Re: [AFMUG] optical TX power levels

[dmmoffett]

As an OTDR trace it looks really good, but your problem might be at event 18 
and/or 19.   I don’t know how much you wanted to know so I apologize if I’m 
starting too far towards the beginning.

 

#18 is around 100m from the end and has reflectance of -21.36.  That’s crappy.  

The -15 below it is even crappier.

 

A UPC connector should be -40 to -50 dB

An APC connector should be better than -55 or -60 depending on who you believe. 

 

If the distance is correct then maybe #18 is a cross connect panel?  #19 should 
be your Arista.  Start with re-cleaning those connectors.  One-click cleaners 
are fast and cheap.  They only shot this in one direction, so we don’t know 
about the connectors on the other end.  I’d clean it on both sides.

 

The line graph is showing you attenuation over distance.  You’re averaging 
under 0.2dB per Km so that’s really good.  The table below is showing you 19 
events.  An event is any point along the graph where attenuation suddenly 
increased.  Events are either “reflective” or “non-reflective”.  In the first 
column of the table they’re showing you a /R or /N for reflective or 
non-reflective.  You can also tell that in the line graph because reflective 
events will have a spike before the dip. You don’t want reflections.  
Reflections are given in a -dB and you want it farther from zero (i.e.: -55 
reflectance is better than -40 reflectance).

 

(And side comment: reflectance is the same thing as return loss, but in optics 
people seem to prefer the term “reflectance”.  The only difference is return 
loss should be indicated with a positive number and reflectance is negative.  

Return Loss = 10*log(incident power/reflected power) in +dB

   Reflectance = 10*log(reflected power/incident power) in -dB

)

 

Non-reflective events are things adding attenuation but not adding reflectance. 
 Those would be fusion splices, coils, and bends.  

 

Reflective events mean there’s an exposed face of glass.  Those would be 
mechanical splices or connectors.  Reflective events could also be a fault in 
the fiber like a bubbled fusion splice.  

 

All that noise at the end of the line shows where the dead end is.

 

On that test result the only event I don’t like along the middle of the run is 
#9.  4dB is a lot for one event.  It might be a less than perfect splice, a 
tight bend in a splice tray, a slack coil that’s too tight, or whatever.  It’s 
not enough to ruin this link, and it’s probably ok if it stays at 4dB forever.  
There are some underground cases where I’ve seen the same high attenuation 
events for years, but they’re not hurting us and it’s too much trouble to 
access the case to fix something that isn’t currently a problem.

 

If nobody ever said this before: you should clean connectors every time they 
are handled.  No matter what anybody tells you, the caps they come with are not 
“dust caps” and they won’t keep it clean; the caps are there so the glass face 
doesn’t get scratched.  When I’m plugging things in I clean the jack, clean the 
plug, and then treat it like I’m playing the old Operation game:  If the 
ferrule touches anything before it goes into the hole then it’s “Bzt!” and 
reclean it.

 

The dispersion thing is a new concept for me, and I don’t think you could 
diagnose it from this one trace.  From what I’m gathering in this thread, I 
think you’d have to shoot it on multiple wavelengths and compare the 
differences.  This trace is only at 1550nm.  

 

-Adam

 

 

 

From: AF  On Behalf Of Zach Underwood
Sent: Wednesday, January 24, 2024 7:41 PM
To: AnimalFarm Microwave Users Group 
Subject: Re: [AFMUG] optical TX power levels

 

Ok we got the report back from the fiber supplier. This is new to me so anyone 
can offer insight into it?

 

PDF 
https://drive.google.com/file/d/1KeIuWHFsiKZHxcmpPiY8PX_-PABl55Sz/view?usp=sharing
 

 

On Wed, Jan 24, 2024 at 6:00 PM Daniel Pautz via AF mailto:af@af.afmug.com> > wrote:

Dispersion compensation module - https://www.fs.com/products/65783.html

 

From: AF mailto:af-boun...@af.afmug.com> > On Behalf 
Of Ken Hohhof
Sent: Wednesday, January 24, 2024 3:53 PM
To: 'AnimalFarm Microwave Users Group' mailto:af@af.afmug.com> >
Subject: Re: [AFMUG] optical TX power levels

 

I spent a few minutes searching on the term DCM and came up with “chirped fiber 
Bragg grating”.

https://en.wikipedia.org/wiki/Fiber_Bragg_grating

 

OK, I’m out of my depth now.

