I guess I have to eat crow. There is a slight -- and I stress the word SLIGHT -- but consistent difference when the Rigol is told it is a DS1152E-EDU vs DS1102E. I have flashed and reflashed back and forth several times, (downgrade to 2.02SP2, change model and serial number, verify new info acccepted, upgrade to 2.04SP1, run self-calibration) and set up the identical configuration -- view dots, persistence on, average on, sinx/x off, normal trigger, 2ns/dif, 2v/div, measure to display max volts and rise time, manual cursors carefully adjusted to 10% and 90%.
As a DS1152E-EDU, the rise time is consistently about 1.84ns, +/-0.04ns. As a DS1102E, the rise time is consistently 1.96ns, +/-0.04ns. The margin of error is based on my manual skills considering the resolution of the display (bear in mind that I am now so, ummm,
mature, that my reading glasses now need reading glasses
![Sad :(](https://www.eevblog.com/forum/Smileys/default/xsad.gif.pagespeed.ic.L3FGyzQrjB.png)
) and even the automatic measurement flickers by 0.02ns from time to time. Anyway, here are some representative screen shots of each:
As a DS1102E:
![](http://picturehosting.verhey.org/rigol/1102hard3.bmp)
and as a DS1152E-EDU:
![](http://picturehosting.verhey.org/rigol/1152hard1.bmp)
I can not explain the difference. It makes no sense to have so slight a difference anyway! But it does seem to be real, as I said, I went back and forth several times to rule out environmental variables like ambient temperature, battery voltage, circuit burn-in, etc.
The only thing I can think of is that the area of memory where the data is stored may be changing as a result of the flash process. I recall reading something about the Rigol having 8 megs of flash ram but the F/W files are all 4 megs or less. The person was theorizing that the F/W is flashed to alternate halves each time (so it does not overwrite the existing F/W) and that the remaining 4 megs may then be used as data storage space. If this is so, then perhaps the different memory areas have slightly different access times which affects the sample rate ever so slightly??? I have no idea if this could be so, perhaps someone with more knowledge about the internals (drieg?) might have a better guess.