Rigol DSA815-TG Video Ave. Bug? - Page 1
Forum section: electronics / testgear

author: xrunner
author_rank: Super Contributor
timestamp: January 31, 2016, 06:50:39 pm
content: Start the unit and use the preset scan and settings. Input a -10 dBm signal @ 100 MHz for tracking. Note in the first pic that I have a marker on the signal and have a display line set to the noise level at the beginning of the trace.Go to Trace/PF button and select Trace Type > Video Avg. Note that the noise level goes down from ~-65 dBm to ~ -75 dBm at the start, and the noise level is averaged (as it should be). Also note now the signal level is incorrect, it now shows -21 dBm.Now simply change back to the original trace setting - Clear/Write. Now note the trace did NOT go back to the original type of trace, and that the noise level did not return to the same level, and that the noise still seems to have some sort of averaging going on.Remember, all I did was turn on the unit, put in a signal at 100 MHz @ -10 dBm, and change the trace type from Clear/Write to Video Avg and back again. Something else is being changed when you select Video averaging for the noise level to actually drop, and that something is not being changed back to what it was when you re-select Clear/Write. Also, in any case, the signal power level is now wrong.Thoughts ...

author: pa3bca
author_rank: Regular Contributor
timestamp: January 31, 2016, 07:06:01 pm
content: I noticed this bug before. I am away from home so I can't check, but I remember that the detector type changes fro peak to average and stays that way.VERY annoying bug...

author: xrunner
author_rank: Super Contributor
timestamp: January 31, 2016, 07:15:54 pm
content: Quote from: pa3bca on January 31, 2016, 07:06:01 pmThank You - I checked what you said and that's it - well at least I know what the hell changed in the thing. Have you reported this? If not I may report it.

author: pa3bca
author_rank: Regular Contributor
timestamp: January 31, 2016, 09:04:51 pm
content: Quote from: xrunner on January 31, 2016, 07:15:54 pmAs far as I know this bug is present in all firmware versions I know off. I never reported it (sry).As soon as you select video averaging the detector type changes from peak to voltage average (I think ,have to check when at home), resulting in the noise floor (and often also the 'real' signals) dropping down.This bug had me stumped for a while, I seem to remember that sometimes the detector type does NOT (wrongly) change.Funny though that nobody else has reported this strange and obvious bug (but maybe the are like me: work around the bug as soon as it is identified for what is is?)

author: xrunner
author_rank: Super Contributor
timestamp: February 01, 2016, 01:26:40 pm
content: Quote from: pa3bca on January 31, 2016, 09:04:51 pmI just submitted the report. Will let you know what they say.

author: xrunner
author_rank: Super Contributor
timestamp: February 02, 2016, 11:14:08 pm
content: Received via email today -Quote

author: georges80
author_rank: Frequent Contributor
timestamp: February 03, 2016, 11:05:01 pm
content: Thanks, with good/clean feedback to Rigol they will hopefully continue to fix bugs in their products. They win and of course as customers we win.Mod: thanks for removing the previous post by someone having a bad day (obviously now gone).cheers,george.

author: xrunner
author_rank: Super Contributor
timestamp: February 05, 2016, 01:17:17 pm
content: Response -QuoteHere's my reply -Quote

author: pa3bca
author_rank: Regular Contributor
timestamp: February 06, 2016, 08:50:29 am
content: QuoteWTFAlthough I am pretty content with my Rigols (unbeatable price/performance for a hobbyist like me) their support really sucks. One might expect such a reply from a China support person but from US support?So you report a serious bug: detector type changes erroneously from peak to average to when video average is selected - this is the core bug - detector type should NOT change!!) and it does not reset when Clear write is re-selected (bug #2).And their answer is not the recognition of the bug (and the promise to report and solve it) but: "well, you can manually correct for this bug so what is your point anyway?"Duh!

author: pa3bca
author_rank: Regular Contributor
timestamp: June 16, 2016, 07:21:17 am
content: Quote from: ted572 on June 16, 2016, 12:37:46 amI'm a bit confused now. Do you mean to say that it is correct that the detector type is automatically changed from peak to voltage averaging when clear-write is changed to video averaging, but when reverting back to clear write the detector type should be left untouched?I agree with the latter, but not with the former. The bug is that the detector type is changed from peak to average when clear write is changed to video averaging.

author: pa3bca
author_rank: Regular Contributor
timestamp: June 16, 2016, 12:26:52 pm
content: Quote from: ted572 on June 16, 2016, 11:03:47 amBut sureley it is a (the) bug that the Rigol changes the detector type (from peak to voltage average) when I change Clear Write to video average? In m opinion the video averaging is done _after_ the detector, so video averaging should average the display based on the previously set detector type, eg peak detector.So why change the detector type (to voltage average) but not back? at least one of these is incorrect.

author: xrunner
author_rank: Super Contributor
timestamp: June 16, 2016, 12:39:28 pm
content: Quote from: ted572 on June 16, 2016, 12:37:46 amI just reviewed the manual for the DSA815. It clearly states that Clear / Write is atrace type- not simply a momentary sort of function. It's the basic type of trace of the unit, with no additional higher functions applied to it.Trace types:Clear Write, Freeze, Max Hold, Min Hold, Video Avg and Power Avg. Trace status: yellow denotes On and gray denotes Off.(pg. 1-19)The default trace andtypeis Trace 1 andClear Write.(pg. 2-34, et al)