 

 

From: AF mailto:af-boun...@af.afmug.com> > On Behalf 
Of Daniel Pautz via AF
Sent: Wednesday, January 24, 2024 4:40 PM
To: AnimalFarm Microwave Users Group mailto:af@af.afmug.com> >
Cc: Daniel Pautz mailto:d...@webnx.com> >
Subject: Re: [AFMUG] optical TX power levels

 

Perhaps pick up a used cheap DCM and see if it helps,  adjustable  preferred if 
not as close to the fiber distance.   Our newest 100G dwdm build (dozen 100G 
optics) very much needed a DCM on it.   

 

From: AF mailto:af-boun...@af.afmug.com> > On Be

Re: [AFMUG] optical TX power levels

[Zach Underwood]

wow thanks for the detail, I will work with the boss and the fiber provider
to try to address some of those problems.

On Thu, Jan 25, 2024 at 10:14 AM  wrote:

> As an OTDR trace it looks really good, but your problem might be at event
> 18 and/or 19.   I don’t know how much you wanted to know so I apologize if
> I’m starting too far towards the beginning.
>
>
>
> #18 is around 100m from the end and has reflectance of -21.36.  That’s
> crappy.
>
> The -15 below it is even crappier.
>
>
>
> A UPC connector should be -40 to -50 dB
>
> An APC connector should be better than -55 or -60 depending on who you
> believe.
>
>
>
> If the distance is correct then maybe #18 is a cross connect panel?  #19
> should be your Arista.  Start with re-cleaning those connectors.  One-click
> cleaners are fast and cheap.  They only shot this in one direction, so we
> don’t know about the connectors on the other end.  I’d clean it on both
> sides.
>
>
>
> The line graph is showing you attenuation over distance.  You’re averaging
> under 0.2dB per Km so that’s really good.  The table below is showing you
> 19 events.  An event is any point along the graph where attenuation
> suddenly increased.  Events are either “reflective” or “non-reflective”.
> In the first column of the table they’re showing you a /R or /N for
> reflective or non-reflective.  You can also tell that in the line graph
> because reflective events will have a spike before the dip. You don’t want
> reflections.  Reflections are given in a -dB and you want it farther from
> zero (i.e.: -55 reflectance is better than -40 reflectance).
>
>
>
> (And side comment: reflectance is the same thing as return loss, but in
> optics people seem to prefer the term “reflectance”.  The only difference
> is return loss should be indicated with a positive number and reflectance
> is negative.
>
> Return Loss = 10*log(incident power/reflected power) in +dB
>
>Reflectance = 10*log(reflected power/incident power) in -dB
>
> )
>
>
>
> Non-reflective events are things adding attenuation but not adding
> reflectance.  Those would be fusion splices, coils, and bends.
>
>
>
> Reflective events mean there’s an exposed face of glass.  Those would be
> mechanical splices or connectors.  Reflective events could also be a fault
> in the fiber like a bubbled fusion splice.
>
>
>
> All that noise at the end of the line shows where the dead end is.
>
>
>
> On that test result the only event I don’t like along the middle of the
> run is #9.  4dB is a lot for one event.  It might be a less than perfect
> splice, a tight bend in a splice tray, a slack coil that’s too tight, or
> whatever.  It’s not enough to ruin this link, and it’s probably ok if it
> stays at 4dB forever.  There are some underground cases where I’ve seen the
> same high attenuation events for years, but they’re not hurting us and it’s
> too much trouble to access the case to fix something that isn’t currently a
> problem.
>
>
>
> If nobody ever said this before: you should clean connectors every time
> they are handled.  No matter what anybody tells you, the caps they come
> with are not “dust caps” and they won’t keep it clean; the caps are there
> so the glass face doesn’t get scratched.  When I’m plugging things in I
> clean the jack, clean the plug, and then treat it like I’m playing the old
> Operation game:  If the ferrule touches anything before it goes into the
> hole then it’s “Bzt!” and reclean it.
>
>
>
> The dispersion thing is a new concept for me, and I don’t think you could
> diagnose it from this one trace.  From what I’m gathering in this thread, I
> think you’d have to shoot it on multiple wavelengths and compare the
> differences.  This trace is only at 1550nm.
>
>
>
> -Adam
>
>
>
>
>
>
>
> *From:* AF  *On Behalf Of *Zach Underwood
> *Sent:* Wednesday, January 24, 2024 7:41 PM
> *To:* AnimalFarm Microwave Users Group 
> *Subject:* Re: [AFMUG] optical TX power levels
>
>
>
> Ok we got the report back from the fiber supplier. This is new to me so
> anyone can offer insight into it?
>
>
>
> PDF
> https://drive.google.com/file/d/1KeIuWHFsiKZHxcmpPiY8PX_-PABl55Sz/view?usp=sharing
>
>
>
>
> On Wed, Jan 24, 2024 at 6:00 PM Daniel Pautz via AF 
> wrote:
>
> Dispersion compensation module - https://www.fs.com/products/65783.html
>
>
>
> *From:* AF  *On Behalf Of *Ken Hohhof
> *Sent:* Wednesday, January 24, 2024 3:53 PM
> *To:* 'AnimalFarm Microwave Users Group' 
> *Subject:* Re: [AFMUG] optical TX power levels
>
>
>
> I spent a few minutes searching on the term DCM and came up with “chirped
> fiber Bragg grating”.
>
> https://en.wikipedia.org/wiki/Fiber_Bragg_grating
>
>
>
> OK, I’m out of my depth now.
>
>
>
>
>
> *From:* AF  *On Behalf Of *Daniel Pautz via AF
> *Sent:* Wednesday, January 24, 2024 4:40 PM
> *To:* AnimalFarm Microwave Users Group 
> *Cc:* Daniel Pautz 
> *Subject:* Re: [AFMUG] optical TX power levels
>
>
>
> Perhaps pick up a used cheap DCM and see if it helps,  adjus

