope
2) Handheld oscilloscope
3) Tablet oscilloscope
Advanced Parts
Chapter 8 Know more vertical systems
1) Input coupling method
2) Probe
3) Bandwidth limitation
4) Reverse
5) Input impedance
Chapter 9 Know more horizontal systems
1) Sampling mode
2) Roll mode
3) ZOOM mode
4) XY mode
5) Memory depth
Chapter 10 Cursor Measurement
Chapter 11 Waveform Storage and Calling
Chapter 12 Screenshot
Chapter 13 Trigger
1) Trigger source
2) Trigger level
3) Trigger type
4) Trigger suppression time
5) Trigger coupling
6) Trigger mode
7) Single / Single SEQ
Chapter 14 Oscilloscope common settings 
1) High refresh
2) Gray Introduction
3) Display
(1) Waveform display setting
(2) Graticule settings
(3) Persistence adjustment
4) Language
Chapter 15 Conclusion

If you also have any suggestion or find out any error I made, it would be very welcome to tell me directly.  ^-^
« Last Edit: March 14, 2017, 10:15:48 am by jacklee »
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Offline Cliff Matthews

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Re: Beginners Guide to Digital Oscilloscope
« Reply #1 on: March 14, 2017, 11:17:30 pm »
The contents seem fine. These days, mso, arb-gen, etc.. are also getting included at near entry-level prices. Food for thought (I saw this early today): Some unanswered posts ask too much or don't "cut to the chase" quick enough. Perhaps this should have been posted in an existing sticky "Oscilloscope training.." or "Electronics primers, course material.."?
 

Offline DimitriP

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Re: Beginners Guide to Digital Oscilloscope
« Reply #2 on: March 14, 2017, 11:39:08 pm »
Quote
I think it could help me understand oscilloscope better,

I don't mean to rain on your parade, but .... (open umbrella)
Isn't all that covered by most oscilloscope manuals?
(Which enough new scope owners don't seem to either read or understand or both ?)

As for the value of writing instructions or explanations for something you, yourself is trying to get a handle on, well...that can go either way....

(close umbrella)



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Offline hurricanehenry

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Re: Beginners Guide to Digital Oscilloscope
« Reply #3 on: March 15, 2017, 02:58:45 am »
I agree that if you are going to just describe the functions, the user manuals will do a better job (especially since they are specific to the unit controls).

HOWEVER, if you are going to include some BASIC CIRCUITS in every chapter to help a newcomer understand each different feature of a scope, that is a totally different thing and I would 100000% agree this is something of value you can do for the community.

e.g., start with some very basic measurements of DC voltage, including capacitor charging, and then go on with some more advanced circuits that create more complicated waveforms, and then to AC, and then how to check for key bounces, etc.
 

Online Brumby

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Re: Beginners Guide to Digital Oscilloscope
« Reply #4 on: March 15, 2017, 04:09:27 am »
A user manual is just going to show you what the feature is and its specifications - and how to find in on multi-level menu setups.

What it won't show you is where you would use it and why.  These are rather important for absolute newbies, which is what the price/performance trend is allowing more and more.

When I got my first scope, people who wanted one needed to justify the expenditure - and knew pretty much why they were going to spend that much money.  These days, however, the decision to purchase a half-decent scope almost rates as much as choosing to put Premium fuel into your car instead of regular.


In addition to the Where and Why, is the How - and this is just as important.  As well as being shown the way to set up a measurement, being told about how parasitic capacitance can affect a measurement provides the practical knowledge in an explicit statement.  The specification of the probe may have this information, but a user needs to be told how that information is used in practice.  Until then, they may not know why the specification is even there.


I think the OP's idea has its merits.
 
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Offline james_s

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Re: Beginners Guide to Digital Oscilloscope
« Reply #5 on: March 15, 2017, 04:48:23 am »
I think that's the ticket, walk a user through actually *using* each feature, or at least the more important ones. At one point I didn't really "get" digital scopes, then the EE we had at one place I worked sat me down in front of one and showed me how to capture some waveforms and very quickly it made perfect sense. More recently when I got an old logic analyzer I found the HP training guide for it and sat down to work through the exercises, substituting one of my FPGA boards for the hardware that would have come with the training kit and that was a very effective way to become proficient at using it. Reading the manual explains each feature but knowing what the feature does and knowing how to use it in practice are often not the same thing.
 
