More scope memory questions!

[Dan Moos]

Ok, I'm still trying to wrap my head around how waveforms are stored in my scope (un-modded Rigol 1052e)

I watched w2aew's excellent video on the matter, and that is where I get my process. The answers I get are usually not what I expect though.

Ok, the manual says in long memory mode, I should have either 512 Kpts, or 1 Mpt. I assume that means I get the lower number with both channels active, and the higher with one active.

With only one channel active, I have the scope set for 200us per division.

the scope says I'm getting 100 Meg samples.

Scope has 12 horizontal divisions.

100,000,000 * .0002 * 12 = 240,000 points.

Ok, since that's not the 1 Meg points I expected, I can think of three possibilities:

1) The record length extends beyond the screen

2) The scope doesn't always use its full memory, and changes it depending on horizontal settings.

3) My math is done improperly.

Any thoughts?

[StillTrying]

Ok, I'm still trying

No, that's me!

1) The record length extends beyond the screen

That one I think, other than at the lowest time base speeds = roll mode.

[JPortici]

easy to find out: single acquisition. now move the horizontal axis. if you see data from "outside" the screen, there you go.

[tautech]

Dan, see the animated gif in this post by rf-loop.
https://www.eevblog.com/forum/testgear/siglent-sds1000x-series-oscilloscopes/msg933997/#msg933997

Observe the sample rate, memory depth and timebase settings.