Measure Crystal Oscillator using Rigol DSO8104 or Else - Page 1
Forum section: electronics / testgear

author: hpw
author_rank: Frequent Contributor
timestamp: October 13, 2020, 10:44:41 am
content: Hi,I am currently looking for an 8..9k$ DSO (new or used) the measure/watch clock jitter:. On pure crystal oscillator as 5..50 Mhz. On clock dividers as 40...1MHz. Using Histogramm. Using Eye view. May providing jitter numbersSo the question of DSO's comes:. Sample jitter as DSO8104 uses the 10MHz out as base clock and may PLL to 10GHz ...??. So sample jitter is not given for the DSO8104, so results would be unknown until have the gear on bench. 8 Bit ADC resolution will be also a limit factor, while span / 256 and will be for 0..5V not so courseThe beef question is:Does this really expensive Rigol DS8000 series provide accurate measurements or I have to look for Keysight or LeCroy gearHp

author: 2N3055
author_rank: Super Contributor
timestamp: October 13, 2020, 11:33:06 am
content: Quote from: hpw on October 13, 2020, 10:44:41 amWhat exact jitter and stability measurements you want to do? Take a look at DSO8000 manual, it (at this time, they may add more later) support just few basic measurements. It might be enough for you, or not. Depends on you.As far as specifications go, it will do good job for measurements is does. It won't give you false numbers, so to say.It will be accurate to the specs..8 bits doesn't matter, because interpolation is used...All in all it's jitter measurements seem to be well implemented, but basic. It's forte is that it is affordable for a 2 GHZ sscope..If you need something more sophisticated, you might need to go for something more capable or specialized..It supports (from a leaflet) :The Rigol MSO8064 supports the eye measurement for all the analog channels, and also provides measurement for several parameters of the eye diagram:eye heighteye widtheye amplitudecrossing percentageQ FactorIt also supports various clock recovery methods, such as constant clock (auto, semi-auto, manual), first-order PLL, second-order PLL, and explicit clock, to meet the demands of customers for different application scenarios.Jitter analysisThe jitter analysis is mainly used to measure and analyze the clock jitter. The Rigol MSO8064 can accomplish the following jitter analysis items:TIEcycle to cycle+width to +width-width to -width

author: TurboTom
author_rank: Super Contributor
timestamp: October 13, 2020, 12:42:44 pm
content: This seems to be a job rather for a modulation domain analyzer (MDO) than a scope. An MDO won't do eye diagrams, though. My favorite (second-hand only) and very affordable instument in this range is the HP 53310A. At times, it's possible to get it for so little money that it may be of interest even additionally to the scope. You may want to have a closer look at this type of instrument.Cheers,ThomasEdit:In order to be suit the higher frequency range (up to 2.5GHz), you've got to make sure that the 53310A contins option 31.

author: hpw
author_rank: Frequent Contributor
timestamp: October 13, 2020, 04:07:09 pm
content: >> It's forte is that it is affordable for a 2 GHZ sscope.the 8104 (1GHz BW) in single channel mode will go for 10 Gs. So the sample jitter spec will be a must have.If one could measure the reference 10MHz output, as I guess this is the master clock for the PLL to go upwards.So, the result of this 10Mhz Ref. would be interesting using 2 or different and better Histogram scopes as LeCroy SDA6040 with higher bits ADC's.I would like to analyze on 10Mhz..25MHz & 40kHz..2MHz clocks, the 20Hz....down to xx Milli Herz phase noise to view PN / jittery figures as single bell or dual bell figures.So as usual, best to have them on the personal bench before bay.Hp

author: hpw
author_rank: Frequent Contributor
timestamp: October 13, 2020, 07:50:43 pm
content: Some lights on this from Keysight Web:https://www.keysight.com/main/editorial.jspx?cc=ES&lc=eng&ckey=82148&nid=-11143.0.00&id=82148Read on : When measuring jitter with an oscilloscope it is important to be aware of the contribution to the measurement results of the test equipment.May the PicoScope 9000 series :https://www.picotech.com/oscilloscope/9300/picoscope-9300-sampling-oscilloscopesHp

author: hpw
author_rank: Frequent Contributor
timestamp: October 16, 2020, 11:26:09 am
content: Well,a DSO with 10G/s has a sample time of 100ps ... IMHO histogram's may work for larger jitter/PN as 1..10ns.In addition Rigol do not provide any information about the sample jitter (while based on 10Mhz PLL or may 10Mhz crystal low PN oscillator) and trigger jitter.In other words, to analyze 1ps PN / Jitter with DSO is today not possible!Hp

author: nctnico
author_rank: Super Contributor
timestamp: October 16, 2020, 03:54:12 pm
content: Quote from: hpw on October 16, 2020, 11:26:09 amThe spec to look for is trigger jitter. I suggest to look at oscilloscopes from Agilent/Keysight or Lecroy but still don't expect to get below a few tens of ps (peak to peak).

author: siggi
author_rank: Regular Contributor
timestamp: October 17, 2020, 09:37:52 pm
content: Quote from: nctnico on October 16, 2020, 03:54:12 pmMy venerable TDS784D has a trigger jitter spec of 7ps (typical), but only has 4GS/S sample rate max. It uses analog triggering, but it captures the time delta from trigger to the sample clock. This allows placing the captured record at sub-sample timing, such as e.g. in the equivalent time mode.

author: nctnico
author_rank: Super Contributor
timestamp: October 18, 2020, 11:15:46 am
content: Quote from: siggi on October 17, 2020, 09:37:52 pmThat is basically how all digital oscilloscopes work. The more modern ones analyse the waveform in the digital domain to determine the trigger point but in the end the result is the same. The samplerate doesn't really matter. That 7ps is likely RMS which doesn't tell you the nitty gritty of what the trigger jitter is peak-to-peak. For example: with the Agilent 54845A I used to own I could see 20ps time shifts without using averaging.