Author Topic: Rigol DSA815-TG Video Ave. Bug?  (Read 4723 times)

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Offline xrunner

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Rigol DSA815-TG Video Ave. Bug?
« on: February 01, 2016, 05:50:39 AM »
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 ...  :-//
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Offline pa3bca

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Re: Rigol DSA815-TG Video Ave. Bug?
« Reply #1 on: February 01, 2016, 06:06:01 AM »
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...
 

Offline xrunner

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Re: Rigol DSA815-TG Video Ave. Bug?
« Reply #2 on: February 01, 2016, 06:15:54 AM »
... but I remember that the detector type changes fro peak to average and stays that way.
VERY annoying bug...

Thank 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.  :-+
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Offline pa3bca

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Re: Rigol DSA815-TG Video Ave. Bug?
« Reply #3 on: February 01, 2016, 08:04:51 AM »
Thank 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.  :-+
As 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?)
 

Offline xrunner

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Re: Rigol DSA815-TG Video Ave. Bug?
« Reply #4 on: February 02, 2016, 12:26:40 AM »
As far as I know this bug is present in all firmware versions I know off. I never reported it (sry).

I just submitted the report. Will let you know what they say.
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Offline xrunner

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Re: Rigol DSA815-TG Video Ave. Bug?
« Reply #5 on: February 03, 2016, 10:14:08 AM »
Received via email today -

Quote
I'll have a chance to try this out tomorrow.

Can you tell me the firmware level the DSA is at? The latest is v1.15.

If you have screen shots please go ahead and send them to me.

Best regards,

Steve Huss

Applications Engineer
Rigol Technologies
10200 SW Allen Blvd. Suite C
Beaverton, OR 97005
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Online georges80

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Re: Rigol DSA815-TG Video Ave. Bug?
« Reply #6 on: February 04, 2016, 10:05:01 AM »
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.
My 'job': www.taskled.com
 

Offline xrunner

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Re: Rigol DSA815-TG Video Ave. Bug?
« Reply #7 on: February 06, 2016, 12:17:17 AM »
Response -

Quote
Hi Mike,

Changing the trace type to Video averaging also changes the detector type to Voltage Avg. Changing the trace type back to Clear Write does not change the detector type back to Pos Peak.

You can do this manually to get back to the original readings.

Steve

Here's my reply -

Quote
Hello Steve,

OK, if that's the problem then I can get back to the original setting ... but ... why should the operator have to do that at all?

Shouldn't the firmware be changed to make the machine do that when going back to Clear/Write? I would still consider it a bug that needs to be addressed, wouldn't you?

Thanks,
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Offline pa3bca

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Re: Rigol DSA815-TG Video Ave. Bug?
« Reply #8 on: February 06, 2016, 07:50:29 PM »
Quote
Hi Mike,

Changing the trace type to Video averaging also changes the detector type to Voltage Avg. Changing the trace type back to Clear Write does not change the detector type back to Pos Peak.

You can do this manually to get back to the original readings.

Steve

WTF :palm:
Although 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!
 

Offline pa3bca

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Re: Rigol DSA815-TG Video Ave. Bug?
« Reply #9 on: June 16, 2016, 05:21:17 PM »

I DON'T think that there is a bug here, but rather that the Clear Write is working as intended.  Selecting Clear Write is NOT supposed to re-set/change the Detector Type or Video Averaging.  If you check with the HP, R&S, and etc. Spectrum Analyzer's operation you will find that Clear Write (or equivalent) function works the same with them (does not change the Detector Type).

I believe that Rigol's (Tech. Rep.) Steve meant to say (is saying) that that the Clear Write is function properly, although you can change the Detector Type if required manually.
I'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.
 

Offline pa3bca

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Re: Rigol DSA815-TG Video Ave. Bug?
« Reply #10 on: June 16, 2016, 10:26:52 PM »

I DON'T think that there is a bug here, but rather that the Clear Write is working as intended.  Selecting Clear Write is NOT supposed to re-set/change the Detector Type or Video Averaging.  If you check with the HP, R&S, and etc. Spectrum Analyzer's operation you will find that Clear Write (or equivalent) function works the same with them (does not change the Detector Type).

I believe that Rigol's (Tech. Rep.) Steve meant to say (is saying) that that the Clear Write is function properly, although you can change the Detector Type if required manually.
I'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.

Yes, I feel that there is not a issue or Bug here!
When you initially select a Average mode (it doesn't matter if you had previously selected Clear Write or not), the result will be Averaging (as applicable) with the default being 100 samples (this value can be manually changed).  Pressing Clear Write will then simply refresh your data (in this example the Average data, without changing the Detector type).  If you then decide that you no longer want the Averaging that was initially selected, you will have to manually select Your your desired Detector type, etc (i.e. Peak, etc.).
But 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.
 

Offline xrunner

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Re: Rigol DSA815-TG Video Ave. Bug?
« Reply #11 on: June 16, 2016, 10:39:28 PM »
I DON'T think that there is a bug here, but rather that the Clear Write is working as intended.  Selecting Clear Write is NOT supposed to re-set/change the Detector Type or Video Averaging.  If you check with the HP, R&S, and etc. Spectrum Analyzer's operation you will find that Clear Write (or equivalent) function works the same with them (does not change the Detector Type).

I believe that Rigol's (Tech. Rep.) Steve meant to say (is saying) that that the Clear Write is function properly, although you can change the Detector Type if required manually.

I just reviewed the manual for the DSA815. It clearly states that Clear / Write is a trace 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 and type is Trace 1 and Clear Write.

(pg. 2-34, et al)
« Last Edit: June 16, 2016, 10:49:30 PM by xrunner »
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