<mxshift>
He was stuck using an Agilent 90000 for that
<azonenberg>
mxshift: btw out of curiosity how did you like using the labmaster?
<azonenberg>
and were you mostly using probes or direct coax off test points or what?
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<mxshift>
Took a bit of learning to figure out the UI. Seems quite capable. Definitely slow when doing something like 25G NRZ jitter measurements over 4MS
<azonenberg>
If you can send over any huge files like that, i would love to compare the speed of glscopeclient
<azonenberg>
i'm not using exactly the same PLL they are
<azonenberg>
(although i plan to support the FC golden PLL soon)
<azonenberg>
but my general experience is that we're quite a bit faster for a lot of stuff
<mxshift>
We didn't have any way to include accessible tests points on the 100G lanes so we used a bunch of adapters to convert from our custom backplane cabling to the LabMaster inputs
<azonenberg>
Makes sense
<mxshift>
That 56G PAM capture is 4MS
<azonenberg>
ah ok, so i can play with it and see what i can do with the dataset then
<mxshift>
Yep, two single ended inputs for the diff channel
<mxshift>
Even without PLL, CTLE, FFE, PAM4 eyes should be okish
<azonenberg>
Two single ended inputs?
<azonenberg>
you only sent me channel 2 if the filename is correct
<azonenberg>
i don't think a .trc can store more than one channel
<mxshift>
We turned everything on and saw 7mV height and 6ps width
<mxshift>
Oh, I had a bunch of similar files. I can share the whole folder
<azonenberg>
if you can get me P and N from the same waveform that will make things much better
<azonenberg>
for the next half hour or so i'll be writing the importer so one file is enough
<azonenberg>
but to actually look at the data i need both halves
<azonenberg>
gonna do a bit more analysis on it, i'm curious how e.g. my jitter decomposition compares to the labmaster analysis (like i said we're using slightly different PLLs)
<mxshift>
I've got remote access to the labmaster if you want to see what it calculates for that same capture
<azonenberg>
yeah a screenshot with its analysis would be handy
<azonenberg>
i can probably load the .trc into my SDA and do the same analysis on it, but if you're all set up that would probably convenient
<mxshift>
what do you want to see?
<azonenberg>
whatever jitter parameters you want. I'm pulling up a jitter histogram, DDJ, DCD, ISI, p-p jitter
<azonenberg>
and a spectrum
<azonenberg>
(interesting, the jitter spectrum is acting up so i'll skip that)
<azonenberg>
ah ok, yeah that is probably one of the big reasons for the delta there
<mxshift>
we were tracking down low frequency jitter sources so settings evolved to find those and roughly reflect what we think Tofino2 is doing
<azonenberg>
yeah makes sense
<azonenberg>
yeah i'm really curious why my jitter spectrum tool choked on this capture
<azonenberg>
i'm gonna have to dig into that
<azonenberg>
it was outputting all zeroes
<azonenberg>
i've never seen that before
<mxshift>
I can give you an 80MS capture if you want a stress test
<azonenberg>
Sure
<azonenberg>
So it seems when i disable opencl acceleration, glscopeclient does a good jitter spectrum
<azonenberg>
(yet another reason to move away from CL, clFFT seems very buggy)
<monochroma>
D:
<azonenberg>
But it isn't showing much in the way of low frequency jitter. I think the transfer function of my CDR is such that most of that gets tracked rather than transferred
<mxshift>
Almost a mechanical package for your switch design
<azonenberg>
mxshift: cool. My first switch will be less fancy, 24x 1G interfaces plus a couple of 10G uplinks
<azonenberg>
But i've been keeping an eye on LDA's stuff on twitter etc
<azonenberg>
they have some pretty cool things,. including a host package that turns a VCU118 devkit into a switch breaking out all the serdes
<mxshift>
I find it interesting that are using Samtec ARC6. We're doing the same for our switch mainly for lower loss from front panel to ASIC
<azonenberg>
Nice. And yeah LDA's stuff is targeting HFT
<azonenberg>
so they have all kinds of industry specific features like constant latency from switch to any port
<azonenberg>
they claim <150ps skew between any set of ports
<mxshift>
yup, L1 port replication, etc
<azonenberg>
meanwhile i just want an open source switch fabric and dont need crazy performance
<azonenberg>
i just want a bunch of ports with wire speed nonblocking switching between them
<azonenberg>
plus basic management features like vlans, 802.1q, and forcing specific link speeds
<azonenberg>
anyway, the switch stuff has been on hold for a long time because i've had so many higher priority things to work on. like scopehal
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<mxshift>
apparently the QSGMII capture I sent you a while back might be inverted. In trying to debug things, one of my coworkers wrote a hacky decoder and replicated what you were seeing with D16.5. Inverting gives expected idle patterns.
<tiltmesenpai>
wow... that's definitely a switch...