Gotta think of the Fourier series of the pulse. Yes group velocities or group
delay of the whole enchalada. It is all kinda the same thing. They were doing
some kind of soliton fiber development. Haven’t heard much for some time about
that. No idea how frequency pure/coherent the tx is. I imagine phase
coherency is a big deal.
From: Ken Hohhof
Sent: Wednesday, January 24, 2024 4:12 PM
To: 'AnimalFarm Microwave Users Group'
Subject: Re: [AFMUG] optical TX power levels
Looks like different wavelengths have different group velocities, so
compensation is possible (but probably not cheap?).
Is this because the transmitter doesn’t generate literally a single wavelength?
Or is this a WDM issue? Chuck says the pulses get smeared out in time, that
sounds like the first one.
From: AF <af-boun...@af.afmug.com> On Behalf Of Chuck McCown via AF
Sent: Wednesday, January 24, 2024 3:56 PM
To: AnimalFarm Microwave Users Group <af@af.afmug.com>
Cc: ch...@go-mtc.com
Subject: Re: [AFMUG] optical TX power levels
Yeah, the pulses tend to get smeared out in time if there is too much
dispersion. Similar to trying to use too high level of QAM with SNR issues.
From: Josh Luthman
Sent: Wednesday, January 24, 2024 12:26 PM
To: AnimalFarm Microwave Users Group
Subject: Re: [AFMUG] optical TX power levels
Even if the RX level is good?
> rx was within 0.3dBm on all 4 lanes on both sides
On Wed, Jan 24, 2024 at 1:22 PM Daniel Pautz via AF <af@af.afmug.com> wrote:
Yeah makes me think the two paths have different loss. We have had that on
mirrored paths, or even single paths with crappy splices on one of the
strands.
From: AF <af-boun...@af.afmug.com> On Behalf Of Chuck McCown via AF
Sent: Wednesday, January 24, 2024 11:12 AM
To: AnimalFarm Microwave Users Group <af@af.afmug.com>
Cc: ch...@go-mtc.com
Subject: Re: [AFMUG] optical TX power levels
Did anyone do dispersion testing on the fiber?
Chuck McCown
McCown Technology Corporation
8401 N Commerce Dr
Lake Point, Utah 84074
801-250-9503
435-830-4306 cell
www.mccowntech.com
www.microtrench-blades.com
www.terabitnetworks.com
From: Zach Underwood
Sent: Wednesday, January 24, 2024 12:07 PM
To: AnimalFarm Microwave Users Group
Subject: Re: [AFMUG] optical TX power levels
tired again this morning and still no link. rx was within 0.3dBm on all 4
lanes on both sides. We got 10gb 80km to link up. This will do for now. We will
be looking at getting 40gb 80km single lane optics or adding another site to
fiber loop to shorten the footage to under 40km.
On Wed, Jan 24, 2024 at 11:14 AM Colin Stanners <cstann...@gmail.com> wrote:
So both of those SFPs are within the tx power range.
100G may not work on a link that long unless you have dispersion
compensation fiber on the path or in a huge loop in a box style at one end.
You likely cannot change tx power levels on those SFPs, they will run at
the max they can do for that specific unit.
On Wed, Jan 24, 2024, 7:46 a.m. Zach Underwood <zunder1...@gmail.com> wrote:
TX Power 2~6.5dBm
I am struggling to get this 100gb link up. In the field this link is
quoted at 31 miles. The rx levels are -22 and -20 on both sides but I can't get
it to link. I take the same optics to the lab and add 20dbm of attenuator to
get almost the same rx levels as the field and it will link up.
I have added error-correction encoding reed-solomon per the user guide
for links over 40km.
So far I have not found a way to change the TX levels in arista, the
options are in the CLI but they dont seem to change the outcome. For me this is
the first time dealing with 80km optics or 100gb optics over 10km.
switch is Arista DCS-7060SX2-48YC6-R
https://resource.fs.com/mall/doc/20230531114903y4ljxw.pdf
https://www.fs.com/products/115818.html?attribute=29032&id=3462585
On Wed, Jan 24, 2024 at 8:35 AM Colin Stanners <cstann...@gmail.com>
wrote:
There should be. What does their datasheey indicate for tx power range?
On Wed, Jan 24, 2024, 7:31 a.m. Zach Underwood <zunder1...@gmail.com>
wrote:
Yep labels identical but there is a difference in default power
levels.
On Wed, Jan 24, 2024, 8:13 AM Mike Hammett <af...@ics-il.net> wrote:
Oh, meaning the variance between the two, otherwise identical
models?
-----
Mike Hammett
Intelligent Computing Solutions
Midwest Internet Exchange
The Brothers WISP
--------------------------------------------------------------------
From: "Zach Underwood" <zunder1...@gmail.com>
To: "AnimalFarm Microwave Users Group" <af@af.afmug.com>
Sent: Tuesday, January 23, 2024 12:51:39 PM
Subject: [AFMUG] optical TX power levels
I got 2x 100gb 80km optics from FS that run difficult default TX
power levels one is 3.81dBm and the other 2.63dBm, the config on the arista
devices hosting the optics is the same.
Has anyone seen much difference between optic like this? My sample
size is small due to the optices costing $4k each
--
Zach Underwood (RHCE,RHCSA,RHCT,UACA)
My website
advance-networking.com
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