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Offline tautech

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Re: Beginners Guide to Digital Oscilloscope
« Reply #6 on: March 15, 2017, 06:37:32 am »
I'd hope anyone that writes a DSO beginners guide learnt their craft on a CRO, that way the features a DSO offers become emphasised over CRO's and then one can truly point them out to the uninitiated.
Basic CRO understanding is a very valuable prerequisite to using a DSO, not a deal breaker but none the less, valuable.

Good luck OP, we'll mark your contribution.  >:D
Take your time, to get it right won't take just five minutes.
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Offline james_s

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Re: Beginners Guide to Digital Oscilloscope
« Reply #7 on: March 15, 2017, 07:46:35 am »
Yeah I always recommend beginners start with an analog scope. It's a bit like learning how to fly the plane before you start using the fancy autopilot system. An analog scope forces you to understand what you're actually doing and then later the DSO makes many of those tasks faster, easier and more accurate.
 

Offline jacklee

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Re: Beginners Guide to Digital Oscilloscope
« Reply #8 on: March 15, 2017, 08:51:17 am »
Thank you for all of your kindness reply here, I'm going to write is really basic things about oscilloscope, it's totally for absolute newbies. For the limition of my knowledage, there's must be something rather need improve. I'll update one chapter everyday from basic to advance. Hope you like it.  :)
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Offline jacklee

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Re: Beginners Guide to Digital Oscilloscope
« Reply #9 on: March 15, 2017, 09:37:45 am »
Preface
This posts seeks to summarize the general rules of the oscilloscope from the numerous brands and models. After read this posts, I hope readers can handle the most digital oscilloscope.

The scope of this post does not cover large desktop oscilloscope. This post is divided into two parts: basic parts and advanced parts. By learning the basics, you will have a basic understanding of the using of oscilloscopes, and the majority of common signals to debugging, display, and some quick automatic measurements. After learning the advanced parts, the use of the oscilloscope will have a more profound understanding. For the signal can debugging, preservation, analysis etc.

Basic Parts
Chapter 1 Types of oscilloscope

The common oscilloscopes has desktop oscilloscopes (this post does not cover the use of methods), portable oscilloscopes, handheld oscilloscopes and tablet oscilloscopes.

1)Desktop oscilloscope


2)Portable oscilloscope


3)Handheld Oscilloscope


4)Tablet Oscilloscope
As the name suggests, tablet oscilloscope is no buttons and knobs, using full touch operation.
« Last Edit: March 16, 2017, 09:40:13 am by jacklee »
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Offline tooki

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Re: Beginners Guide to Digital Oscilloscope
« Reply #10 on: March 15, 2017, 12:15:26 pm »
I'd leave a comparison of scope types for the end. Since most of what differentiates them is in details -- details that won't be covered until later -- it means the introduction chapter will be comparing things the reader doesn't know yet.
 

Offline guenthert

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Re: Beginners Guide to Digital Oscilloscope
« Reply #11 on: March 15, 2017, 05:04:47 pm »
Yeah I always recommend beginners start with an analog scope. It's a bit like learning how to fly the plane before you start using the fancy autopilot system. An analog scope forces you to understand what you're actually doing and then later the DSO makes many of those tasks faster, easier and more accurate.
Lets face it, analogue oscilloscopes are a 20th century artifact (*).  Some old timers have a difficult time with the transition and lament the absence of this and that feature their high end CRO offered decades ago and now missing on entry level digital oscilloscopes.  Not sure, whether there is real benefit in burden newcomers with that.

