Difference between LC/APC and SC/APC connector

Difference between LC/APC and SC/APC connector

What is difference between LC/APC connector and SC/APC connector?   Please guide.

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 handing 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 theOLT ports will be Blue for UPC connections with a fiber that heads over to a VOLT that also has a Blue UPC connection. That VOLT 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 VOLT has combined the wavelengths from the "data" side and the "video" side together. 

"LC/APC is better than SC/APC because SC/APC Connector have high loss .5 dB rather than LC/APC Connector .3 dB"

All depends 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. The LC type is smaller in size and therefore more suitable on high density frames. Regardign 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. 

View: www.fibercasa.com for more information