Typo? I didn't think we had sample rates anywhere near that high!
https://www.tek.com/en/documents/application-note/real-time-...
What you can do, if and only if you have an exactly repeating signal triggering at the same point within a cycle, is change the delay between the trigger and sample, and repeat. In other words, sample at different times within the same signal (since it's exactly repeating), to build up samples in time, of that waveform, to whatever time resolution you want.
Of course, you're limited to any noise in the trigger, variation in the signal, etc.
This is how you can record light moving through your garage [1]!
The number he's referring to is in units of samples per second. It's not doing interpolation between samples, to achieve a high samples per second, because that's not possible, which is my point. Interpolation results in an imagined value, but samples are measured values.
It would be correct to say that the values between samples are interpolated, but the subject of interpolation isn't applicable for anything mentioned in this comment chain.
The only time these are interpolating is when they are visualizing, there is no point (hah) in storing interpolated data, you can generate that whenever you want.
You have to have the 240V model of the scope to run all four channels at full rate (110GHz) though.
The calibration procedure on the scope fiddles with the time alignment to get the different DACs correctly offset so that the combined signal is correct.
The hybrid ceramic input boards in their metal cases are a thing of beauty, fragile (don't ask how I know), but beautiful.