Can an Eye pattern be seen with a regualr scope? - Page 1
Forum section: electronics / projects

author: rbola35618
author_rank: Frequent Contributor
timestamp: April 11, 2013, 02:35:35 pm
content: Hi EEvblogger,I am an analog guy and don't know much about digital. My question is can a regular scope be used to display an eye pattern or do you need specialized equipment to perform that? If a regular scope can display an eye pattern, how do you hook it up and how do you set the scope?Bottom line, I am trying to measure the jitter of a High Voltage (0 to 500V) pulser and not quite sure how to measure the jitter. The pulse is being triggers by my Rigol function generator. I read somewhere that an eye pattern is used to measure the jitter. If there is another way of measuring jitter please let me know how.Robert

author: smashedProton
author_rank: Frequent Contributor
timestamp: April 11, 2013, 02:43:51 pm
content: Maybe a spectrum analayser woukd work. You could measure how wide tge fundamental is. My 2 cents

author: smashedProton
author_rank: Frequent Contributor
timestamp: April 11, 2013, 02:44:07 pm
content: Maybe a spectrum analayser woukd work. You could measure how wide tge fundamental is. My 2 cents

author: free_electron
author_rank: Super Contributor
timestamp: April 11, 2013, 02:45:01 pm
content: Put scope in infinite persistence.If you have an analog scope : bad luck , but you can still do it.. Put a polaroid camera on the scope, open shutter and let the scope write for a few seconds... You will have a co posite image.

author: jpb
author_rank: Super Contributor
timestamp: April 11, 2013, 02:51:50 pm
content: I was about to suggest what free_electron just suggested, i.e. get a composite image.One issue though is that most scopes would be unhappy with 500V so you presumably are going to feed it through some sort of attenuator.Eye diagrams are for examining data streams in telecoms I think (I'm not an expert), not really applicable to a simple pulse scheme.

author: rbola35618
author_rank: Frequent Contributor
timestamp: April 11, 2013, 02:58:36 pm
content: I forgot to mention that the pulse is 4us with a repetition rate of 2000 Hz. I do have the Rigol Spectrum Analyser. I had not thought about using the SA. So the bandwidth is the range that the jitter is changing the fundamental?Thanks you gentlemen. I'll see if I can use the SA to measure the jitter.Robert

author: muvideo
author_rank: Frequent Contributor
timestamp: April 11, 2013, 03:04:45 pm
content: Hello, if you want to measure the jitter between the trigger signaland the pulse output, then just trig the scope on the trigger signaland trace the pulse with the scope vertical input (using an adeguate probe, given the voltage).For triggering you can use external trigger input of the scope's timebase, if you have one working,i think it's mandatory for analogue scopes and fast signals.With a digital scope you can also use two channels, since it samples them at the same time.Like said free_electron, put the digital scope in infinite persistance.For analogue ones there are digital cameras

author: KJDS
author_rank: Super Contributor
timestamp: April 11, 2013, 03:56:24 pm
content: Quote from: rbola35618 on April 11, 2013, 02:58:36 pmThe jitter of a signal is an integral of the noise in the frequency domain. Use the trapezium rule and remember your analyzer has a log scale to confuse things. First measure a clean signal on your analyzer to determine measurement baseline.