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. 

 

Specialized Cabling Systems for Military Applications

April 6, 2017 at 8:00 AM

 

When you hear the word “military” you probably think of tanks, weapons and camouflage. Military communications and cabling systems may not be the first things that come to mind, but they certainly are an important part of military operations.

 

Cables being used in combat zones face more rigorous requirements than those used in everyday civilian applications. Military voice, video and data systems are designed for rapid deployment in harsh environments with exposure to extreme temperatures, shock, vibration, dust and moisture. Cables in these systems are also exposed to heavy EMI and RFI from motors, switching power supplies and nearby microprocessors, all of which can be detrimental to network performance.

 

These extreme conditions would render a commercial communications system useless, so combat-specialized infrastructure products have been designed to meet the needs of today’s combat-ready network systems.

 

Here are some examples of products and technologies designed to meet the needs of military communications networks.

 

Fiber Optics

 

By design fiber cables are immune to EMI and RFI sometimes encountered in the combat theatre. Additionally, fiber optic cables are now offered in special crush and impact-resistant designs and some military-styles are available with armored jacketed cable.

 

Connectors such as the Straight Tip (ST) are fitted with heavy tension springs to ensure proper mating when exposed to major shock and vibration. They are also offered with locking mechanisms for additional protection against optical disconnects.

 

Other fiber optic connectors for military applications feature Ingress Protection (IP) rated designs with screw lock mating and extra-strength strain reliefs of over 250 Newton’s to ensure a solid connection during field use.

 

Shielded Ethernet Cable

 

Shielded Cat5e or Cat6 copper cables are the way to go when fiber cabling isn’t an option. Military applications require shielded twisted pair (STP) copper cables and rugged military-style connectors for most applications. STP cabling reduces the damaging effects of EMI and RFI sometime encountered in the field.

 

Other Ethernet cabling options for military apps include IP68 rated cables that utilize ruggedized Anodized or Zinc Alloy finished connectors and double shielded, high-flex, UV and Oil resistant FR-TPE (Flame Retardant Thermoplastic Elastomer) jacket that is CMX outdoor rated to stand up to the toughest environments.

 

Jacket Compounds

 

Whether you’re using fiber or copper cables, the cable jacket compound should always be taken into consideration. The outer cable jacket of many copper and fiber cables is usually made of PVC material that is toxic when burned and can accelerate a fire spreading.

 

Low-smoke zero-halogen (LSZH) jackets are a much safer solution and a popular choice for military applications. As the name implies, LSZH cables produce minimal smoke and no halogen, both of which can be harmful to people and expensive communications equipment. LSZH cables will also self-extinguish which makes them ideal for enclosed spaces such as ships, aircraft, tanks and other vehicles.

 

Polyurethane jackets are sometimes used in military applications because of their ability to withstand damaging UV rays, oil and petroleum-based products, and mechanical abuse. Though cables with a Polyurethane jacket will also release toxic gases and will not self-extinguish like LSZH cables.

 

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