Rohde & Schwarz RTB2004 Timebase Quirk

[EEVblog]

Why does the Rohde & Schwarz RTB2004 have an 80ns timebase setting instead of 100ns?

[HackedFridgeMagnet]

Yeah mine does the same?? firmware version 2.00

obviously you can manually set 100ns but you shouldn't need to.

[EEVblog]

Yeah mine does the same?? firmware version 2.00
obviously you can manually set 100ns but you shouldn't need to.

I have the latest firmware, updated yesterday.
Yes, you can use the fine adjust, but that's beside the point.

[Rich@RohdeScopesUSA]

I'm checking on this - will update ASAP.

-Rich

[nctnico]

I just checked. The RTM3004 does the same. 10ns 20ns 40ns 80ns 200ns. This has to be some kind of feature 

[EEVblog]

I'm checking on this - will update ASAP.
-Rich

Thanks.
I'm sure there is some very deliberate technical reason for it, will be interesting to find out.

[Hydrawerk]

This might be an easter egg.

[Rich@RohdeScopesUSA]

I'm checking on this - will update ASAP.
-Rich

Thanks.
I'm sure there is some very deliberate technical reason for it, will be interesting to find out.

Hi Dave - here's the response from R&D.  As you suspected, there is a deliberate reason for it:

For this matter, the ratio between sampling rate and pixel per div are important. For 50 ns and 100 ns timebase, the result would non-integer numbers for the pixel per div, e.g. 0.63 for 50 ns at 1,25GSa/s. In principle this could be displayed, but it just would not look very good. For 40 ns and 80 ns the pixel per div are integers, so displaying the measurements looks better.

-Rich

[Hydron]

Ah this makes sense - checking a screenshot each div looks to be 100 pixels each, which would be exactly 1 pixel per sample (not per div - slightly lost in translation here?) at 2.5GSa/s and 1.25GSa/s for 40 and 80ns/div respectively. At other time bases the sampling isn't going to line up like that so I guess that's why they go back to traditional 1-2-5 ratios.

[Rich@RohdeScopesUSA]

Ah this makes sense - checking a screenshot each div looks to be 100 pixels each, which would be exactly 1 pixel per sample (not per div - slightly lost in translation here?) at 2.5GSa/s and 1.25GSa/s for 40 and 80ns/div respectively. At other time bases the sampling isn't going to line up like that so I guess that's why they go back to traditional 1-2-5 ratios.

Ha!  Yes - pixel per sample.  Not division.   

-Rich

[EEVblog]

Thanks, makes sense, all pixels matter!

[KlausF]

Hi Dave

Thought you gave the R&S RTC2004 scope away.

Rohde & Schwarz RTB2004 Giveaway Winner!

[Fred27]

For most giveaways it seems to be a "one for you to keep and one to give away" deal from the manufacturer.

[Keysight DanielBogdanoff]

It would be crazy for us to not send Dave an extra one to keep!

Thanks for the info, Rich, I never thought about the pixel count as a design consideration.

[mikeselectricstuff]

Oddly the reference waveform timebase setting goes 10-20-50nS

Of course you can get the 50/100nS settings using fine adjust

See atattched for difference between 40 and 50nS