Looking for some guidance/references on the use of UPC versus APC terminations on fiber
cabling. Traditionally we have done all of our fiber plant targeting data usage with
UPC connectors. We are also looking at proposals for fiber distribution plant for
video, and the possibility of using some of the existing fiber plant for that purpose;
as well as any new fiber plant that gets installed for video potentially as data.
The video folks are set, determined, and insistent that they need APC terminations.
All data references I have found preach UPC. Cisco's SFP reference page even states (in
bold):
*Note:* Only connections with patch cords with PC or UPC connectors are supported.
Patch cords with APC connectors are not supported. All cables and cable assemblies
used must be compliant with the standards specified in the standards section.
So are we doomed to having physically separated fiber plants with suitable connectors /
jumpers dedicated to video? Anyone been down this snaky looking path?
Jeff
Remember - the nozzles on unleaded gas pumps aren't interchangeable with the
ones that dispense leaded gas (if any of those still exist?). Perhaps
somebody decided this was a good idea for video and data as well?
Where I work we maintain a mix of Telecom, Data, and CATV networking.
APC is REQUIRED per many manufacturers for video. It reduces reflections of the signal which in the video world can cause quite a few headaches and has the potential to have severe impact on video quality.
Also, if you're looking at GPON in the future, it also requires it.
We're staring to standardize on all-APC patch panels.
Cisco's SFP reference is not wrong. ONLY UPC is supported, but that is at the SFP interface. For us it means pre-ordering online quite a few LC/UPC -> SC/APC jumpers so we can interface with the patch panels.
So, Both are right. You could just as easily use APC for only video and keep all UPC for data and SONET. We just are going slowly to all APC to keep the management of spare parts easier.
Yes. Someone comes up with the brilliant idea to have APC on all new installs, people end up using UPC patch cables anyway, and mayhem ensues. You end up with having to stock substantially more patch cables than otherwise, because now you need LC/UPC-SC/UPC and LC/UPC-SC-APC, you need SC/APC-SC/APC, you need SC/UPC-SC/APC and so on. It's a mess.
If you need to do HFC in low-volume, do APC on those only. I believe it's going to be cheaper in the long run than trying to go APC everywhere.
If a majority is going to be HFC, then you might be better off to go APC everywhere.
Over the lifetime of this fiber plant, you will find yourself using
jumpers which convert to many different equipment-side connectors. So,
give the equipment side connectors a very low priority in your
equation and focus on capability. If you use APC terminations, can
jumper cables adequately convert them to UPC connectors on the
equipment side? Is the reverse true? That answer should drive your
choice.
Regards,
Bill Herrin
APC is pretty much the standard for high-power video distribution, and for very good reasons. The return loss is much better for APC than for UPC, for instance, and that can be very significant depending upon the equipment being used to drive. Much video distribution gear, including passive splitters and EDFA's, are only available with APC connectors.
Mating an APC to a UPC will result in an 'air-gap attenuator' being created, and that may be a problem. A significant problem for some gear, in fact.
Really high-power long-haul gear may need APC as well, even for networking stuff.
Your choice boils down to parallel plants or only APC with UPC jumpers for non-APC equipment. You really really don't want to have any UPC connectors in a really high-power path that needs APC all the way; I have actually seen some warranty statements, for some older equipment, primarily EDFA modules, that indicate that the warranty would be voided if any non-APC connectors were in the path anywhere. The reflections from a UPC end can detune some of these lasers, and can, in theory at least, cause permanent transmitter damage that won't be under warranty.
You could, though, provision half APC and half UPC, since the color coding is pretty clear. You can even use, say, all LC on your UPC patches and all SC on you APC patches or similar, and get both with little danger of intermating. I think I'd personally rather just provision all APC in the backbone fiber runs and install APC to UPC distribution runs to your network gear.
But you'll have to train people to always plug green connectors into green connectors, and blue into blue, and never should green and blue mix.
+1 here on going all APC on the panels, note we run a gpon network so
making that choice was fairly easy for us. You do end up having to use a
lot of sc or lc/upc - sc/apc patch cables on the colo equipment side of
things but everything out in the field is 100% sc/apc.
Carlos Alcantar
Race Communications / Race Team Member
1325 Howard Ave. #604, Burlingame, CA. 94010
Phone: +1 415 376 3314 / carlos@race.com / http://www.race.com