Re: [AFMUG] optical TX power levels

[dmmoffett]

Out of curiosity, what did the provider tell you about this trace?  The -20 and 
-15 reflectance stand out pretty loud and clear.  If their OTDR has a “smart” 
mode it would have flagged those as failures.  If they didn’t see a problem 
here they might need a test device smarter than they are.

 

 

From: AF  On Behalf Of Zach Underwood
Sent: Thursday, January 25, 2024 10:26 AM
To: AnimalFarm Microwave Users Group 
Subject: Re: [AFMUG] optical TX power levels

 

wow thanks for the detail, I will work with the boss and the fiber provider to 
try to address some of those problems.

 

On Thu, Jan 25, 2024 at 10:14 AM mailto:dmmoff...@gmail.com> > wrote:

As an OTDR trace it looks really good, but your problem might be at event 18 
and/or 19.   I don’t know how much you wanted to know so I apologize if I’m 
starting too far towards the beginning.

 

#18 is around 100m from the end and has reflectance of -21.36.  That’s crappy.  

The -15 below it is even crappier.

 

A UPC connector should be -40 to -50 dB

An APC connector should be better than -55 or -60 depending on who you believe. 

 

If the distance is correct then maybe #18 is a cross connect panel?  #19 should 
be your Arista.  Start with re-cleaning those connectors.  One-click cleaners 
are fast and cheap.  They only shot this in one direction, so we don’t know 
about the connectors on the other end.  I’d clean it on both sides.

 

The line graph is showing you attenuation over distance.  You’re averaging 
under 0.2dB per Km so that’s really good.  The table below is showing you 19 
events.  An event is any point along the graph where attenuation suddenly 
increased.  Events are either “reflective” or “non-reflective”.  In the first 
column of the table they’re showing you a /R or /N for reflective or 
non-reflective.  You can also tell that in the line graph because reflective 
events will have a spike before the dip. You don’t want reflections.  
Reflections are given in a -dB and you want it farther from zero (i.e.: -55 
reflectance is better than -40 reflectance).

 

(And side comment: reflectance is the same thing as return loss, but in optics 
people seem to prefer the term “reflectance”.  The only difference is return 
loss should be indicated with a positive number and reflectance is negative.  

Return Loss = 10*log(incident power/reflected power) in +dB

   Reflectance = 10*log(reflected power/incident power) in -dB

)

 

Non-reflective events are things adding attenuation but not adding reflectance. 
 Those would be fusion splices, coils, and bends.  

 

Reflective events mean there’s an exposed face of glass.  Those would be 
mechanical splices or connectors.  Reflective events could also be a fault in 
the fiber like a bubbled fusion splice.  

 

All that noise at the end of the line shows where the dead end is.

