Rigol DS2000 hi-res mode vs mem depth - Page 1
Forum section: electronics / testgear

author: Circlotron
author_rank: Super Contributor
timestamp: October 17, 2013, 11:00:13 pm
content: Hi all.In the DS2000 scopes there is a so-called "hi-res" mode and I understand this to be that for the lower sweep speeds at least, each dot gets sampled a number of times and the average of these samples is then displayed as a single dot (in dot mode). The mem depth setting seems to affect the smoothness of the resulting display. How many times is each dot sampled and does the mem depth affect this? What are the tradeoffs?

author: JDubU
author_rank: Frequent Contributor
timestamp: October 17, 2013, 11:14:07 pm
content: Quote from: Circlotron on October 17, 2013, 11:00:13 pmAccording to this article:http://www.premier-electric.com/files/Cygnal/AppNotes/AN018.pdfTo get 12 bits of equivalent resolution ("hi-res" mode) from an 8 bit ADC would require 256 times oversampling.

author: Galaxyrise
author_rank: Frequent Contributor
timestamp: October 17, 2013, 11:25:53 pm
content: DS2000 high res mode works by changing the decimation algorithm used to go from sample memory to display memory. Memory depth affects the result since memory depth affects how many points are in the sample memory to average.Since you can only get one point per pixel column, I prefer to think of the DS2000 high res mode as a funky bandwidth limit the eliminates frequencies too high to see at the current timebase. That's not strictly accurate, but it can be used like that.

author: marmad
author_rank: Super Contributor
timestamp: December 28, 2013, 01:50:19 am
content: Quote from: Circlotron on October 17, 2013, 11:00:13 pm@Circlotron:I just ran across this old thread and thought I'd post this for you here (in case you didn't see it over at the DS2000 review thread) since it might be useful for you.We had a discussion of High-Res mode back in November in that thread, and after some tests, I came up with the following chart which illustrates the averaged samples and bandwidths of High Res mode at different memory depths from 500ns to 100ms.The number of samples averaged:10 bits = 16 samples per dot11 bits = 64 samples per dot12 bits = 256 samples per dot

author: SArepairman
author_rank: Frequent Contributor
timestamp: December 28, 2013, 02:25:47 pm
content: this is also a nice way to get extra resolution from your regular microcontroller ADC if you have the CPU cycles for it.its not really averaging either. You add them all up and slice some digits, at least to do it CPU efficient.

author: marmad
author_rank: Super Contributor
timestamp: December 28, 2013, 02:34:21 pm
content: Quote from: SArepairman on December 28, 2013, 02:25:47 pmOh yes, it IS averaging. In fact, the "proper" name for it issuccessive sample averaging.

author: SArepairman
author_rank: Frequent Contributor
timestamp: December 28, 2013, 02:45:59 pm
content: Quote from: marmad on December 28, 2013, 02:34:21 pmi guess so, but typically you would right shift the result instead of doing typical division. it might be obvious to experienced programmers but I think that its a trap for young players.

author: Krisztián
author_rank: Contributor
timestamp: September 16, 2018, 12:25:32 am
content: Hi all,Is it possible to get more than 8 bit sample data from Rigol DS2000 when using average or hi-res mode? Older Tektronix scopes (TDS 410A ... TDS784D) able to output 2 byte samples and have a very handy vertical zoom feature to take advantage of more than 8 bit samples.Thanks for answers in advance!