According to http://cp.literature.agilent.com/litweb/pdf/5989-8794EN.pdf
the real time sampling scope (like the TDS220 or TDS3012) can measure cycle to cycle jitter directly, whereas the equivalent time sampling has only one sample each trigger and a little delay on the sampling point for the next trigger. The displayed waveform is a sort of "sum" of more than one cycle and now I can't figure out what type of picture this can give. The TDS3012 has also the advantage of the Digital Phosphor behavior that can be useful for the jitter analysis. Maybe a stable timebase and low jitter external trigger input are essential. Unfortunately the TDS3012 has a 200ppm timebase... On Wed, Aug 22, 2012 at 2:54 PM, David <[email protected]> wrote: > Do you mean with a 7404 hex inverter? I actually did something like > this recently while adding a 75ns pre-trigger pulse to an existing > fast rise pulse generator. > > The pre-trigger pulse ended up having significant pattern dependant > jitter caused by the adjacent TTL divider chain modulating the supply > voltage and the poor power supply rejection of the 7404. I was easily > able to see the jitter on my 7T11 sampling oscilloscope but on my 2440 > (20 GS/sec equivalent time sampling), it was barely perceptible if > that despite ideal conditions. The peak to peak jitter was about > 100ps. > > As far as I could tell from the available online documentation, the > TDS220 and TDS3012 have relatively low sample rates and do not support > equivalent time sampling so I would expect them to show even less than > my 2440. > > On Wed, 22 Aug 2012 11:55:11 +0200, Azelio Boriani > <[email protected]> wrote: > > >In your opinion, if I build a 7404 ZCD and a hard limiter one, can I see > >the jitter difference on a simple 'scope (Tek TDS220 or TDS3012) or do I > >need the Wavecrest SIA3000? > > > >On Wed, Aug 22, 2012 at 1:37 AM, Bob Camp <[email protected]> wrote: > > > >> Hi > >> > >> Since the Collins approach "tunes" the system for a single frequency > input > >> (more or less), the approach is probably not the best for a "many > decades" > >> sort of frequency range. There are a number of things that he alludes > to in > >> the paper, but does not directly address. The most obvious is the > >> temperature dependance of the "stuff" the system is made of. Another is > the > >> simple fact that a non-clipping linear amplifier is likely the best > choice > >> for a first stage, provide the input is not already near clipping. > >> > >> Bob > >> > >> On Aug 21, 2012, at 12:50 PM, [email protected] wrote: > >> > >> > Hello everyone, > >> > > >> > I am new to this forum. > >> > It looks like a lively discussion on various topics. > >> > > >> > A colleague of mine here at Agilent pointed me to this paper entitled > >> "The Design of Low Jitter Hard Limiters" by Oliver Collins. In Bruce > >> Griffiths' precision time in frequency webpage, this paper is described > as > >> "seminal." > >> > (http://www.ko4bb.com/~bruce/ZeroCrossingDetectors.html) > >> > > >> > Since I'm trying to create a limiter that will accept frequencies > >> ranging from 1 MHz to 100 MHz, I thought it would be good to understand > the > >> conclusions of this paper (if not the mathematics as well). The > >> mathematics turned out to be quite challenging to decode. Has someone on > >> this forum unraveled the equations? It appears Collins has > recommendations > >> on the bandwidth and gain of a jitter minimizing limiter, and then > extends > >> this analysis to provide the bandwidth and gain of a cascade of > limiters. > >> But the application is still fuzzy. In figure 5, he shows a graph > showing > >> the dependence of jitter on crossing time. Is the crossing time > (implied > >> by equations 7) considered a design parameter one can vary? Also, on > figure > >> 4, the "k" parameter has been varied to show the rising waveform as a > >> function of "k". The threshold is always assumed to be 0.5. So could > "k" > >> be related to "tau", the time constant of the RC filter? > >> > > >> > Thanks in advance for all your help. > >> > > >> > Yours > >> > > >> > Raj > >> > > >> > > >> > > >> > _______________________________________________ > >> > time-nuts mailing list -- [email protected] > >> > To unsubscribe, go to > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> > and follow the instructions there. > >> > >> > >> _______________________________________________ > >> time-nuts mailing list -- [email protected] > >> To unsubscribe, go to > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> and follow the instructions there. > >> > >_______________________________________________ > >time-nuts mailing list -- [email protected] > >To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