 

On that test result the only event I don’t like along the middle of the run is 
#9.  4dB is a lot for one event.  It might be a less than perfect splice, a 
tight bend in a splice tray, a slack coil that’s too tight, or whatever.  It’s 
not enough to ruin this link, and it’s probably ok if it stays at 4dB forever.  
There are some underground cases where I’ve seen the same high attenuation 
events for years, but they’re not hurting us and it’s too much trouble to 
access the case to fix something that isn’t currently a problem.

 

If nobody ever said this before: you should clean connectors every time they 
are handled.  No matter what anybody tells you, the caps they come with are not 
“dust caps” and they won’t keep it clean; the caps are there so the glass face 
doesn’t get scratched.  When I’m plugging things in I clean the jack, clean the 
plug, and then treat it like I’m playing the old Operation game:  If the 
ferrule touches anything before it goes into the hole then it’s “Bzt!” and 
reclean it.

 

The dispersion thing is a new concept for me, and I don’t think you could 
diagnose it from this one trace.  From what I’m gathering in this thread, I 
think you’d have to shoot it on multiple wavelengths and compare the 
differences.  This trace is only at 1550nm.  

 

-Adam

 

 

 

From: AF mailto:af-boun...@af.afmug.com> > On Behalf 
Of Zach Underwood
Sent: Wednesday, January 24, 2024 7:41 PM
To: AnimalFarm Microwave Users Group mailto:af@af.afmug.com> >
Subject: Re: [AFMUG] optical TX power levels

 

Ok we got the report back from the fiber supplier. This is new to me so anyone 
can offer insight into it?

 

PDF 
https://drive.google.com/file/d/1KeIuWHFsiKZHxcmpPiY8PX_-PABl55Sz/view?usp=sharing
 

 

On Wed, Jan 24, 2024 at 6:00 PM Daniel Pautz via AF mailto:af@af.afmug.com> > wrote:

Dispersion compensation module - https://www.fs.com/products/65783.html

 

From: AF mailto:af-boun...@af.afmug.com> > On Behalf 
Of Ken Hohhof
Sent: Wednesday, January 24, 2024 3:53 PM
To: 'AnimalFarm Microwave Users Group' mailto:af@af.afmug.com> >
Subject: Re: [AFMUG] optical TX power le

Re: [AFMUG] optical TX power levels

[Trey Scarborough]

Ive done a lot of these 100G 80k links and its not likely dispersion 
causing your problem. Its more likely the opposite. If you have segments 
of NZ fiber "Non-zero dispersion-shifted fiber" you can have issues. 
After looking at your OTDR it looks to be a mix of different fiber types 
thats how you get the negative loss splices. If it is a mix of NZ and 
smf28 fiber your probably not going to be able to get it to work. The NZ 
fiber causes issues with the 1200-1300 signals on those optics. I have 
had spans of 50k that 80k optics would not work on due to this. I would 
have them run an OTDR at 1310 and see what it shows you are likely to 
get a very different looking result. If that's the case there aren't too 
many good options. Your best is if your switch has 400g ports get some 
OpenZR 400G optics and use them. Surprisingly that aren't incredibly 
more expensive than the 100G 80ks.


I would have the fiber provider give you a 1310 OTDR and also request 
fiber type information for the span. We build these things all the time 
so if you need some help feel free to email me and I can see about 
finding a solution that will work for you.


On 1/24/24 6:40 PM, Zach Underwood wrote:
Ok we got the report back from the fiber supplier. This is new to me 
so anyone can offer insight into it?


PDF 
https://drive.google.com/file/d/1KeIuWHFsiKZHxcmpPiY8PX_-PABl55Sz/view?usp=sharing 



On Wed, Jan 24, 2024 at 6:00 PM Daniel Pautz via AF > wrote:


Dispersion compensation module -
https://www.fs.com/products/65783.html

*From:*AF mailto:af-boun...@af.afmug.com>> *On Behalf Of *Ken Hohhof
*Sent:* Wednesday, January 24, 2024 3:53 PM
*To:* 'AnimalFarm Microwave Users Group' mailto:af@af.afmug.com>>
*Subject:* Re: [AFMUG] optical TX power levels

I spent a few minutes searching on the term DCM and came up with
“chirped fiber Bragg grating”.

https://en.wikipedia.org/wiki/Fiber_Bragg_grating

OK, I’m out of my depth now.

