Thanks for making this very good introduction to programmable supplies and what appears as a review of the Rigol models. The imagry is very clear, and your lab is incredibly clean and well equipped.
Its great you provide over 1 hour of material. I wish I heard more about the Rigol against the Agilent, as aside from the ripple, I'd like to see its OVP protection and line regulation performance; program ability is moot if the basic power section isn't as clean or protected as Agilents, or as written in the spec sheet. A tear down would help too, as looking at the construction and parts will give me an idea on what it can do.
It could help more experienced folks if basics are separated from a product review.
The noise demonstrated on the scope is much higher than the Rigol or Agilent specification, a good low cost [ $< 80] linear supply can easily deliver under 1Vrms, > 5-10x less than the values demonstrated. It would be a shame to have programmability and then get such noise, if indeed this occurs.
The waveforms however, suggest there is something else causing it, not likely from the supply output; they look very much like SMPS noise from any device sharing the same ground and branch circuit, also it would be odd to have such noise in, what I hear are linear supplies.
I would bet those waveforms are there with scope probes alone, or if the user touched the probes [ as I think happened], or when attached to the PSU with power off; taking the power cord off the PSU may not appreciably affect those spurs. When the probes are attached to the Agilent, it seems more constructive interference. When checking ripple I insure PSU outputs are floating, but the measuring device too must float to reduce EMI and ground loops; an earth grounded scope will pick up Wifi, nearby SMPS - even the scopes own PSU, cellphones and radio transmissions, so the overall noise is a mix of many sources, not necessarily that of the PSU being tested.
Looking forward to more reviews. Much appreciated!