Rigol DG822 Function Generator Channel Settings For Making A Triggered Sweep? - Page 1
Forum section: electronics / testgear

author: t1d
author_rank: Super Contributor
timestamp: July 21, 2022, 08:19:58 pm
content: BackgroundI have hobbyist level skills, with nice lab equipment that is smarter than I am.I am trying to make my first triggered sweep. I am using my DG822 Function Generator and my Siglent 1104X-E Scope.I have learned that I need three things from the DG822.1) A Source Sweep Signal2) A Synchronization/Trigger Signal3) Channel Settings that tie and coordinate #1 and #2.I used Channel #1 for my Source Sweep Signal. I am working with a sweep from 20Hz to 20KHz, to test a passive, RC Bandpass Filter. I believe that I have these setting sussed out, as I can find (independently) this signal on the scope.I used Channel #2 for my Synchronization/Trigger Signal. I used a single Burst Pulse Square Wave, being one second in duration. (Do not be tempted to use a Pulsed Continuous Wave. The FG will complain that a Burst is required.) I believe that I have these setting sussed out, as I can find (independently) this signal on the scope.The Source Sweep Signal outputs the lowest value of the sweep range, continuously. I believe the 822 is operating correctly, in making this behavior (but, I am not sure of what benefit it is.) It does create a problem, though. It trips the scope trigger, at the wrong time. I can see the sweep go by, but I can't capture it. So, the Synchronization Signal is used, instead, to trigger the scope. I get this far along the learning curve, but I have yet to capture an appropriate single sweep.The Channel Settings are what ties the two together. They are also what is the most in question. The Channel Settings chapter begins at page 111 of the manual. The Channel Settings menu is accessed by tapping the Channel Tabs, in the lower, left corner of the FG screen, twice. The manual makes some unclear statement about the output being sent out through the connectors on the back of the FG. But, I continued to work using the front connectors. The most misunderstood, and likely important, of these settings is SyncSet State. I could not discern if the two channels should both be set to off, on, or some combination.I have provided my notes for the 822 Settings, as I had them set. Warning; they were scribbled down, during testing.I find the DG822 user manual to be so abbreviated as to be of little use. So, I could use some help with detailed instructions of how to set all of the settings, with emphasis on the Channel Settings. If you have a link, that would be great, too.Please and thank you, for your gracious help.

author: Zenith
author_rank: Frequent Contributor
timestamp: July 21, 2022, 09:22:52 pm
content: Having struggled through this with a Feeltech FY6800 and eventually managed to get it to work, I feel your pain. I'll try to help. I don't have a Rigol DG822, but I've had a look at the manual. It doesn't go into synchronising the sweep as far as I can see. It looks like a more sophisticated instrument than the FY6800. I can't help with detailed settings.Get it to sweep as displayed on a scope. Then you need at least one of two things; the sweep ramp or a sync pulse at the start of the sweep.When it's sweeping, check the various outputs with a scope to see if there's anything that looks like the sweep ramp. You may have to fiddle with the menus to make it available. If you find it you can either trigger the scope on the falling edge, or try using using the scope in XY mode.If you find a sync pulse, you can trigger the scope on that.When you manage to synchronise the sweep, there may be some fiddling to get a sensible scale to display on the scope.I found the sweep function on the FY6800 was useless because of the lack of a sync pulse or sweep ramp - at least I couldn't find either. FM modulation works well for sweeping.

author: TurboTom
author_rank: Super Contributor
timestamp: July 21, 2022, 09:59:38 pm
content: The DG800/900 series of AWGs has got a pretty comprehensive help function included, albeit with a tiny font...If you scroll down in the sweep menu, you will find such settings as "Source" which configures the trigger source for the sweep. Set it to "Internal" and it's sweeping all by itself wihout the need to bother another channel or an external trigger signal...Then, you can enable a marker and set the marker frequency: At that settings, the aux out of the corresponding channel (on the back side of the instrument) should change polarity, i.e. you can use it to trigger your scope.And then, there's the additional settings of Start hold and Stop hold, where you can enter a time that the initial or the final frequency should be kept constant - just what you observed. Set both to zero and the sweep repeats without interrupt.All these functions are pretty common for a modern AWG, so you may just have missed the menu items accessible by scrolling down.I hope this information may help a little setting up your generator...Cheers,Tom

