Siglent SDG2000 help needed

[Grandchuck]

  I have some weird anomaly with my generator that seems to appear only on ARB waveforms and only those with small duty cycles or those with very brief segments.  The generator seems normal in other respects.

My equipment is the SDG2122X, Software 2.01.01.38R4, Hardware 01-07-00-41-00

Please try this with your SDG: (step by step procedure provided in case you need it)

1/ Power on
2/ Set frequency to 4 MHz (or higher)
3/ Push Waveforms button ... Page1/2 ... Arb ... ArbType ... Built-in ... Common ... Page2of2 ... Square ... Duty01
4/ Output On
5/ Do you find that the waveform cycles on and off over 8 to 20 second intervals   

[egonotto]

Hello,

there are also problems with the SDG6000X. The amplitude changes.

Best regards
egonotto

[Martin72]

Hi egonotto,

What settings do you use on your SDG6000?

Will try to recreate it on my SDG6000...

[Mahagam]

Its a problem of Duty01 waveform. Try to set 20MHz frequency and then decrease a frequency at a tiny step. You will see a interrupted waveform.

[Martin72]

I found that out myself.
The amplitude does indeed decrease at frequencies above 4 MHz, and at higher frequencies the signals partially disappear.
This “effect” is not seen with Duty01 at higher duty cycles.
(SDG6052X)

[Grandchuck]

Here it is with the waveform set at Duty02.  The signal is now uninterrupted but the amplitude is changing.

[Grandchuck]

Here is another example of the SDG ARB weirdness.  The SineVer waveform has a steady, brief negative pulse at 1 kHz but at 100 kHz it comes and goes.  Investigation using the oscilloscope statistical/histogram feature provides interesting information.  1kHz and 100kHz results are shown (note the bimodal distribution at 100kHz). 

Modern oscilloscopes can have truly wonderful and powerful features!

[Tjuurko]

The SineVer waveform has a steady, brief negative pulse at 1 kHz but at 100 kHz it comes and goes.

At a frequency of 100 kHz, the duration of this negative pulse (0 -> -10V -> +10V) is total 10us/16384=610ps

[Grandchuck]

SineVer zooms below.

Does anybody have any idea how this comes about.  I have been looking at ARB block diagrams/theory and cannot come up with anything

Caption on second screen capture is wrong.  The duration of the negative pulse is 4.4 seconds

[Tjuurko]

All built-in Arb-signals (Waveforms -> Page 1/2 -> Arb -> Arb Type -> Built-In) consist of 16384 points.
The exception is 2 signals: demo1_375pts (375 points) and demo2_3kpts (3000 points).

For "TrueArb mode" (the signal frequency and shape is guaranteed), the maximum frequency cannot exceed 4.57763671875 kHz (75 MSa/s). 75M/16384=4.57763671875 kHz

For "DDS mode" (the signal frequency is guaranteed), the maximum frequency should not exceed 18.310546875 kHz (300 MSa/s). 300M/16384=18.310546875 kHz
If you exceed 18.310546875 kHz, then the signal shape is not guaranteed.
The "DDS mode" with a frequency of 20 MHz should have no more 15 points.
The "DDS mode" with a frequency of 4 MHz should have no more 75 points.