Which is preferable for CATV deployment over GPON and why?

  What is difference between LC/APC connector and SC/APC connector? Which is preferable for CATV deployment over GPON and why? Please guide.

LC/APC and SC/APC connector

LC/APC and SC/APC connector

Actually depends on the equipment used for CATV

LC connector is smaller in diameter (1.5mm) than SC (2.5mm). The ONT side is generally SC type. At uplink for CATV, type of connector actually depends on the equipment used for CATV. These equipment may have LC or SC connector, varies from vendor to vendor.

For CATV deployment in GPON we use EDFA

for CATV deployment in GPON we use EDFA… to connect EDFA with the OLT we use SCAPC-SCAPC connector generally…. at the ONT end we also use SCAPC connector and from ONT to T.V we use normal coaxial cable.

How about in terms of connector loss?

Thanks for valuable guidance. My concerns are related to laser back reflection. Because if we need to deploy CATV over GPON, then we need to use APC. But in terms of connector loss, is their any difference between LC and SC connector type?

Hi, the difference between LC and SC lies in the size, the handling and the connector history. 

– Size:
LC is half the size of SC (actually, one SC-adapter is exactly the same size as a duplex LC-adapter), therefore LC is more and more common in central offices where packing density (number of connections per area) is an important cost factor.
– Handling:
SC is a true “push-pull-connector” and LC is a “latched connector” (although there are very innovative, real “push-pull-LCs” available which have the same handling capabilities like SC)
– Connector history:
the LC is the “younger” connector of the two, SC is wider spread around the world but LC is catching up.
Both connectors have the same Insertion Loss and Return Loss capabilities (these differ between suppliers but not because of the connector standard itself). Generally it depends where in the network you want to use the connectors, a connector in a Central Office (which is a professional environment with professional installers) has totally different needs than a connector in the end-users appartment.

To add some information about the difference on APC versus UPC

To add some information about the difference on APC versus UPC. You will notice that the connectors, whether they are SC or LC, will be color coded. Green connectors/bulkheads are for APC, while Blue connectors/bulkheads are for UPC.

However the main reason for APC, as far as RF overlay is concerned in PON deployments, is for back reflectance control. Once RF is introduced into the PON on the 1550nm wavelength, every bulkhead, split and splice introduces some amount of back reflectance. RF is not very tolerant of this. So APC is used to drive that reflectance at an angle into the cladding of the fiber instead of, essentially, a straight back reflectance. APC bulkheads also minimize “air gaps” between the 2 fibers connected to the bulkhead, which helps limit reflectance as well.

UPC on the other hand is for a mostly traditional data connection, since it is a lot more tolerant of back reflectance. Things like IPTV will not see a difference between APC or UPC connections as it is a data stream. This is why inside a central office you will see UPC/Blue connections between routers/switches/softswitches.

In most PON deployments that have an RF overlay, you will see that the OLT ports will be Blue for UPC connections with a fiber that heads over to a V-OLT that also has a Blue UPC connection. That V-OLT will also have a Green APC port for the video feed for ingress. Then there will be a Green APC port for egress into the PON splitter, since the V-OLT has combined the wavelengths from the “data” side and the “video” side together.
Hope this helps!

LC/APC and SC/APC in FTTH Cable operators CATV application

LC/APC and SC/APC in FTTH Cable operators CATV application

  “LC/APC is better than SC/apc because SC/APC Connector have high loss .5dB rether then LC/APC connector .3 dB”

All depends on the polishing procedure

All depens on the polishing procedure. On both connectors can achieve less than 0,5 or 0,3 db. The only difference between SC and LC is on the ferrule. The Ferrule on SC is 2,5mm and on the LC is 1,25 (half size of the SC).

Supplement on APC and UPC types connectors

There isn’t much difference in the performance between LC/APC and SC/APC. As Vishal mentioned earlier, the LC type is smaller in size and therefore more suitable on high density frames.
Regarding APC and UPC types, APC connectors are superior to UPC connectors in this performance category because of their angle-polished end face geometry. When light is reflected at the connector interface of a UPC connector, it is reflected straight back at the source, increasing the return loss value. However, when the same signal passes through the APC connector, the 8° angle causes the reflected light to be absorbed by the cladding material. UPC connectors are generally deployed in transport systems designed for digital signal transport, while APC connectors are preferred for RF video signal transport. The SC/APC type connector is currently a standard in both inside plant and outside plant applications.

 LC meet the need for high density connections

Above is right there. The LC exists because of the need for high density connections. I have found the LC with its 1.25 mm ferrule has slightly lower tolerances resulting in slightly lower losses on the APC and UPC.
While the SC is the standard I do believe the LC will overtake it quite soon.
We can achieve less than a .3 loss when doing an epoxy polish on either an APC or UPC LC connector.

One of the difference isthe security of the Fiber patching

There isn’t much difference except in the security of the Fiber patching. LC/APC is a latch on connector whereas SC/APC is a lock-on connector. SC/APC is basically to be used in places where the security of the fiber patching is of utmost importance(Therefore it the connector type that is utilised at the equipment side i.e. SFP). If you have space concerns in distribution boxes then it is better to Utilise LC/APC connector as SC/APC uses up more space. In fact you can have twice LC/APC connectors properly housed than SC/APC connectors

  “Yes. As friends and I suggested above. The LC connectors are more suitable and needed for High Density frames/connections.”

  “Another option for high-density, good performance connection is MU-type connectors. They are available with UPC or APC finish. “

LC type connector is compliant to Telcordia, EIA/TIA and IEC standards

Frineds above is right, The MU type connectors are small form and have similar performance, are suitable for high density connections. But they are NTT & JIS compliance and are mainly used in Japan.

The LC type connector is compliant to Telcordia, EIA/TIA and IEC standards and is widely used all over the world.

MU connectors originated in Japan

Dear team,
While MU connectors originated in Japan as you wrote, they have since migrated to other geographies; a good example is Scandinavia. And it is also very common to find MU connectors compliant to IEC, TIA or Telcordia standards (although not all vendors might have completed certification if they do not target US market for example).

LC is the most widely used SFF connector in the world

Reports suggest there are over 40,000,000 LC connectors in field use, making it the most widely used SFF connector in the world. LC interface is supported by a large number of manufacturers. The list of companies offering LC products in switches, routers, media converters, and other equipment is growing.
They are highly favoured for single mode applications and liked by users because of the familiar RJ-style latching. This makes the users comfortable with the LC, since its operation is the same as a modular plug and jack.


Recommend LC’s in the FTTH CO/HeadEnd, like FOT EDFA (above)

To answer the second half of the question, I would recommend LC’s in the CO/DataCenter/HeadEnd, to preserve space. As others have mentioned, the loss and performance of LC’s and SC’s are equilivant. You can specify different performance levels to hit your loss budget. In the OSP if you are going connectorized you may look at other connectors (SC or hardened SC / LC) as space is not as big of an issue and hand access is a bigger deal. (Glad to see you are going Angled, you don’t want to leave UPC’s open in most networks)

  “The ceramic ferrules on both connectors are identical and the connection loss for both types”

  “I think SC/APC is better its RL is better”

Discussions from linkedin.

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