Monday, September 17, 2012

Overview of Oscilloscope Triggering

In this post we will take a look at Oscilloscope triggering. We will cover the basics and look at some of the advanced triggering capabilities found in modern digital scopes. Triggering is often the least understood but one the most important capabilities of a scope. You can think of oscilloscope triggering as “synchronized picture taking”. And one waveform picture actually consists of many individual and consecutive digitized samples. When monitoring a repetitive input signal the oscilloscope performs repetitive acquisitions (or repetitive picture taking) to show a “live” picture of your input signal. This repetitive picture taking of the oscilloscope must be synchronized to a unique point on the input signal in order to show a stable waveform on the scope’s display.

Although some scopes have various advanced triggering modes to choose from, the most common type of triggering is to trigger the scope when the input signal crosses a particular voltage threshold level in either a positive or negative direction. We call this “edge triggering”. In other words, the scope triggers (takes pictures) when the input signal changes from a lower voltage level to a higher voltage level (rising edge trigger) or when the input signal changes from a higher voltage level to a lower voltage level (falling edge trigger). A photo finish of a horse race is analogous to oscilloscope triggering. To accurately record the finish of the race, the camera’s shutter must be synchronized to when the lead horse’s nose crosses the finish line in the forward direction.

Edge Triggering Examples
Let's look at two examples of oscilloscope edge triggering. In the screen-shot below, the scope’s trigger level is set above the waveform. In this case the input signal never crosses the trigger threshold level in any direction. The scope is taking asynchronous pictures of the input signal and we observe what appears to be an unstable waveform. This is actually an example of not triggering – or unsynchronized picture taking.

Untriggered (unsync'd picture taking)
In the below screen-shot, the scope is setup to trigger on rising edges of the input signal with the trigger level set at +2.01 V. In this case, we can see a rising edge of the input signal at exactly center-screen. 

Triggering on Rising Edge @ +2.01 V
Although the default trigger localization on all digital oscilloscopes is at center-screen (horizontally), you can re-position the trigger location to the left or right by adjusting the horizontal delay knob – sometimes called the horizontal position knob. Older technology analog scopes are only able to trigger at the left side of the screen. This means that analog oscilloscopes are only capable of showing portions of waveforms that occur after the trigger event – sometimes called “positive time data”. But DSOs are able to show portions of waveforms both before (negative time or pre-trigger data) and after (positive time data) the trigger event. Observing pre-trigger data can be useful for analyzing waveform data that may have led up to a specific error trigger condition.

Edge triggering is by far the most common method used for scope triggering. Modern digital scopes also include many advanced triggering methods such as Pulse Width, Pattern, and Runt. Let's take a quick look at a few advanced triggering methods in modern scopes.

Advanced Oscilloscope Triggering – Rise/Fall Time
The below screen shot is an example of signal parametric violation triggering. In this case we are showing an example of triggering on a rising edge that fails to meet a specified rise time of 100 ns. This scope can also trigger on falling edge violations, as well as edge speeds that are faster than a user-specified time.

Triggering on rising edges if slower than 100 ns
Advanced Oscilloscope Triggering – Setup & Hold Time
In the below screen-shot we showing an example of a setup & hold time violation. The scope has been setup to trigger on a rising edge of a clock signal (channel-1, yellow trace). The green trace shows the channel-2 waveform, which is a data signal represented as an eye-diagram. When writing data into a storage device, shift register, or latch, the data signal must be stable for a minimum amount of time before the arrival of the clock signal. This is called “setup time”. In addition, the data signal must remain stable (high or low) for a minimum specified time. This is known as “hold time”. 

Edge Triggering Reveals Data Edge Shift
In this particular example we can see that the data signal occasionally shifts in the positive time direction closer to the clock edge. We know that it is an occasional or infrequent timing shift as evidenced by the dimmer intensity of the trace (assuming that the scope has waveform intensity gradation capability). This is a violation of the device’s setup time.

In this post we looked at oscilloscope triggering, from basic to advanced. If you have anything to add to this post use the "Comments" section below and if you have any questions send me an email.


  1. شركات نقل العفش بالدمام نقل عفش بالدمام نقل اثاث بالدمام شركة نقل عفش بالمدينة المنورة شركة تنظيف خزانات بجدة

  2. شركة نقل عفش بجدة شركة نقل عفش بالرياض شركة تنظيف بالطائف شركة تنظيف خزانات بالمدينة المنورة

  3. Oscilloscope is an electronic machine used to describe the voltage of an electronic machine. best oscilloscope

  4. Seems like you need to look here for some information on how to write interesting essay. And also some good conclusion to your essay. Take a look by yourself

  5. There are very many pages that I have been to, however one thing that I can attest to is the fact that this proves to be rather too informative. The overview of oscilloscope triggering was very new to me until I came across this post. Great work. When you are out to look for the most reliable editing help, petrian editing services, are just a mouse click away. We do offer the best assistance.

