UNDERSTANDING CAT - 5 CABLES
Today's technology continues to promote convergence. Here in India, cable TV networks now often offer broadband internet connectivity through an extended LAN network more accurately, a Metropolitan Area Network (MAN). These networks must utilize CAT 5 cables as drop cables from the distribution outlet to the subscriber's computer. Thus, CAT 5 cables are now widely sold through CATV hardware retailers and purchased and deployed by Indian cable TV networks.
Let’s take a closer look at the CAT 5 cable. In UTP CABLE, UTP stands for "unshielded twisted pair." It is a cable type with one or more pairs of twisted insulated copper conductors contained in a single sheath. UTP cables are the most common type of cabling used in desktop computer applications. Unlike coaxial cables, the UTP cable has no shielding. The cable is not Coaxial, and simply consists of a bunch of twisted pairs of unshielded Cable, giving it its name. The twist in the cable plays a crucial role in the overall performance.
To begin with, what is this cabling called? Some call it "data/voice," some call it "low voltage," but most call it "Structured Cabling." It's the infrastructure for telephone and LAN connections in most commercial installations.
CAT 5 - The TWIST
UTP cable is manufactured in various categories. Each category indicates the performance capability of that cable. The word "Category" is abbreviated to "CAT". Hence Category 3 cable is CAT 3 cable and Category 5 cable is CAT 5 cable. CAT 5 refers to cables consisting of 4 Unshielded Twisted Pairs (UTP) of 24 AWG bare copper. The performance for these cables & connectors is specified up to 100 MHz and data rates of 100 Mbps.
The heart of CAT5 UTP cable comprises of four pairs of carefully twisted pairs of copper wire, insulated with carefully chosen thermoplastic insulation to provide high bandwidth, low attenuation, and low crosstalk. Low crosstalk ensures that signal leakage from one wire into the neighboring ones, is minimal. The secret ingredient of CAT 5 is the twists! To maintain CAT 5 performance, especially crosstalk, the twists must be maintained as close as possible to the connectors! The cable is terminated mostly in jacks, connector receptacles that have Punch-down terminations on the rear, and "tricks" inside to prevent crosstalk. As computer networks got faster, a need was felt for improved or enhanced CAT 5 cables. From this, emerged the CAT 5e specification.
Often referred to as addendum 5, Category 5 Enhanced (CAT-5e) was developed for simultaneous bi-directional transmission over 4-pairs. Both Category 5 and Category 5e consist of unshielded twisted pair with 100-ohm impedance. The bandwidth specifications of CAT 5 & CAT 5e are the same, 100 MHz. Improvements to Category 5 were made and additional electrical requirements such as power sum NEXT, equal level far-end crosstalk, power sum equal level far-end crosstalk, and return loss were added to create the 5e specification. Typical applications include those of Category 5 and full duplex encoding schemes such as gigabit Ethernet (1000 Base T).
CAT 5 & CAT 5E DIFFERENCE
The differences between Category 5 and Category 5e are in their transmission performance. Category 5e components are most suitable for a high-speed Gigabit Ethernet. While Category 5 components may function to some degree in a Gigabit Ethernet, they perform below standard during high-data transfer scenarios. To support Gigabit Ethernet, a higher performance version of CAT 5, enhanced CAT-5 or CAT-5e has been added to the standards. CAT 5e adds new performance requirements to permit higher speed network operation.
Parameter CAT 5 100 MHz CAT 5E 100 MHz
Attenuation 24.0dB 24.0dB
Next 27.1dB 30.1dB
Psnext N/A 27.1dB
Elfext 17.0dB 17.4dB
Pselefext 14.dB 14.4dB
ACR (derived) 3.1dB 6.1dB
PSACR(derived) N/A 3.1dB
Return Loss 8.0dB 10.0dB
NON STANDARD CAT-7
And today, vendors are hyping CAT 6 and a ton of higher performance cable options. CAT 6 standards have been established, but CAT 7 is not yet standardized, and investing in them today could be a total waste of money, depending on how the standards committees go. You are probably better off saving your money and investing time in installing CAT 5 properly. Even better, consider optical fiber if higher performance is your goal. However, for LAN delivery of Internet, as used in India, it is economically unviable to offer huge Internet bandwidth at less than Rs 1000 per month per subscriber. Hence CAT 5 cable is more than adequate for the task. Even CAT 5e is quite unnecessary.