Oscilloscope ADC Bits and ENOB - Exposing Signal Integrity Myths - E1
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- čas přidán 25. 03. 2019
- Learn why you should care about effective number of bits (ENOB)
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Understanding the difference between number of ADC bits and the effective number of those bits is critical if you are trying to make the most accurate measurements possible. An oscilloscope can be specified to a certain number of ADC bits, but do you know whether all of those bits are effective in making your measurements?
In this episode of Exposing Signal Integrity Myths, you will first learn about why you should care about ADC bits and what they mean for your signal. The more bits there are, the more quantization levels there can be, which ultimately means more signal detail.
By the end of the episode, you will understand why the effective number of bits (ENOB) specification is just as important as the number of ADC bits. You should always be considering ENOB when you are evaluating the measurement quality of an oscilloscope.
Tune in for future Exposing Signal Integrity Myths episodes covering more common misconceptions around signal integrity!
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The mixed signal oscilloscope we used:
www.keysight.com/en/pcx-x20521...
(The Keysight Infiniium S-Series Oscilloscope)
The S-Series allows you to see the truest representation of your signal with the industry’s best signal integrity: 10-bit ADC, low noise front end, superior time base, signal processing in hardware, and responsive deep memory.
Exposing Signal Integrity Myths is hosted by Erin East. The video series dives into various misconceptions around oscilloscope signal integrity. In watching this series, you will learn about the important considerations for determining an oscilloscope’s true measurement quality. Understanding the system as a whole will give you visibility into the true performance of your device.
#ADCbit #SignalIntegrity #ExposingSignalIntegrityMyths #Oscilloscope #HowTo #Engineering #ElectricalEngineering #Tutorial #Basics #Electronics #ElectricalEngineers #scopespecs #oscilloscopespecs #scopespecifiations #oscilloscopespecification - Věda a technologie
Nice Explanation 👍
I believe these videos will have been displayed in many students from their teachers.... especially at the quarantine period will save the day.
This is actual not only for the oscilloscopes, but for any ADC job. :) LSB, usually is very noisy. In my audio system i need to ignore one LSB and write special algorithm in Atmel mcu firmware for audio level indicator to filter out noise and remove low level indication jumping.. After that all was ok, now, at least 6 years.. ADC is separate ADC chip, not integrated, clocked from Atmel's OC pin, still there from first version time (without AVR), for compatibility..
Similar situation in other projects when using integrated ADC, example, for battery monitoring - firmware noise filtering and in some cases shifting out LSB..
Anyway, great, actual video which explains more wider common ADC problem, that can be find not only in oscilloscopes!
Absolutely!
very good and concise video! thank you for posting.
Great video!
Maybe you could explain why XY mode on older analog based oscilloscopes is so much better than on digital oscilloscopes. Such as going into the details on how the ADC digitization is not as good as the cathode ray tube's output. This topic would fit in well after this video too!
And as Helmut stated down in the comments, I also would appreciate more quantifiable values and equations associated with ENOB and your other topics. Like what would be considered a good typical ENOB? I already know though from my wireless communications EET course.
From my observations with a hybrid analog/digital combiscope, It seems that the bit depth is the least of the worries. When I am able to get a solid capture of an atari vector game, the signal looks fine with the 8-bit digital mode. However, displaying an active game is trash on digital and beautiful on analog. I believe this is because of the fact that the digital display can only update at a certain rate (Usually with no consideration to the input signal), artificial / no persistance, and other emulated features that try to match the performance of a true vectorscope or analog x-y scope.
Well isn't that a coincidence. I was just looking up ENOB literally 2 days ago and found out that each test equipment manufacturer measures ENOB a bit differently. This sure explains why. Thanks!
Yeah! It's a deep dive to be sure. This is just scratching the surface!
Hi Erin.
Can you please make a video about the DSOXEDK you could follow the "Keysight Advanced
Training Guide" and expanding some of the topics?
This will make a nice intro to (Keysight) osciloscopes in EE teaching?
JFG
How about a ENOB video for Spectrum Analzyers ? Also a real time vs swept time spectrum analyzsis
of basic sinusoidal FM modulation ? Does the instantaneous frequency variation turn each little sideband
off and on like light bulbs intermittently ?
Lovely video! ADCs are such deep subject matter its insane!. Just an idea can you look at more videos incorporating Bnechvue, is it possible to allow Benchvue to stream and capture decoded serial packets and then later save it for further analysis offline.
@MichaelKingsfordGray hahha corrected.
This video was helpful for bringing to my attention the importance of system ENOB because I'm looking for a new entry level scope. However, when I went to look for system ENOB specs for Keysight scopes, I couldn't find any listed. I understand that system ENOB may be more relevant than ADC bits, but if Keysight doesn't publish this information how is a prospective buyer supposed to use it in the purchase process?
When u wil do the next scope giveaway??
Some noise is critical for dithering (e.g. in hi-res or averaging modes). IIRC, one wants at least one bit of noise.
That's a good point! Scopes often do some intentional dithering to avoid aliasing. Here's an old patent on it: patents.google.com/patent/US5115189
I still don't know, how System ENOB is defined, or what it all includes. Please simply show one chart with the mathematical definition, or the calculation with all possible influencing variables. Also missing is a concrete example, how KS scopes perform in practice in this aspect. All that would have made your explanations much more transparent, understandable, and less laborious. Please take these hints into consideration for your future videos.
PS: The linked brochure about scope SI is likewise unspecific and qualitative only.. HEY! Here on the other side of the screen are many engineers and scientists..
PPS: And I'm missing the good old 'Theory of Operation', i.e. these great manuals and Application Notes from the 60ties to 80ties, explaining such things in depth.
video is good but add equations and some mathematics
Zigbee
As designing any resistive circuit is very easy but how can a R-C , R-L , R-L-C , circuits are designed . That has very complex design and have a huge amount of R,L,C interconnected .
Please do not use the terms accuracy and precision interchangeably. NOB and ENOB speak to precision while accuracy should actually be based on some sort of standard. This makes a difference. Thanks.
I didn't win a thing during the "Great Keysight Test Equipment Giveaway" and now I will not buy a single item of Keysight equipment.
So there!
hate the background music. I willl no longer sub or watch channels that has background music.
The whole lecture's a little lame, why not make it more praxis relevant with examples and bring the values, e.g.: ENOB, bits, levels, vertical scale in relation to each other on a peace of paper or whiteboard and than do a measurement of a test signal showing the effective ENOB’s. Should not be so difficult. Regards Helmut
I am watching this kind of videos to learn something and to get motivated to get into it further, but this video series does not make it right. A few examples how to bring the messages via videos to users are: Andreas Spiess, w2aew, The Signal Path, EEVblog, or even a very basic convincing video trainings like “Der Hobbyelektroniker”. Ok Keysight must not be this good, however better that what they got.
Keysight has very fine products, I own for my hobby bench a new Keysight DMM and power supply as well as older devices like frequency counter and waveform generators and spectrum analyzers.
For me I start often with basic devices and at some point I switched to precision devices, often from Keysight. The the deal must be to get peoples attention first and later they purchase when the requirements occurs.