  6. There is an extensive rundown of brand names that you can browse in view of moderateness. check these guys out

  7. Sometimes the retailers impose selling trick for high-priced accessories, which hardly has any utility function in the operating function of the main gadget. Bobsweep

  8. Now and again the retailers force offering trap for expensive extras, which scarcely has any utility capacity in the working capacity of the fundamental contraption. top refrigerators in india

  9. With the majority of your system companions who can without much of a stretch view transferred pictures, computerized cameras have turned into a hit notwithstanding for the youthful clients.Bobsweep robotic vacuum cleaner review

  10. Electronic Products are clear impressions of our modernization. The utilization of electronic items is massively spreading around the world.Bobsweep pethair plus reviews

  11. Thank you for your sharing. Thanks to this article I can learn more things. Expand your knowledge and abilities. Actually the article is very practical. Thank you!
    subway surfers

  12. SEO Friendly team digital marketing services Illinois are tailored to the unique needs of each audience and brand objective, ensuring improved sales growth a profit. You can top rank website marketing for specialized marketing consulting services that include: SMO, PPC, Email Marketing, website design, SEO, Typing work, content writing marketing etc. We offer complete packages of efficient digital marketing services New York that adapt to fit your company needs. Click hers to see how we can help you(Related keyword for this services:- top Digital Marketing Services in Illinois, best online marketing company Connecticut, faster Internet marketing agency Palos Heights, businesses promotion firm Kewanee, marketing solutions provide advertisers Winnetka, Lincolnwood, business promotion Markham, effectively digital company Centralia, experience agency Pflugerville, digital advertising organization Rowlett, San Marcos)

    Visit us for more info- Digital marketing services in Illinois
    SEO Services in Illinois
    PPC Services in Illinois
    SMO services in Illinois
    Web design services in Illinois
    Lead Generate services in Illinois
    Email Marketing Services in Illinois
    web development Services in Illinois
    Contact Writing Services in Illinois

  13. SEO is a critical component of internet marketing. At SEO friendly team we use a combination of the latest onsite and offsite strategies to produce top results. There are a variety of SEO services Illinois which offer for ranking issues and website traffic. Depending on your goal and needs one or a combination of the below for this services may be right for your website. SEO services in Illinois at a affordable prices. Contact us today. (SFT provider of this services:- SFT provider of this services Top SEO Services Company in Illinois, Affordable SEO services Connecticut, SEO Packages in Palos Heights, search engine optimization Services Kewanee, Create a traffic on website in Winnetka, Increase website ranking Lincolnwood, Experienced SEO services provider Markham, Best Leading SEO agency Jewett City, Multilingual and International SEO Danielson, Google update Groton, First page of search engine in Derby, White hat, Off page, On page)

    Visit us for more info- Typing Work Services in Illinois
    Digital marketing services in Pennsylvania
    SEO Services in Pennsylvania
    PPC Services in Pennsylvania
    SMO services in Pennsylvania
    Web design services in Pennsylvania
    Lead Generate services in Pennsylvania
    Email Marketing Services in Pennsylvania
    web development Services in Pennsylvania


  14. The application form of SSC MTS will be released in December 2018. Earlier, the application form was scheduled to be released on November 3, 2018 and the last date to apply was December 3. However, the application process has been delayed till further notice. Candidates will have to fill SSC MTS Application Form 2019 online.

  15. Programming Assignment help
    Programming Assignment Help is efficient in reducing stress from your academic life. It can save most of your time. Hence you can utilize your time in other necessary works. However, it is essential to choose a proper service; else it can trouble you badly. To avoid this, you must check the online reviews for a better Computer Science assignment

  16. Avail the best Assignments Helper services in Australia by top rated experts at cheapest prices at MyAssignmenthelp most trusted online assignment writing company provides the assignment writing help service for students in Australia of all levels, starting from high school till Ph.D. Our professional academic assignment helper prepares custom written assignment exclusively for you to achieve A+ grade.

  17. The choice of battery or sun oriented fueled cameras, can include significantly greater adaptability, as all that would be required, is the remote association with the system. Witty Spy

  18. Use a steam cleaner to get dirt, grime, bird poop etc. off of patio furniture. You can even use it on upholstered patio furniture and umbrellas.

  19. It is very interesting and informative post. Thanks for sharing.
    Risk Management Assignment Help offers efficient assignment writing for risk management students.

  20. Another innovation include that went along to compliment the movement initiated highlights of concealed cameras was the expanding fame of the DVR, which in the end everything except supplanted the VCR. Cassy

  21. This is great innovation of oscilloscope triggering, thanks for sharing the information.
    Statistics assignment help

  22. i have read your blog. you post gave me a new perspective. if you want hire professional writer . then provide you essay writing service . we have many experts. Those have analytics knowledge in essay writing. you can just send an email

  23. you can go through reviews. It will help you to know about the services, and it will help you to know whether that site is reliable or not. This is a way of understanding the opinion of users, and it helps the website to maintain its functionality and reliability.

  24. This comment has been removed by the author.

  25. It is nice to read such high-quality content. It is a good article that discusses the topic at hand quite well. I am looking forward to read more articles from your site. Keep up the good work.
    assignment expert

  26. The most well-known model would be a remote control gadget, which makes it simpler to change tracks, alter volume and so on without contacting the support. affordable used cars

  27. Nice Post Please Keep Posting Like This. I am really happy that you guys are writing content like this. Please Keep Posting on Regular Basis.
    Best Refrigerator In India
    Double Door Refrigerator In India

  28. Pay extremely low prices for Assignment help Singapore offered by

  29. To ease services,we avail web portal for write my research paper online services where Australian students make “write my essay” “write my research paper” and “write my paper” requests.

  30. Very informative article really love the way you write. worth visiting as well as worth recommending to the people.Thanks to you for sharing this helpful information with us.keep going.|Nano Education

  31. This comment has been removed by the author.

  32. Hi! Thanks for sharing this kind of information it's really nice. If anyone need and if you Buy Assignment Online for students and you don't know how to get the high-quality assignment help? Now don’t worry MyAssignmentHelpAu providing best Assignment Help. You have simply contact our expert team we have available 24*7. Also visited our website