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Rhaas
Premium
join:2005-12-19
Bernie, MO

1 recommendation

reply to spectrumhead

Re: SFP module for 100km

That seems high to me, I assume that there may be some connectors (not splices) in there?

For us, we always estimate .3db loss per KM, +.1 per splice. We are always under the calculated loss.

Dont look at the advertised distance, that is just a rule of thumb. Look at the specs of the SFP.

The one you said you tried would obviously not work:

MAX Output power: +5 dbm
Minimum Recieve Sensitivity: -23

So that gives you ~28dbm of link loss, subtract 3 dbm for fade and you have 25dbm.

The JD103A May work (couldn't find HP's specs only a compatible)
MAX Output power: +5 dbm
Minimum Recieve sesnitivity: -32 dbm

So you should have ~35dbm to work with. *If the TX power is outputting at +5*

I gotta run, but that should be enough info to get you started in the right direction.
--
I survived Hale-Bopp!

spectrumhead

join:2009-05-03
Rhaas ;

According to the above info,

I found TN-SFP-LXB162 to have 37dbm link budget.

This is the most powerful that I could find.

Do you think it may work ?


Rhaas
Premium
join:2005-12-19
Bernie, MO
Based upon the numbers you posted above, then yes. That should give you ~5db of margin and should function without error.

I would add the caution of contacting the SFP manufacturer and getting their recomendation.

When testing the fiber you will want to shoot it with the same wavelength that you plan on using to light the path.
Just like wireless at different frequencies, different wavelengths will have different losses. Also, the fiber can be manufactured so that certain freqencies and will perform better at 1550nm rather than 1310nm or 1590nm. So if you didn't shoot the fiber, you need to know what wavelength they shot the fiber at.
--
I survived Hale-Bopp!


54067323

join:2012-09-25
Tuscaloosa, AL

1 recommendation

said by Rhaas:

When testing the fiber you will want to shoot it with the same wavelength that you plan on using to light the path.

I would add to that, with dark fiber, never trust the as-built, enough crap happens with lit fiber (which gets noticed) in the day to day maintenance and changes of the plant.

lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1
reply to Rhaas
said by Rhaas:

Just like wireless at different frequencies, different wavelengths will have different losses.

I just wanted to comment that typical single mode optical fibers are good for both 1300nm and 1500nm range.

This spec for some really old SM fiber. I drew the loss curve just to show loss gets lower from 1300nm towards 1500nm but there is a water absorption peak in the middle.

spectrumhead

join:2009-05-03
You guys are very helpful. thanks for all the great comments.

So while checking I found out that I might be wrong considering the wrong transition network SFP.

Instead of TN-SFP-LXB162 WDM , we should consider TN-SFP-LX16.
I think LX161 and 162 are used in pairs as they have different wavelengths per transmit/receive. Instead we have to consider LX16.

Datasheet :
For LX16
»www.transition.com/TransitionNet···plex.pdf

Am I right ? Could you please help me a bit more to finalize this problem.


lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1
Yes, you can use a single LX16 module on each side of the fiber since it has duplex LC connectors.


54067323

join:2012-09-25
Tuscaloosa, AL

1 edit
reply to Rhaas
Delete duplicate


54067323

join:2012-09-25
Tuscaloosa, AL
reply to Rhaas
said by Rhaas:

That seems high to me, I assume that there may be some connectors (not splices) in there?

That link is long for sure, is it a bs splice or a connector(s) who knows, heck there could be a couple of biconic's in that span.

Personally I would (if possible) kick it back to the who ever placed the fiber to begin with and an OTDR to locate the loss(s) and clear them, lacking that I would push for a larger light budget, that is if the SFP’s can handle those levels.

spectrumhead

join:2009-05-03
@MatrixHDV
LX16 has a linkbudget of 37db and manufacturer states that these values are with %10 over performance to secure the specifications.

Do you think that we should consider a higher link budget than LX16 ?


54067323

join:2012-09-25
Tuscaloosa, AL

1 edit
said by spectrumhead:

Do you think that we should consider a higher link budget than LX16 ?

Guess that depends on the cost as you can always pad the receive down, but if the fibers come up long you cannot gain up...