1. Why LAN cabling
systems have to be certified?

There are
various factors that influence a growth of high performance LAN cabling.

- Legislation
requirements. Local area networks have to be certified prior they get
connected on the public communication network. Certification is performed
according to the relevant standard.

-
Demanding software
applications that carry simultaneous Audio, Video
and Data signals. Certification proves that the cable connection is suitable
for high speed data transmission.

-
Fast development of
Structured Cabling Systems. Structured Cabling
provides a reliable solution for clients with various independent communication
systems (computer network, phone line, alarm system, etc.) that work over the
same cable connection.

-
Environments with high influence
of electromagnetic interferences (EMI).

-
Compatibility issues. Various environments and applications should interact without
essential problems.

-
Advanced resource planning. All cabling systems should be designed and built in a way that
they remain useable and upgradeable within next 10 years.

Statistics have shown that
various cabling failures represent the major reason for malfunctioning in the
local area networks.

There are
different standards that determine how to design, build and verify LAN cabling
networks.

Which standard
to consider depends on the market and on the type of application which has to
run on a particular cabling network.

The most frequent
standards used for LAN cabling verification
are:

EN 50173: Information
technology – Generic cabling systems

ANSI/TIA/EIA-568-B: Commercial Building Telecommunications
Cabling Standard

ISO/IEC 11801: IT - Cabling for
customer premises

2. Which parameters have
to be measured?

q There are various parameters that have to be reported when the LAN
cabling certification is performed.

These
measurements in a certain way simulate conditions that happen in practice.

q
Signals that are sent along the
communication pair have maximum value 5V p-p, which means that every
interference from the adjacent pair or external electromagnetic interference
can essentially influence the transmitted signal.

q
Affected signals can result in
wrong data transmission, which can have detrimental effect on business
applications and other data-dependent systems.

q
Improper termination, excessive
lengths of cable segments and false grounding frequently contribute to a
negative end certification test.

• There are some typical measurements that are executed at LAN cabling
  certification process:

-        
Wire map, including shield
connection if present

-        
Cable segment length

-        
NEXT (Near End Crosstalk) loss,
pair-to-pair, measured from local-end

-        
NEXT loss, pair-to-pair,
measured from far-end; (Remote NEXT)

-        
NEXT loss, power sum, measured
from local-end; (PSNEXT)

-        
NEXT loss, power sum, measured
from far-end; (Remote PSNEXT)

-        
ELFEXT (Equalized Level
Crosstalk) measured from local-end

-        
ELFEXT (Equalized Level
Crosstalk) measured from far-end; (Remote ELFEXT)

-        
ELFEXT, power sum; (PS ELFEXT)

-        
ACR (Attenuation to Crosstalk
Ratio) measured from local-end

-        
Remote ACR (Attenuation to
Crosstalk Ratio) measured from far-end

-        
PSACR

-        
Remote PSACR

-        
Return loss, measured from
local end

-        
Return loss, measured from
far-end

-        
Propagation delay

-        
Delay skew

-        
DC resistance

-        
Attenuation

                     -      Characteristic impedance

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