Quite some effort has been put into making electron beams reflect a given signal, with some amazing results, but lets not forget that it's just a means, not an end itself (except for collectors of antiques).
  Whenever extra-sensory signals are transformed to allow humans to perceive them, some compromises have to be made.  CROs make different compromises (and compromise they do!) than digital oscilloscopes.  I think the latter are held back by the market expectations formed by the former.  It's perhaps comparable to film vs. digital cameras.  For a long time professional digital cameras used a mirror like the analog forefathers (often even the same body, just with a sensor placed where the film used to be).  Cheap consumer cameras dumped the superfluous (**) mirror long ago, which then absurdly became a differentiator welcomed by the marketing folks.  Only lately one finds high-end photo cameras without mirror.
  Likewise I'd like digital oscilloscopes freed from the clutches (and crutches) of the Xray generating past (***).

And yes, in the beginning, the quality of the output of digital cameras was no-where near the one of film cameras, still they won, chiefly because they were good enough for the dominating use case (on-line photo sharing rather than poster-size prints) and their outstanding convenience and instant gratification. 
  The killer feature for oscilloscopes is the 'single shot' data acquisition.  Yes, for reasonable quick signals it is possible in an inconvenient, time consuming and very limited sense with CROs (+ camera), but only digital storage made it accessible to most.
  Digital oscilloscopes wooing consumers used to operate CROs mimic their user interface.  But oscilloscopes aren't cars, a break in the user interface isn't a safety risk.  New users are more likely to tinker with Arduinos and similar MCUs, than repairing TVs.  They won't be averse of having a computer on their bench, in fact, their desk might be their bench.  USB based (fast) data acquisition systems with protocol analyzer might be better suited to their needs than a 'bench' oscilloscope with knobs.  Then the detour via CROs becomes even more questionable.

just my 2c
(I do use a CRO on my bench, chiefly because it has no fan, but for serious trouble shooting I use my DS1054z, for 'exploratory' tinkering, I actually prefer my Analogue Discovery, as it allows me to use a big screen, its 14bit ADC - so I can use it as signal and network analyzer - and the lack of a fan)


*) I am aware that there are some moderately fast CROs cheaply available on the second-hand market (e.g. TEK475) , which only quite expensive digital oscilloscopes can match, but I don't think there has been any new CROs developed in this millenia other than low bandwidth (<25MHz) models at rock-bottom price for the educational market and low income markets

**) Early electronic displays didn't offer the contrast or low latency professional users demanded, hence the optical viewfinder (necessitating a mirror or prism) remained (remains?) popular with that group for a long time.  Further early sensors were self-heating during continuous use, which increased noise.  Recent sensors allow fast, lower resolution modes with limited self-heating.
 
***) It's difficult to change the deflection of an electron beam greatly very rapidly, hence the CRTs used in CRO tend to be quite narrow and comparatively long.  There was no easy way around it, so small screens became accepted by the market, but why should digital oscilloscopes be limited to a 7" screen?  Even professional CROs offered often an uncertainty no better than 3%, which then resulted in digital oscilloscopes getting away with 8bit ADCs (whether higher accuracy is a valuable feature in an oscilloscope might not be so clear, but a higher resolution would allow for a more sensible FFT feature).
« Last Edit: March 15, 2017, 05:08:38 pm by guenthert »
 
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Offline james_s

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Re: Beginners Guide to Digital Oscilloscope
« Reply #12 on: March 15, 2017, 07:50:13 pm »
I'm not arguing against the fact that analog CROs are for the most part obsolete, however there is much that can be learned by using one and for me anyway I found it a lot easier to grasp the concept when I could see it happening in real time. I mean turn down the sweep to where you can watch the spot scanning and then vary the input voltage, you can actually see the scope drawing the waveform. I would argue that a good analog CRO is in most ways superior to a cheap hobby DSO, you can get 100MHz+ with dual channels, delayed sweep and other features for about the price of a 2MHz or less toy DSO.

Likewise it could be argued that a manual gearbox in a car is obsolete, but I'm still of the opinion that one should learn to operate one, along with having some basic mechanical understanding of how a car works makes one a better driver.
 

Offline hurricanehenry

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Re: Beginners Guide to Digital Oscilloscope
« Reply #13 on: March 15, 2017, 09:40:37 pm »
You don't ACTUALLY need to store any data with a DSO.

You can just switch to observing the trace in real-time, just like a CRT scope.

And if you ignore all the fancy digital features, and just focus (no pun intended) on the scales and positions knobs, it's pretty much the same as a CRT scope. (You can configure down the sample rate and resolution also, to simulate the low resolution of the CRT).

