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How to tell? MMF or SMF

 
 
Katanga-Man
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      05-11-2004
Hi,
Slightly off topic but bear with me. Is there a simple way of telling
whether a fibre is single mode or multimode without having to wheel out the
TDR kit? SC or ST can't be it since they are applicable to either type. IS
there any quick way of finding out that anyone knows of?
Regards,
Steve


 
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Walter Roberson
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      05-11-2004
In article <7D4oc.84$AL1.4@newsfe1-win>, Katanga-Man <(E-Mail Removed)> wrote:
:Slightly off topic but bear with me. Is there a simple way of telling
:whether a fibre is single mode or multimode without having to wheel out the
:TDR kit? SC or ST can't be it since they are applicable to either type. IS
:there any quick way of finding out that anyone knows of?

The type and core size is usually printed on the cladding
And your SM would likely be thinner than your MM.

But if all you have available is a patch panel and you can't
see the fibre itself, time to break out the Fluke.
--
This is not the same .sig the second time you read it.
 
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Doug McIntyre
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      05-11-2004
"Katanga-Man" <(E-Mail Removed)> writes:
>Slightly off topic but bear with me. Is there a simple way of telling
>whether a fibre is single mode or multimode without having to wheel out the
>TDR kit? SC or ST can't be it since they are applicable to either type. IS
>there any quick way of finding out that anyone knows of?


It should be marked on the jacket or cladding.

If you have both sides unhooked, you could throw a fiber microscope on
it, and tell pretty much right away just by looking at the end. While
the cladding will be the same size on both, you'll be able to see the core
and what size it is.


--
Doug McIntyre http://www.velocityreviews.com/forums/(E-Mail Removed)
Network Engineer/Jack of All Trades
Vector Internet Services, Inc.
 
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Terry Baranski
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      05-11-2004
On Tue, 11 May 2004 02:35:09 +0100, "Katanga-Man" <(E-Mail Removed)>
wrote:

>Hi,
>Slightly off topic but bear with me. Is there a simple way of telling
>whether a fibre is single mode or multimode without having to wheel out the
>TDR kit? SC or ST can't be it since they are applicable to either type. IS
>there any quick way of finding out that anyone knows of?
>Regards,
>Steve
>


The jacket color may provide a clue. Orange tends to be multimode and
yellow tends to be singlemode.

-Terry
 
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Dmitri
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      05-17-2004
It is normally color of the cable's jacket as well as color of the (plastic
parts of) connectors that can tell the type of fiber:
The exception is hybrid (both MMF and SMF in the same jacket) cable, where
you are at mercy of the manufacturer to label it correctly. Sometimes with
hybrid cables the only way to tell (without actually rolling up the sleeves
and getting down and dirty with polished type connectors and a scope) is to
actually call the manufacturer and read them the marking of that cable.
If you are lucky, and you got indoor cables, then

SMF cables are yellow
MMF cables are orange, slate or even aqua (Avaya uses it for their 50/125um
stuff)
SM connectors have either white, blue or yellow booths. I've seen red as
well
MM connectors have beige, black or slate
green-colored connector usually denotes either APC (angle-polished
connector) or a reference cord
SMF connector adapters are usually blue
MMF connector adapters are usually beige

Good luck!


--
Dmitri Abaimov, RCDD
http://www.cabling-design.com
Cabling Forum, color codes, pinouts and other useful online resources for
premises wiring users and professionals
http://www.cabling-design.com/resour...sidential.html
Residential Cabling Guide



"Katanga-Man" <(E-Mail Removed)> wrote in message
news:7D4oc.84$AL1.4@newsfe1-win...
> Hi,
> Slightly off topic but bear with me. Is there a simple way of telling
> whether a fibre is single mode or multimode without having to wheel out

the
> TDR kit? SC or ST can't be it since they are applicable to either type.

IS
> there any quick way of finding out that anyone knows of?
> Regards,
> Steve
>
>
>




 
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Doug McIntyre
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      05-17-2004
"Dmitri <Cabling-Design.com>" <info@REMOVE_NO_SPAM_cabling-design.com> writes:
>It is normally color of the cable's jacket as well as color of the (plastic
>parts of) connectors that can tell the type of fiber:


Unless you get some of that really anoying fiber that is kind of
orange, but yet kind of yellow on the jacket, and no markings on the
jacket as to what it really was.

I did have to pull out the scope to make sure it was single-mode.
--
Doug McIntyre (E-Mail Removed)
Network Engineer/Jack of All Trades
Vector Internet Services, Inc.
 
