Products > Test Equipment
Rigol DG800 (long) list of problems and the sad death of a FPGA
MarkoAnte:
Update:
Still no word form Rigol.
But I was at a electronics fair and got a opportunity to test Siglent DSG 1032x. We tested the same sin and square wave at 1Mhz and it had no problems starting. The sin wave started 1 cycle before the square wave but both signals were clean. I should get the FG for some testing and will post pictures of how it starts.
bitseeker:
Interesting investigation. Following along.
ebastler:
--- Quote from: thinkfat on January 20, 2020, 04:28:00 pm ---Talking about strange behavior, my SDG2042X doesn't hold phase between channels if one of them is at a very low frequency. When setting a 10MHz sine wave on one and a 1Hz PWM on the second channel, phase shifts by 90° every second.
--- End quote ---
--- Quote from: Siglent on January 20, 2020, 09:00:46 pm ---Hello Thinkfat. You can contact our EU support team by writing support-eu@siglent.com and they will be able to assist you. - Jason, SIGLENT North America
--- End quote ---
Hi Thinkfat -- just curious: Did you reach out to Siglent, and did they have a solution? I have the same SDG, and am generally pleased with it. If Siglent were actually able to provide solutions for that kind of issue, I'd be very pleasantly surprised!
thinkfat:
--- Quote from: ebastler on February 16, 2020, 08:58:07 am ---
--- Quote from: thinkfat on January 20, 2020, 04:28:00 pm ---Talking about strange behavior, my SDG2042X doesn't hold phase between channels if one of them is at a very low frequency. When setting a 10MHz sine wave on one and a 1Hz PWM on the second channel, phase shifts by 90° every second.
--- End quote ---
--- Quote from: Siglent on January 20, 2020, 09:00:46 pm ---Hello Thinkfat. You can contact our EU support team by writing support-eu@siglent.com and they will be able to assist you. - Jason, SIGLENT North America
--- End quote ---
Hi Thinkfat -- just curious: Did you reach out to Siglent, and did they have a solution? I have the same SDG, and am generally pleased with it. If Siglent were actually able to provide solutions for that kind of issue, I'd be very pleasantly surprised!
--- End quote ---
Yes, I did contact the EU support, but they were not really able to help. They said they could not reproduce the issue and if I wasn't able to solve it I should send the device back for replacement because clearly, then the hardware would be faulty. :palm:
Of course it wasn't. I eventually found an obscure setting in the Output configuration which synced the two channels and eliminated the phase shift.
Only now, possibly after updating to the latest firmware I have a different issue: Even if I clock the device from an external source (GPSDO) I get a significant frequency offset. I tried feeding a 10MHz signal into my TIC and clocked it against a 1PPS from a GPS and what came out had a very significant drift. I know I did the same test with the factory firmware and it didn't exhibit that problem.
2N3055:
Tried on both DG1062Z and SDG6052X.
At no point they swung negative on switch on. 1MHz 50% pulse, 0-5V. DG1062Z has some relay bounce on switch on, and SDG6052X also have switch-on artefacts.
But not going negative. Ever.
I have one reminder though. When generating logic level signals, you should always enter voltages as Low/high level pair. If you enter it as voltage P-P + offset, it is easy to send wrong voltages to circuit.
Generators don't have full output swing at all frequencies.
On DG1062Z:
You setup 1 MHz pulse 50% ratio, 5V P-P and 2.5V offset and you get nice 0 to 5 V signal.
Then you change frequency to 15 MHz. What happens? Since generator can't swing 10V P-P at that frequency but only 5V P-P, it will KEEP amplitude and CHANGE offset. Your signal just got reconfigures to output -2,5 to +2,5V on output. This I believe is what happened here.
It is algorithm, in which Rigol, when they get to the point hardware cannot swing it anymore, they chose to keep P-P swing and decrease offset to reach what is output capable at that frequency.
DG1062Z can swing 0-5V (10V P-P) up to 10 MHz. If you go to 11MHZ it will switch to 5V P-P and screw up offset. And might kill something on the output.
SDG6052X can swing 0-5V up to full square wave frequency (150 MHz). One of the reasons I got it.
But if you try with higher amplitude (like 0-7V), then it will move upper amplitude (7V to 6V) and also will move low from 0V to 1 V.
So it will keep OFFSET and decrease only amplitude. Never going negative.
So on Rigol DS1062Z, generator can change voltage settings on it's own, going negative, when simply going with frequency too high.
On Siglent SDG6052X it will also change signal while changing frequency. But it won't go negative, just not have wanted levels anymore.
Both of them will show it on the screen. But also wont make any warning it's about to do it...
And both could be enhanced by software to deal with that situation better.
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