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    The Trainer #155: Scope Sample Rate vs. Buffer Size

    Dec. 10, 2024
    Optimizing scope capture capability means choosing a sample rate that allows for glitch capture, an accurate picture and plenty of stored data to view

    He’s back! Technical Editor, Brandon Steckler, with another golden nugget from the trenches of automotive diagnostics. This time, one of the most overlooked aspects of digital storage oscilloscope (or DSO) implementation is scope sample rate.

    Although there are many important aspects to selecting the scope that is right for you and your shop, one of the most important is scope sample rate. A scope (like many other circuit measuring devices) is one that takes samples (like photos from a camera) and plots them on a graph (the domain you’ve chosen to measure in, over a period of time selected). Sample rate refers to the scopes ability to capture data and is reflected in a rate of “samples per second.” What many technicians fail to realize is that the scope sample rate diminishes as you request the scope to perform more work. This is best described by way of example:

    Suppose a scope is capable (at its fastest) of capturing data at a rate of 1,000,000 samples per second (1Ms/sec). If this scope is equipped with (and is using) four channels, the sample rate is split between the channels (due to a common scope construction and design). So, the 1Ms/sec becomes only 250,000 samples per second (or 250ks/sec). If the scope utilizes eight channels, this characteristic becomes worse (1Ms/sec becomes 125ks/sec). Again, each time another channel is utilized the sample rate is split again.

    Furthermore, the more time that is captured (large time base vs. small time base) the more this characteristic can limit the scope’s sample rate capture capability. With that, a perfectly healthy signal can be so deficient of sample rate, it can lead to a misdiagnosis; That is the trade-off.

    The point? We must always understand the limitation of the tool we choose to implement. Optimizing the scope’s capture capability means balancing sample rate with buffer size (the size of the scope’s data storage tank).

    All scopes (and other tools) have limitations, no matter how popular or expensive they might be. Taking the time to identify these limitations is the difference between a “homerun” vs a “swing-and-a miss.”

    Stick with master diagnostician, Brandon Steckler and learn what it means to discover sample rate limitations to maintain your accuracy and boost efficiency, on this episode of The Trainer!

     

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    Due to factors beyond the control of Endeavor Business Media, it cannot guarantee against unauthorized modifications of this information or improper use of this information. Endeavor Business Media assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. Endeavor Business Media recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of Endeavor Business Media, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage, or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not Endeavor Business Media.

    The tool and/or equipment featured in this video was supplied by the manufacturer and may or may not be retained by the reviewer at no cost.

    About the Author

    Brandon Steckler | Technical Editor | Motor Age

    Brandon began his career in Northampton County Community College in Bethlehem, Pennsylvania, where he was a student of GM’s Automotive Service Educational program. In 2001, he graduated top of his class and earned the GM Leadership award for his efforts. He later began working as a technician at a Saturn dealership in Reading, Pennsylvania, where he quickly attained Master Technician status. He later transitioned to working with Hondas, where he aggressively worked to attain another Master Technician status.

    Always having a passion for a full understanding of system/component functionality, he rapidly earned a reputation for deciphering strange failures at an efficient pace and became known as an information specialist among the staff and peers at the dealership. In search of new challenges, he transitioned away from the dealership and to the independent world, where he specialized in diagnostics and driveability. 

    Today, he is an instructor with both Carquest Technical Institute and Worldpac Training Institute. Along with beta testing for Automotive Test Solutions, he develops curriculum/submits case studies for educational purposes. Through Steckler Automotive Technical Services, LLC., Brandon also provides telephone and live technical support, as well as private training, for technicians all across the world.

    Brandon holds ASE certifications A1-A9 as well as C1 (Service Consultant). He is certified as an Advanced Level Specialist in L1 (Advanced Engine Performance), L2 (Advanced Diesel Engine Performance), L3 (Hybrid/EV Specialist), L4 (ADAS) and xEV-Level 2 (Technician electrical safety).

    He contributes weekly to Facebook automotive chat groups, has authored several books and classes, and truly enjoys traveling across the globe to help other technicians attain a level of understanding that will serve them well throughout their careers.  

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