Cable Shielding Deciphered

June 1, 2017 at 8:00 AM

 

It’s no surprise that shielded cables are a hot topic, they can improve performance and are available in Cat5e, Cat6 and Cat6a and Cat7 versions. In past blog posts, we’ve talked about the advantages of shielded cables and how they protect from EMI/RFI and alien crosstalk (AXT). We’ve dug deeper to explore the different types of shielded cables and their benefits. We’ve even shown how to make your own shielded cable. Now, we’re going to take a closer look at the acronyms used to designate the different types of cable shielding and how to decipher them.

 

Cable shielding, also called screening, can be made of a metallic braid, or metallic or polyester foil. The shielding is either wrapped around all 4 pairs of twisted pair cable, just the individual conductor pairs, or both the entire cable and individual pairs.  In a shielded code, the letters before the slash designates the shielding on the entire cable; the code after the slash signifies shielding for the individual pairs.  For example:

 

Here is a glossary of terms to help you decode cable shielding:

 

 

FTP – Foiled Twisted Pair : An additional layer of protection is created with shielding/screening wrapped around the individual twisted wires. 

 

STP – Shielded Twisted Pair : Braided shielding wrapped around the individual twisted wires adds a layer of protection.

 

F/UTP – Foiled/Unshielded Twisted Pair : An overall foil shield encases the 4 pairs of unshielded twisted pair. Commonly used in 10GBaseT applications.


S/UTP – Shielded/Unshielded Twisted Pair :  An overall braid shield is wrapped around all 4 pairs of unshielded twisted pair.


SFTP – Shielded and Foiled Twisted Pair : Foil shielding around the individual twisted wires and an overall shield that is sometimes a flexible braided shield. This provides the highest level of protection from interference.

 

SF/UTP – Shielded and Foiled/Unshielded Twisted Pair : Both an overall braid screen and foil shield with unshielded twisted pairs. Occasionally referred to as an STP cable, these cables are very effective at protecting EMI/RFI from entering or exiting the cable.


S/FTP – Shielded Foiled/Twisted Pair : An overall braid shield with foil-shielded twisted pairs. The shield underneath the jacket is a braid and each individual pair is surrounded by its own foil shield. The purpose of the additional foil on individual pairs is to limit the amount of crosstalk between them.


F/FTP – Foiled/Foiled Twisted Pair : An overall foil shield with foil screened twisted pairs. Like F/UTP, this cable is commonly used in 10GBaseT applications.


U/FTP – Unshielded/Foiled Twisted Pair : No overall shielding or braid with foil-shielded twisted pairs. This cable is also frequently used in 10GBaseT applications.

 

U/UTP (UTP) – Unshielded/Unshielded Twisted Pair : Pairs of wires twisted together that are not shielded at all. These cables are often referred to as UTP andare one of the most basic methods used to help prevent electromagnetic interference. 

 

Everything you ever wanted to know about Category 8

February 23, 2017 at 8:00 AM

 

Category 8 is coming and we’re not taking about a torrential hurricane. This new standard for twisted-pair cabling is under development with ratification expected this year that will bring many exciting advancements in wired communications. Here is everything you need to know to prepare yourself for Category 8.

 

  -  Primarily intended to support 25GBASE-T and 40GBASE-T

 

  -  Different from previous standards because it uses 2000 MHz frequency

 

  -  Limited to 30 meter distance and 2-connector channels

 

  -  Ideal for data centers and small LANs in commercial buildings

 

  -  Targeted for use at the data center “edge” where connections are made between the server and switch

 

  -  Will be backward compatible with previous standards

 

  -  Two classes of products offered - Class I: RJ45 and Class II: Non-RJ45

 

  -  Requires shielded cable, but not limited to specific type of shielding. Can use F/UTP (8.1) or S/FTP (8.2) and other shielded constructions

 

  -  Can provide up to four times faster speeds on the same cabling being used today

 

  -  Exceptional signal-to-noise margin while supporting transmission rates of 25Gb/s and higher

 

  -  Connectors will be designed for field termination and also pre-terminated for Panduit’s QuickNet line

 

  -  Will allow data center designers to organize their racks and cabinets to support 30-meter channel connections now and be positioned to transfer to 25G/40GBASE-T when the technology becomes available

 

  -  Installation methods will be similar to lower grades of cabling. Can be installed in existing pathways and conduit, though to support 25GBASE-T and 40GBASE-T the existing infrastructure must be upgraded

 

  -  No additional power required. In fact, Cat8 may better support remote powering applications such as PoE because of its lower dc resistance and insertion loss. It is likely that 25GBASE-T and 40GBASE-T equipment will use more power than 10GBASE-T, but that may be remedied as the technology evolves

 

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