RIGOL DG1022 sweep signal amplitude problem - Page 1
Forum section: electronics / testgear

author: greasemonkey
author_rank: Contributor
timestamp: June 17, 2021, 03:49:49 pm
content: This is a 1Vpp, 3 second sweep of a sine signal (1Hz to 20MHz). The oscilloscope is in roll mode.As you can see the amplitude starts dropping after 10MHz and at 20MHz it is 720mVpp. Is this normal? Could someone reproduce it?Thing I have checked:- The transmission line is 50Ohm terminated.- When it is not sweeping the signal is 1Vpp at 20MHz- The firmware is the latest

author: duckduck
author_rank: Frequent Contributor
timestamp: June 17, 2021, 05:26:58 pm
content: Quote from: greasemonkey on June 17, 2021, 03:49:49 pmYou are not crazy.EDIT:This isn't some aliasing issue with the scope. When the timebase is set to something more common, say 100nS, it is possible toseethe sine wave shrink in the vertical dimension (voltage) as the frequency approaches 20MHz (when the DG1022 is set to sweep). In static frequency mode, changing the frequency on the DG1022 (using the rotary encoder) from 1 Mhz to 20 MHz in 1 MHz steps results in the output remaining between 1.01 Vpp - 1.03 Vpp.TEST SETUP:Rigol DG1022Firmware version: 00.02.00.06.00.02.07CH1 output set to 50 OhmSine wave, 1VppSweep:Start: 1HzStop: 20MHzTime: 3sRigol DG1022, channel 1 --> Amphenol 50 Ohm BNC-BNC cable, 36" (~1 meter) --> Amphenol 50 Ohm BNC-BNC terminator --> Rigol DS1202Z-E

author: greasemonkey
author_rank: Contributor
timestamp: June 17, 2021, 06:36:36 pm
content: Thank you duckduck. So it seems to be a ...feature.Can anyone try it on another waveform generator? A DG800 maybe? Or a Siglent?

author: duckduck
author_rank: Frequent Contributor
timestamp: June 17, 2021, 07:17:49 pm
content: Well, now it's a good excuse for you to buy a new signal generator. Maybe give the competition a try? The SDG830 looks pretty: NAhttps://siglentna.com/waveform-generators/sdg800-series-functionarbitrary-waveform-generators/EUhttps://www.siglent.eu/product/1139868/siglent-sdg830-30mhz-function-arbitrary-waveform-generatorand is not too pricey at an MSRP of USD269 / €199 w/o VAT. Make sure to post a screen-grab of the sweep for us!Fortunately, this DG1022 issue is not much of a problem for me since 99.9% of my work is from 20Hz - 20,000Hz, and the Rigol DG1022's sweep is pretty flat within that range. Iamworking on a mouse-scrambler for the garage which sweeps around 34kHz, but it just needs to be sine-wavish-ish and the output level just needs to be "loud". Even so, that's not outside of my core interest of audio, I'm just moving up(?) to small-mammal audio.Image: 20Hz-20,000Hz sweep. Sweep period 1s.

author: greasemonkey
author_rank: Contributor
timestamp: June 17, 2021, 08:26:32 pm
content: Quote from: duckduck on June 17, 2021, 07:17:49 pmDon't worry about that. When it comes to TE we can all find excuses to justify a new buy to ourselves (don't try to convince the wife though. Always keep separate bank accounts)Quote from: duckduck on June 17, 2021, 07:17:49 pmI kind of had my eyes on the DG811. It's hard to beat that 16bit 100MHz combination.That being said the DG1022 is still a solid generator and has really covered my needs all these years. I maybe used the sweep function 4-5 times. I mostly use arbitrary waveforms up to 100kHz. I even wrote a python script recently and I can now load any mathematical function to it from the USB port.It would be interesting to see how other waveform generator behave. Searching the internet did not return any interesting results about this problem.

author: duckduck
author_rank: Frequent Contributor
timestamp: June 17, 2021, 10:31:15 pm
content: Quote from: greasemonkey on June 17, 2021, 08:26:32 pmThe DG811 is especially interesting for two reasons:1) It is hackable:Quote from: tatel on June 14, 2021, 08:05:34 pm2) It is supported by Sigrok:https://sigrok.org/wiki/Supported_hardware#Function_generatorsQuote from: greasemonkey on June 17, 2021, 08:26:32 pmI agree that it is hard to beat the bang/buck of the DG1022 for my purposes (hobby audio electronics) when purchased used for ~USD120.

author: Gary350z
author_rank: Regular Contributor
timestamp: June 18, 2021, 12:43:13 am
content: I verified this problem on my Rigol DG1022. It is the same as desccribe by greasemonkey and duckduck.I tried the same test on my Siglent SDG2122X Arbitrary Waveform Generator and it works properly.

author: Gary350z
author_rank: Regular Contributor
timestamp: June 18, 2021, 12:47:37 am
content: Quote from: duckduck on June 17, 2021, 07:17:49 pmWhat is a mouse-scrambler?

author: duckduck
author_rank: Frequent Contributor
timestamp: June 18, 2021, 06:04:44 am
content: Quote from: Gary350z on June 18, 2021, 12:47:37 amA handful of cheap modules thrown into a box together to annoy mice. I am reminded that I should fuse this thing so it doesn't burn the house down. I know they sell stuff like this but I want to set the frequency and and output level.Photocell controlled dusk-to-dawn power-switch --> wall-wart SMPS --> 34kHz sine wave generator --> audio amplifier --> piezo tweeters