Hi again tautech! Back again. Just checked the firmware and noticed it matches the latest version. I might have a chat to a siglent representative to discuss this observation about the SDG-1025 AM carrier amplitude (with zero modulation) being half of the front panel LCD setting. Thanks once again.
This is how it works. If you compare to real RF generator. Typically they keep carrier level.
SDG5000 (and if I remember right also SDG1000).
When you turn AM mod on carrier drop 6dBm. Independent of modulation sidebands levels.
If you select (no mod) sinewave level 1Vpp. Then turn AM on and depth 0% amplitude is 6dB less 500mVpp
Now if you change mod depth from 0 to 120% carrier level stay still constant and sidebands are how they are.
Just "know your equipment".
So, if you want 0 dBm carrier and AM mod. Just set +6dBm level.
Now if you have 0% mod you get only carrier and level 0dBm
If you now set 100% mod. You have 0dBm carrier and two -6dBm side bands.
If you set 50% mod you have now 0dBm carrier and two -12dBm side bands
It may feel strange but it may have some explanation.
If we take oscilloscope and look.
Lets think we have set sine wave and AM mod off and level
1Vpp.
We can see level is 1Vpp. Now keep level setting.
Turn AM on but keep 0%. We can see 500mVpp.
What we see if turn mod 100%. We see now that modulated signal and level is
1Vpp. It is made so that with 100% mod it do not exceed set level.
If user want set SDG maximal level what it can output. Then user turn AM on and 0% level is half. If he turn AM mod 100% output is now this max peak-peak.
If it works different and it keep carrier level as user have set with AM off, what user think if it can not modulate.
Of course it is possible to do different but who then define how it need show exactly in all circumstances and how to message and prevent possible situations when mod depth need reject or prevent some level settings depending if user turn AM mod on..etc.. Specially when user use dBm level setting and if AM is on is it better show carrier level dBm - perhaps. (now it show what is peak level IF mod depth is 100% (as it also show Vpp level IF modulation is 100%) Wrong or right for Function generator - but this is how it works.