author: t1d
author_rank: Super Contributor
timestamp: July 21, 2022, 10:12:33 pm
content: Thank you, Zenith, for your kind support and effort to reply.You are correct, on the elements needed. I have the sweep signal on Ch1, the pulse signal on Ch2 and I even get the 822 to output the sweep, when I press the trigger button on the 822.What I do not have is #1 and #2 synchronized, that being the third element. So, my scope is not being triggered correctly, to capture a clean, single sweep. (For clarity's sake, there are two triggers at play... The triggered output from the 822 and the receiving trigger, on the scope.)The 822 does have a synchronization function. I just don't have it operating correctly. The sync function settings are under the Channel Settings, beginning at page 111, in the manual. But, as said, those instructions are so abbreviated that I can not understand what I need to do.As for your FY6800, I think I am seeing small/easy add-on DIY circuits on YouTube being added to function generators that lack some functions. It might be worth investigating.Your reply is encouraging; thank you.

author: t1d
author_rank: Super Contributor
timestamp: July 21, 2022, 10:25:26 pm
content: Thank you, Tom. I will take your settings and give it another go. I appreciate your help.

author: Zenith
author_rank: Frequent Contributor
timestamp: July 22, 2022, 10:08:28 am
content: To add to the fun with the FY6800, there are two sync functions.One is sync in and sync out, through BNC sockets. Sync out produces a square wave version of the main output, so other FY6800s can be synchronised - not the most useful feature.Another is sync that locks both channel settings together, so alter one and the other changes identically.Both minor rabbit holes to be gone down. I'm saying this because when they talk about sync in the manual it may be totally different to what you want it to be.I hope someone comes along who has a DG822 and done this, and can explain how to do it. But I wouldn't be surprised if, incredibly, it just can't be done.I shall look out for the add-ons to the FY6800. Thank you for drawing my attention to them.

author: TurboTom
author_rank: Super Contributor
timestamp: July 24, 2022, 11:56:26 am
content: @t1d:Did you succeed with your sweep experiment?I experimented with this as well a little and got it to work basically as explained before (and as it's shown in the manual starting on page 2-56), but to enable the trigger out on the rear of the DG800/900, there's an additional setting that's a little hidden (manual pg. 2-81/2-83): The channel setting menu is enabled by tapping the corresponding channel label at the buttom left of the screen. Here you can change all kind of coupling, limiting and synchronizing related parameters.The one that's relevant for you is to make sure that SyncSet -> SyncState is "On" for the channel that you're using to output the sweep.I attached an instrument config file (delete the ".txt" before trying to upload it to your AWG) that configures CH1 to generate a linear sweep of 10Hz to 20kHz with a sweep time of 1.2s (so it fits a 12 div wide screen at 100ms/div), trigger is at 10kHz so it takes place pretty much at the center of the screen. You may want to save your own AWG's setup if its configured in a certain way that you don't want to lose before uploading the attached one.Anyway, if you know where to search for the information, Rigol's manual is pretty comprehensive and also for the beginner, quite coherent.Have fun with your new instrument,TomP.S. I don't know which firmware you are running on your AWG, but since the latest one messed up something with the internal arbitrary waveforms, you may consider to run v00.02.05.00.00 which at least doesn't have such obvious bugs... (though it's got other shortcomings, especially regarding amplitude modulation level setup)

author: t1d
author_rank: Super Contributor
timestamp: July 24, 2022, 01:14:29 pm
content: Thank you, Tom, for your efforts to go the extra mile to help me. It is very gracious of you and I very much appreciate it.No, I have not had an opportunity to try your suggestions; I have to work around health challenges. However, I look forward to using your text file setup. I will post the results, when I have them in hand.