*From:*AF mailto:af-boun...@af.afmug.com>> *On Behalf Of *Daniel Pautz via AF
*Sent:* Wednesday, January 24, 2024 4:40 PM
*To:* AnimalFarm Microwave Users Group mailto:af@af.afmug.com>>
*Cc:* Daniel Pautz mailto:d...@webnx.com>>
*Subject:* Re: [AFMUG] optical TX power levels

Perhaps pick up a used cheap DCM and see if it helps, adjustable 
preferred if not as close to the fiber distance.   Our newest 100G
dwdm build (dozen 100G optics) very much needed a DCM on it.

*From:*AF mailto:af-boun...@af.afmug.com>> *On Behalf Of *Chuck McCown via AF
*Sent:* Wednesday, January 24, 2024 3:36 PM
*To:* 'AnimalFarm Microwave Users Group' mailto:af@af.afmug.com>>
*Cc:* ch...@go-mtc.com 
*Subject:* Re: [AFMUG] optical TX power levels

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 mailto: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 mailto: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
mailto: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 mailto: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 mailto:af@af.afmug.com>>
*Cc:* ch...@go-mtc.com 
*Subject:* Re: [AFMUG] optical TX power levels

Re: [AFMUG] optical TX power levels

[Chuck McCown via AF]

Could he bond dwm multiples at lower rates?

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: Trey Scarborough 
Sent: Thursday, January 25, 2024 5:00 PM
To: af@af.afmug.com 
Subject: Re: [AFMUG] optical TX power levels

Ive done a lot of these 100G 80k links and its not likely dispersion causing 
your problem. Its more likely the opposite. If you have segments of NZ fiber 
"Non-zero dispersion-shifted fiber" you can have issues. After looking at your 
OTDR it looks to be a mix of different fiber types thats how you get the 
negative loss splices. If it is a mix of NZ and smf28 fiber your probably not 
going to be able to get it to work. The NZ fiber causes issues with the 
1200-1300 signals on those optics. I have had spans of 50k that 80k optics 
would not work on due to this. I would have them run an OTDR at 1310 and see 
what it shows you are likely to get a very different looking result. If that's 
the case there aren't too many good options. Your best is if your switch has 
400g ports get some OpenZR 400G optics and use them. Surprisingly that aren't 
incredibly more expensive than the 100G 80ks. 


I would have the fiber provider give you a 1310 OTDR and also request fiber 
type information for the span. We build these things all the time so if you 
need some help feel free to email me and I can see about finding a solution 
that will work for you.



On 1/24/24 6:40 PM, Zach Underwood wrote:

  Ok we got the report back from the fiber supplier. This is new to me so 
anyone can offer insight into it? 

  PDF 
https://drive.google.com/file/d/1KeIuWHFsiKZHxcmpPiY8PX_-PABl55Sz/view?usp=sharing
 

  On Wed, Jan 24, 2024 at 6:00 PM Daniel Pautz via AF  wrote:

Dispersion compensation module - https://www.fs.com/products/65783.html



From: AF  On Behalf Of Ken Hohhof
Sent: Wednesday, January 24, 2024 3:53 PM
To: 'AnimalFarm Microwave Users Group' 
Subject: Re: [AFMUG] optical TX power levels



I spent a few minutes searching on the term DCM and came up with “chirped 
fiber Bragg grating”.

https://en.wikipedia.org/wiki/Fiber_Bragg_grating



OK, I’m out of my depth now.





From: AF  On Behalf Of Daniel Pautz via AF
Sent: Wednesday, January 24, 2024 4:40 PM
To: AnimalFarm Microwave Users Group 
Cc: Daniel Pautz 
Subject: Re: [AFMUG] optical TX power levels



Perhaps pick up a used cheap DCM and see if it helps,  adjustable  
preferred if not as close to the fiber distance.   Our newest 100G dwdm build 
(dozen 100G optics) very much needed a DCM on it.   



From: AF  On Behalf Of Chuck McCown via AF
Sent: Wednesday, January 24, 2024 3:36 PM
To: 'AnimalFarm Microwave Users Group' 
Cc: ch...@go-mtc.com
Subject: Re: [AFMUG] optical TX power levels



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  On Behalf Of Chuck McCown via AF
Sent: Wednesday, January 24, 2024 3:56 PM
To: AnimalFarm Microwave Users Group 
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  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  On Behalf Of Chuck McCown via AF
  Sent: Wednesday, January 24, 2024 11:12 AM
  To: AnimalFarm Microwave Users Group 
  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