Author Topic: Rohde & Schwarz RTB2004 Timebase Quirk  (Read 2475 times)

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Offline EEVblog

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Rohde & Schwarz RTB2004 Timebase Quirk
« on: November 13, 2018, 01:28:18 am »
Why does the Rohde & Schwarz RTB2004 have an 80ns timebase setting instead of 100ns?

 

Offline HackedFridgeMagnet

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Re: Rohde & Schwarz RTB2004 Timebase Quirk
« Reply #1 on: November 13, 2018, 01:42:40 am »
Yeah mine does the same?? firmware version 2.00

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

Offline EEVblog

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Re: Rohde & Schwarz RTB2004 Timebase Quirk
« Reply #2 on: November 13, 2018, 01:46:31 am »
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.
 

Offline Rich@RohdeScopesUSA

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Re: Rohde & Schwarz RTB2004 Timebase Quirk
« Reply #3 on: November 13, 2018, 05:07:50 pm »
I'm checking on this - will update ASAP.

-Rich
 

Offline nctnico

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Re: Rohde & Schwarz RTB2004 Timebase Quirk
« Reply #4 on: November 13, 2018, 05:12:38 pm »
I just checked. The RTM3004 does the same. 10ns 20ns 40ns 80ns 200ns. This has to be some kind of feature  :-/O
« Last Edit: November 13, 2018, 05:14:42 pm by nctnico »
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline EEVblog

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Re: Rohde & Schwarz RTB2004 Timebase Quirk
« Reply #5 on: November 13, 2018, 09:40:52 pm »
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.
 

Offline Hydrawerk

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Re: Rohde & Schwarz RTB2004 Timebase Quirk
« Reply #6 on: November 13, 2018, 11:35:11 pm »
This might be an easter egg. :)
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Offline Rich@RohdeScopesUSA

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Re: Rohde & Schwarz RTB2004 Timebase Quirk
« Reply #7 on: November 15, 2018, 02:56:58 pm »
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
 
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Offline Hydron

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Re: Rohde & Schwarz RTB2004 Timebase Quirk
« Reply #8 on: November 15, 2018, 03:29:28 pm »
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.
 
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Offline Rich@RohdeScopesUSA

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Re: Rohde & Schwarz RTB2004 Timebase Quirk
« Reply #9 on: November 15, 2018, 04:05:41 pm »
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
 
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Offline EEVblog

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Re: Rohde & Schwarz RTB2004 Timebase Quirk
« Reply #10 on: November 15, 2018, 11:30:47 pm »
Thanks, makes sense, all pixels matter!
 
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Offline KlausF

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Re: Rohde & Schwarz RTB2004 Timebase Quirk
« Reply #11 on: November 27, 2018, 05:57:26 pm »
Hi Dave

Thought you gave the R&S RTC2004 scope away.

Rohde & Schwarz RTB2004 Giveaway Winner!

 
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Offline Fred27

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Re: Rohde & Schwarz RTB2004 Timebase Quirk
« Reply #12 on: November 27, 2018, 07:26:55 pm »
For most giveaways it seems to be a "one for you to keep and one to give away" deal from the manufacturer.
 

Offline Keysight DanielBogdanoff

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Re: Rohde & Schwarz RTB2004 Timebase Quirk
« Reply #13 on: November 28, 2018, 05:25:56 pm »
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.
 

Offline mikeselectricstuff

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Re: Rohde & Schwarz RTB2004 Timebase Quirk
« Reply #14 on: November 30, 2018, 09:13:45 am »
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


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