So, no need to really use a physical CRT scope. Just force yourself to stick to the basics.

I mean, after all, it's really just a way to display the voltage level, over time, on a screen, so you can visualize it, unlike looking at the digits on a DMM (someone with super human memory might be able to look at DMM digits and in his or her mind, graph it!)
 

Offline james_s

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Re: Beginners Guide to Digital Oscilloscope
« Reply #14 on: March 15, 2017, 09:55:00 pm »
No, you don't *need* to physically use a CRO, but I still say there is value in doing so, especially when they can be had so cheaply. I have both, I use both, since getting a TDS784C I have relegated by beloved 465B to the lesser used closet but prior to this I had a lower end DSO and preferred to use the analog 465B for most things. Even with the TDS, it's not quite the same, it doesn't have that real, physical feel of an analog CRO, there is a noticeable abstraction layer. Despite all of the amazing things it can do, the TDS still does a rather poor job of emulating the velocity modulation you get with a CRO. Once you become proficient in using an analog CRO to view waveforms and take measurements, transitioning to a DSO is easy.
 

Offline DimitriP

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Re: Beginners Guide to Digital Oscilloscope
« Reply #15 on: March 15, 2017, 10:04:49 pm »
Quote
in real-time, just like a CRT scope

Really close , almost real time but not exactly...
A digital scope will have a perceptible,  if not inconsequential delay.

https://youtu.be/GerxUs3gfls?t=291



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Offline rstofer

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Re: Beginners Guide to Digital Oscilloscope
« Reply #16 on: March 16, 2017, 12:06:41 am »
Besides the User Manual, there is an epic thread in the stickies above and then there is the Tektronix material using an Arduino:
http://www.tek.com/lab-course/learn-digital-oscilloscope-operations-using-arduino-board-dut-signal-generator

And hundreds of YouTube videos (I suspect).
 

Offline hurricanehenry

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Re: Beginners Guide to Digital Oscilloscope
« Reply #17 on: March 16, 2017, 01:19:04 am »
I would love to also have a good classic CRT scope.

However, even if I can come up with the extra dollars for it, which won't be too much, I can't come up with the extra desk space for it, which will be way too much.

:-D
 
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Online Brumby

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Re: Beginners Guide to Digital Oscilloscope
« Reply #18 on: March 16, 2017, 01:38:09 am »
I'm not arguing against the fact that analog CROs are for the most part obsolete, however there is much that can be learned by using one and for me anyway I found it a lot easier to grasp the concept when I could see it happening in real time. I mean turn down the sweep to where you can watch the spot scanning and then vary the input voltage, you can actually see the scope drawing the waveform.

This also appeals to me.

In addition, while the DSO may have a number of added value functions, the basics are still derived from the analogue era.  These basics are still used - perhaps because they are familiar, but more importantly is because they work.  Seeing them working on a CRO and they fall into place, helping one's understanding of how these devices worked and evolved.

Well - to me, anyway.
 

Offline tautech

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Re: Beginners Guide to Digital Oscilloscope
« Reply #19 on: March 16, 2017, 04:27:52 am »
I'm not arguing against the fact that analog CROs are for the most part obsolete, however there is much that can be learned by using one and for me anyway I found it a lot easier to grasp the concept when I could see it happening in real time. I mean turn down the sweep to where you can watch the spot scanning and then vary the input voltage, you can actually see the scope drawing the waveform.

This also appeals to me.

In addition, while the DSO may have a number of added value functions, the basics are still derived from the analogue era.  These basics are still used - perhaps because they are familiar, but more importantly is because they work.  Seeing them working on a CRO and they fall into place, helping one's understanding of how these devices worked and evolved.

Well - to me, anyway.
Agreed.
Every now and then when in a hurry I use one of those value added functions: Autoset  ::) only then to hit the "Undo" that Siglent's thankfully have and then proceed to do the job properly as I should've from the start. Grrr.
Much prefer to drive my scopes.  :) (learnt from CRO days)
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Offline rstofer

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Re: Beginners Guide to Digital Oscilloscope
« Reply #20 on: March 16, 2017, 05:32:28 am »
I would love to also have a good classic CRT scope.

