What's The Point Of A 'High Definition' Oscilloscope? i.g. 12-bit ADC - Page 1
Forum section: electronics / testgear

author: nbritton
author_rank: Frequent Contributor
timestamp: September 18, 2015, 05:11:01 am
content: Teledyne LeCroy is marketing its HDO4000 with a 12-bit ADC, however, the vertical resolution on their LCD screen is 800 pixels. What's the point of 2^12 (4096) levels when you're limited to 800 pixels on the screen?

author: radhaz
author_rank: Regular Contributor
timestamp: September 18, 2015, 05:17:45 am
content: I'm guessing data acquisition.

author: BradC
author_rank: Super Contributor
timestamp: September 18, 2015, 05:19:58 am
content: Quote from: nbritton on September 18, 2015, 05:11:01 amZoom.

author: TMM
author_rank: Frequent Contributor
timestamp: September 18, 2015, 05:46:19 am
content: The FFT function will also have a lower noise floor.

author: KedasProbe
author_rank: Frequent Contributor
timestamp: September 18, 2015, 07:06:35 am
content: More Points!(couldn't resist)But yes it would help if they also increased the Display resolution, waiting for a Full HD scope for a nice price... (with HDMI out)

author: wiss
author_rank: Frequent Contributor
timestamp: September 18, 2015, 07:54:57 am
content: DAQ! I would have use of 12 bits today for a specific measurement. We got a DSO-X 2004 for the purpose, I'm now trying to figure out how to get higher resolution saved data in averaging mode for that one now.

author: acbern
author_rank: Frequent Contributor
timestamp: September 18, 2015, 08:07:23 am
content: If you want to calibrate say a signal generator's output, more bits (and of course only if this translates into a better accuracy spec, which would be expectable; have not checked your specific scope's spec) are essential. As these scopes all have measurement menues to do e.g. a peak to peak measurement (potentially with avaraging to eliminate noise), resolution of the screen is not the issue here.

author: Karel
author_rank: Super Contributor
timestamp: September 18, 2015, 08:09:47 am
content: Quote from: nbritton on September 18, 2015, 05:11:01 amYou make the misstake to assume that the output of the ADC is scaled to fit in the visible vertical range on the screen. This is not the case. Only a (big) part of the output range of the ADC is actually visible on the screen.Here is one explanation:http://beyondmeasure.rigoltech.com/acton/attachment/1579/f-01b1/0/-/-/-/-/file.pdfFurther, with highspeed 14-bit ADC's usually the two or three lowest significant bits are useless because of noise and non-linearity.The effective number of bits is somewhere between 9 and 11 bits. Still a big improvement.

author: rs20
author_rank: Super Contributor
timestamp: September 18, 2015, 08:49:35 am
content: Quote from: acbern on September 18, 2015, 08:07:23 amBut doesn't noise almost always dominate for any given sample? You can overcome this with hi-res mode, but then again you can do high-res mode with an 8 bit DAC and end up with a ENOB of more than 8 bits, which isn't limited by quantisation noise?

author: daqq
author_rank: Super Contributor
timestamp: September 18, 2015, 09:22:47 am
content: QuoteYou can zoom at it, analyze it later with more resolution in any external device. Also, the automatic scope voltage measurements get more decimal places. All in all more resolution of any kind means more data for you to use.