Hi Hermann,
My CSA8200 is a sampling scope, and the sampling heads have 20 GHz bandwidth,
so I should have enough machine for this.
My goal is to produce a PAM-5 eye diagram with rise/fall times and/or a GbE
mask overlay:
http://www.kan.org/download/CSA8200Ethernet.png
Then I can experiment with terminating the pickoff legs, or leaving them open,
or changing the cable lengths if I leave them open, etc., and see how badly
those impact the eye opening.
I also want my engineers to put all 4 of those modules in my original photo
into a single, compact module with RJ45 in and out on one side, with the 8 SMA
pickoffs on the other. And compare the performance of that to this assembly.
And then do the same with 10GBaseT.
Thanks!
On Jun 20, 2020, at 11:30 PM, Hermann.Ruckerbauer@xxxxxxxxxxxxx
<Hermann.Ruckerbauer@xxxxxxxxxxxxx> wrote:
The mask is most likely only valid when a compliance Pattern is driven.
For Real waveforms you will not see a simple PAM, but 17 Levels due to
coding. At least this is what i remember. Should have some old Screenshots
somewhere.
I did this with a Realtime Scope, guess with setting a fixed frequency for
clock recovery.
Is your Tek Scope a Realtime or sampling Scope?
Just because i am curious: what is the target of your measurement?
Hermann
Am 20.06.2020 02:20 schrieb Steven Kan <steven@xxxxxxx>:
Apologies in advance if this is OT for this list:
I am trying to look at raw Ethernet waveforms on my oscilloscope, but I have
no idea how to set it up:
I have a pair of RJ45-to-SMA adapter boxes (PRL-RJ45-SMA) that allow me to
carry a set of Ethernet signals over eight 50 Ohm coax cables, and then
I���ve interrupted those 50 Ohm coax cables with a set of differential
pickoff boxes (PRL-860Q-SMA) that allow me to probe any pair with 10x
attenuation on the scope.
So the connection between the NIC and the switch looks like:
Cat5e���PRL-RJ45-SMA���8x0.5mCoax���2xPRL-860Q-SMA���8x0.5mCoax
PRL-RJ45-SMA���Cat5e
http://ftp.kan.org/download/PRL-RJ45-SMA_PRL-860Q-SMA.JPG
The chain of adapters and pickoffs seems to be ok, because I can successfully
carry Gigabit traffic over the link. I���ve tested two different NICs
into two different switches, and all combinations successfully negotiate a
Gigabit link, and iperf reports throughput of ~940 Mbit/sec for any/all
cases, which is the same as I get if I remove my gaggle of adapters and just
connect the NICs directly to the switch.
I have one differential pair from the pickoff going into my scope (CSA8200
with 80E04 sampling head), but I have no idea how to set up triggering, so
all I have is a cloud of dots :-)
If I go into the Trigger menu and choose Pattern Sync, it says
���Pattern Sync Module not available,��� but when I go to the
Mask menu, I can apply a Mask for Gigabit Ethernet.
Do I need to buy some sort of license module in order to trigger on Ethernet?
Or am I just doing it wrong?
I want to see PAM-5!!! And eventually I want to do this with 10GBaseT signals.
Thanks!
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