However, even if I can come up with the extra dollars for it, which won't be too much, I can't come up with the extra desk space for it, which will be way too much.

:-D

I have a Tek 485 and I leave it standing up on the floor - usually under my bench.  I just slide it out a bit when I want to use it.
 

Offline jacklee

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Re: Beginners Guide to Digital Oscilloscope
« Reply #21 on: March 16, 2017, 09:45:45 am »
Chapter 2 Probe

The picture below shows our commonly used probe and its accessories.



Probe tips: While test signal, try to use short ground wire and grounding point close to the signal as far as possible, or the observed signal may distortion. The higher the frequency of the signal, the more distortion occurs.

The following figure shows the effect of the length of the ground to the measure results:


An actual rising edge signal (signal source connected directly to the oscilloscope, no probe?


Measuring the rising edge signal with long ground wire


Measuring the rising edge signal with grounding spring needle
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Offline danadak

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Re: Beginners Guide to Digital Oscilloscope
« Reply #22 on: March 16, 2017, 11:08:52 am »
An analog scope still quite useful, especially the frame type that accept
specialized plugins. Like high performance diff amp, fet input, various
samplers to 10 Ghz, continuous real time out to 1 Ghz, semiconductor
curve tracing, logic analyzer, time bases down to 200 psec..., multimeter,
tdr (down to 25 psec head), spectrum analyzer to 18 Ghz........

Tektronix 7000 series, obsolete, but still available used market. Several
7000 mainframes, 7854 UP controlled, 7104 1 Ghz, 7834 storage, 7844
dual beam........

http://www.tek.com/Measurement/Support/scopes/faq/history.html

http://w140.com/tekwiki/wiki/7000-series_plug-ins

http://w140.com/tekwiki/wiki/7000-series_scopes


Regards, Dana.
« Last Edit: March 16, 2017, 11:10:51 am by danadak »
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Offline jacklee

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Re: Beginners Guide to Digital Oscilloscope
« Reply #23 on: March 17, 2017, 09:55:31 am »
Chapter 3 Test a signal

Oscilloscopes typically will output a 1 KHz, 5 V (or less) square wave signal, which is used as a probe head calibration compensation. This signal is usually marked with a square wave sign plus a ground symbol. We can use this signal as the signal source.



Open oscilloscope and connect the BNC of prove to channel 1 as below figure shows. The other end connect to the square wave signal output port



Press the "Auto Setup " button (usually marked  "Autoset " or "Auto " on the oscilloscope ).



After automatic set the oscilloscope can get a stable waveform, as below shows



Tap the "AUTO " key, the oscilloscope can automatically adjust the vertical, horizontal trigger settings according to the input signal to make the waveform display moderately and easy to observe.
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Offline Avacee

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Re: Beginners Guide to Digital Oscilloscope
« Reply #24 on: March 17, 2017, 10:10:44 am »
A user manual is just going to show you what the feature is and its specifications - and how to find in on multi-level menu setups.
What it won't show you is where you would use it and why.  These are rather important for absolute newbies, which is what the price/performance trend is allowing more and more.

As a young player this is exactly what I'm constantly googling for - as well as "traps for young players".
Where, Why and How, and WhatNotToDo are sadly lacking in so many "tutorials" which are mostly Puff Pieces where people say "do this". They don't educate people on what to do if you don't get the same result as what Mr Puff Piece got or help people spot what they've done wrong.

The "why" and "traps for young players" are why I love Dave's video's so much.
Case in point: EEVblog #652 - Oscilloscope & Function Generator Measurement Trap  .. Dave goes into massive detail on what NOT to do with practical demonstrations as to why not. Viewers will have learnt far more from what not to do compared to a 3 min video or a few slides of someone saying "do this". Now, if they get a similar wrong result they'll know why its wrong and what to do to correct it and just as importantly, how to not repeat the mistake.

Fantastic idea with great merit and many young players like me would definitely appreciate it but if you just rehash the manual/existing tutorials what extra value have you created with your time and effort?
« Last Edit: March 17, 2017, 10:18:06 am by Avacee »
 


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