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chris@nospam.com
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      05-18-2004
On 17 May 2004 21:30:43 GMT, Doug McIntyre <(E-Mail Removed)> wrote:

>"Dmitri <Cabling-Design.com>" <info@REMOVE_NO_SPAM_cabling-design.com> writes:
>>It is normally color of the cable's jacket as well as color of the (plastic
>>parts of) connectors that can tell the type of fiber:

>
>Unless you get some of that really anoying fiber that is kind of
>orange, but yet kind of yellow on the jacket, and no markings on the
>jacket as to what it really was.
>
>I did have to pull out the scope to make sure it was single-mode.



Or you ordered it in a non-typical color. For example, I have MM in
red, blue, and white outer jackets to segregate networks.

-Chris
 
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AnyBody43
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      05-18-2004
Doug McIntyre <(E-Mail Removed)> wrote in message news:<40a92f03$0$8511$(E-Mail Removed) >...
> "Dmitri <Cabling-Design.com>" <info@REMOVE_NO_SPAM_cabling-design.com> writes:
> >It is normally color of the cable's jacket as well as color of the (plastic
> >parts of) connectors that can tell the type of fiber:

>
> Unless you get some of that really anoying fiber that is kind of
> orange, but yet kind of yellow on the jacket, and no markings on the
> jacket as to what it really was.
>
> I did have to pull out the scope to make sure it was single-mode.


I have a fair bit of experience with fibre (in the UK) and
I have NEVER found the colour to be an indicator of the cable type.
Almost all of the installed stuff that I have seen was orange.

The cables have always been marked with the core diameter
which is usually marked as OuterDiameter/CoreDiameter. the marking
are pretty frequent along the fiber.

The numbers for single mode vary a wee bit but my understanding is
that this does not matter.

Note that in my experience the 50 and 62.5 MMF types do not
interoperate.

Sizes I think are specified in micro meters, 10E-6m.

125/62.5 MMF 62.5 core
125/50 MMF 50 core

125/9 SMF
125/8.5 SMF
125/8 SMF

Good luck.
 
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chris@nospam.com
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      05-19-2004
On 18 May 2004 02:22:57 -0700, (E-Mail Removed) (AnyBody43)
wrote:

>Doug McIntyre <(E-Mail Removed)> wrote in message news:<40a92f03$0$8511$(E-Mail Removed) >...
>> "Dmitri <Cabling-Design.com>" <info@REMOVE_NO_SPAM_cabling-design.com> writes:
>> >It is normally color of the cable's jacket as well as color of the (plastic
>> >parts of) connectors that can tell the type of fiber:

>>
>> Unless you get some of that really anoying fiber that is kind of
>> orange, but yet kind of yellow on the jacket, and no markings on the
>> jacket as to what it really was.
>>
>> I did have to pull out the scope to make sure it was single-mode.

>
>I have a fair bit of experience with fibre (in the UK) and
>I have NEVER found the colour to be an indicator of the cable type.
>Almost all of the installed stuff that I have seen was orange.
>
>The cables have always been marked with the core diameter
>which is usually marked as OuterDiameter/CoreDiameter. the marking
>are pretty frequent along the fiber.
>
>The numbers for single mode vary a wee bit but my understanding is
>that this does not matter.
>
>Note that in my experience the 50 and 62.5 MMF types do not
>interoperate.
>
>Sizes I think are specified in micro meters, 10E-6m.
>
>125/62.5 MMF 62.5 core
>125/50 MMF 50 core
>
>125/9 SMF
>125/8.5 SMF
>125/8 SMF
>
>Good luck.



In general, you can mix 50 and 62.5 MM, but you take roughly a 3dB hit
in power for each transition.

-Chris
 
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AnyBody43
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      05-19-2004
(E-Mail Removed) wrote in message

> >Note that in my experience the 50 and 62.5 MMF types do not
> >interoperate.


> In general, you can mix 50 and 62.5 MM, but you take roughly a 3dB hit
> in power for each transition.


Hmmm.

I only got involved with this once and the details are
now lost in the mists of time however I doubt that the
installation that I was working on would have been affected
by this power loss.

It was 100M Ethernet, and most likely used FDDI components,
over a few hundred meters with only a patch lead at each end.
There was no action until someone decided to
check the patch leads and found that we had a 50/62.5 missmatch.
Using matched ones fixed it.

Maybe all of the missmatched leads were duff, who knows or cares now.
 
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