Rohde & Schwarz RTB2004 Timebase Quirk - Page 1
Forum section: electronics / testgear

author: EEVblog
author_rank: Unknown
timestamp: November 13, 2018, 01:28:18 am
content: Why does the Rohde & Schwarz RTB2004 have an 80ns timebase setting instead of 100ns?

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: November 13, 2018, 01:42:40 am
content: Yeah mine does the same?? firmware version 2.00obviously you can manually set 100ns but you shouldn't need to.

author: EEVblog
author_rank: Unknown
timestamp: November 13, 2018, 01:46:31 am
content: Quote from: HackedFridgeMagnet on November 13, 2018, 01:42:40 amI have the latest firmware, updated yesterday.Yes, you can use the fine adjust, but that's beside the point.

author: Rich@RohdeScopesUSA
author_rank: Frequent Contributor
timestamp: November 13, 2018, 05:07:50 pm
content: I'm checking on this - will update ASAP.-Rich

author: nctnico
author_rank: Super Contributor
timestamp: November 13, 2018, 05:12:38 pm
content: I just checked. The RTM3004 does the same. 10ns 20ns 40ns 80ns 200ns. This has to be some kind of feature

author: EEVblog
author_rank: Unknown
timestamp: November 13, 2018, 09:40:52 pm
content: Quote from: Rich@RohdeScopesUSA on November 13, 2018, 05:07:50 pmThanks.I'm sure there is some very deliberate technical reason for it, will be interesting to find out.

author: Hydrawerk
author_rank: Super Contributor
timestamp: November 13, 2018, 11:35:11 pm
content: This might be an easter egg.

author: Rich@RohdeScopesUSA
author_rank: Frequent Contributor
timestamp: November 15, 2018, 02:56:58 pm
content: Quote from: EEVblog on November 13, 2018, 09:40:52 pmHi 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

author: Hydron
author_rank: Super Contributor
timestamp: November 15, 2018, 03:29:28 pm
content: 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.

author: Rich@RohdeScopesUSA
author_rank: Frequent Contributor
timestamp: November 15, 2018, 04:05:41 pm
content: Quote from: Hydron on November 15, 2018, 03:29:28 pmHa! Yes - pixel per sample. Not division.-Rich

author: EEVblog
author_rank: Unknown
timestamp: November 15, 2018, 11:30:47 pm
content: Thanks, makes sense, all pixels matter!

author: KlausF
author_rank: Contributor
timestamp: November 27, 2018, 05:57:26 pm
content: Hi DaveThought you gave the R&S RTC2004 scope away.Rohde & Schwarz RTB2004 Giveaway Winner!

author: Fred27
author_rank: Unknown
timestamp: November 27, 2018, 07:26:55 pm
content: For most giveaways it seems to be a "one for you to keep and one to give away" deal from the manufacturer.

author: Keysight DanielBogdanoff
author_rank: Unknown
timestamp: November 28, 2018, 05:25:56 pm
content: It would be crazy for us tonotsend Dave an extra one to keep!Thanks for the info, Rich, I never thought about the pixel count as a design consideration.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: November 30, 2018, 09:13:45 am
content: Oddly the reference waveform timebase setting goes 10-20-50nSOf course you can get the 50/100nS settings using fine adjustSee atattched for difference between 40 and 50nS