NVP incorrectly set in tester - does it matter | Fluke Networks

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NVP incorrectly set in tester - does it matter

Do not get hung up on length, attenuation is the critical factor. Please read the following carefully.
  • The NVP of the cable can also vary in manufacturer by up to 2%.
  • The NVP setting affects the length measurement and NO other parameter.
  • The table below gives you an indication of the additional inaccuracy created on a maximum length with the incorrect setting for NVP.


Cable Length vs. NVP

Cable Length vs. NVP Report

If you have selected a TIA Standard, the length test will not fail until the prescribed length plus ten percent has been exceeded.
 
If you are measuring a Permanent Link which has a limit of 90 meters, the length test will not fail unless the measured length is greater than 99 meters (90 meters + 10%).

ANSI/TIA-1152
2.3.1 Physical length vs. electrical length
The pass or fail criteria is based on the maximum length allowed for the channel or permanent link as specified in ANSI/TIA-568-C.2 plus the nominal velocity of propagation (NVP) uncertainty of 10 %.
 
 
If you have selected an ISO or EN Standard, length is not required for compliance. You cannot therefore fail on length.
 
The active equipment is not concerned about the physical length, only that the attenuation, propagation delay and delay skew are within specification. This is why length is not a requirement in ISO/IEC 11801:2002.
  

From ISO/IEC 11801:2010:

Transmission parameter b

Testing for

Reference conformance testing

Installation conformance testing

Perda de retorno

N

N

Perda por inserção

N

N

Pair-to-pair NEXT

N

N

PS NEXT

C

C

Pair-to-pair ACR-N

C

N

PS ACR

C

C

Pair-to-pair ACR-F

N

N

PS ACR-F

C

C

Direct current (d.c.) loop resistance

N

N

Direct current (d.c.) resistance unbalance

N

I

Retardo de propagação

N

N

Desvio do retardo

N

N

Unbalance attenuation, near-end (TCL)

N

I

Unbalance attenuation, far-end (ELTCTL)

N

I

Coupling attenuation

N

I

PS ANEXT

N

NS

PS ANEXTavg

C

C

PS AACR-F

N

NS

PS AACR-Favg

C

C

Mapa de cabos

N

N

Continuity of conductors, screens (if applicable), short and open circuits

N

N

Lengtha

I

I

where
C is the calculated value;
I is the informative (optional) testing;
N is the normative (100 %) testing, if not met by design;
NS is the normative (sampled) testing, if not met by design. The sample size to
be tested should be in accordance with ISO/IEC 14763-2.

NOTE The term “met by design” refers to a requirement which may be met by the selection of appropriate materials and installation techniques.

a Length is not a pass/fail criterion.
b Only those parameters specified for each Class of cabling need to be tested, as required in Amendment 1:2008 and Annex A.

 
In Table B.1 above, the type of test to be carried out for each channel or permanent link is indicated by an "I" (informative) or "N" (normative). Parameters, which are computed from the measured parameters, are indicated by a "C". The tests indicated by I may be carried out as part of an acceptance test. The tests indicated by N shall be carried out as part of an acceptance, reference or compliance test.
 

Autor: Fluke Networks

Data de criação: 11-2-2014

Última alteração: 11-2-2014

 
 
 
 
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