I'll give you a hint too:
you were trying to sample a 50 MHz waveform at a 50 kHz sample rate with the keysight and at a 1 MHz Sample rate with the siglent.
if that doesn't tell you something...
the other interesting thing, which you can learn from, is that the siglent still was able to resolve a squarish wave, which is of course bogus because the frequency counter in the upper right of the screen is still displaying 50 MHz, the measurement instead would have told you the signal frequency was jumping. why? because the hardware counter/dvm are independent from the sampling system.
I can choose sample rate only by minimize time captured . I cannot choose manually . But how can I do when I have to capture 1s or 500 micros ?
Your video in Reply #834 on: Yesterday at 04:10:33 PM is totally junk. If you do not know anythjing about signals and how oscilloscopes work please tell it to readers and watchers that this all is just for fun and story wjhat happend without any knowledge about things.
Your siglent trigger counter show 50MHz.
With Siglent you are sampling this signal with 1Msa/s. Then scope show some kind of squarish waveform on the dislay. After then in stop mode you zoom in this captured alias. What you think. Yuu want teach us what is aliasing (if your signal is 50MHz as counter tell, or is it wrong) If you try to tell how oscilloscope display can fool peoples who do not understand anything what they are doing, why you do not tell it.
With Keysight situation is even more bad due to even more low samplerate.
Then reply 842, this FFT
(facts. Keysight FFT length is max 64k and Siglent max 1M)
What are you thinking or what you want show. Only what you now show is that you do not know how to use FFT (least in Siglent)
Do you think this kind of playing is something useful.
Perhaps this is some kind of humor but I do not regognize its genre. Is it some sort of satire or self-irony?
If you try some kind comparison of devices - well it do nowt work like this at all.
Do not take seriously but is it better that before you publish this kind of things you give "bullshit" warning somehow to readers. Here is also noobs watching these and all do not have enough knowledge for self filtering bullshits.
Try these with Keysight.
Signal 50MHz. 1st level 0dBm and after then 50MHz carrier AM mod 50% with 1.2kHz and carrier level -10dBm.
These last two you can not do at all with Keysight. There is no enough resolution for measure 50MHz 1.2kHz AM modulation so that you can also separate side bands and measure them. In this place can say: Scrap the Toys, Get a Real Oscilloscope.