CDNEXT (Near-End Xtalk de modo común a modo diferencial)

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CDNEXT (Common Mode to Differential Mode Near-End Xtalk) - DSX CableAnalyzer

CDNEXT is a troubleshooting tool only at this time for Channel Alien Xtalk testing issues. No hay límites de comprobación en ANSI/TIA-568-C.2, ANSI/TIA-1005 o ISO/IEC 11801:2010. However, you will find it discussed in TIA-TSB-1197.

Poor CDNEXT is primarily a connector choice issue. Although unlikley, it could be a workmanship issue too.

The measurement is made by injecting a differential mode signal (DM) into one twisted pair, then measuring the common mode signal (CM) on another pair. The smaller the CM signal returned, the better the CDNEXT.
             DSX CableAnalyzer Common Mode Measurement

If it looks similar to a NEXT measurement, you're right. Except a NEXT measurement is made by injecting a DM signal onto one pair and measuring the DM signal on another pair. Here we are measuring the CM signal on the other pair, which is CDNEXT.

Other balance measurements such as TCL, ELTCTL and CMRL are also available in the DSX-5000 CableAnalyzer.

If you wish to add CDNEXT to your standard Category 5e, 6, 6A or Class D, E or EA test, select your test limit with a suffix of (+ALL):
         Límite de comprobación para todas las categorías TIA     Límite de comprobación para todas las categorías ISO         

Esto aumentará su tiempo de PRUEBA AUTOMÁTICA.

The suffix of (+All) indicates a standard ANSI/TIA or ISO/IEC test with the addition of ELTCTLTCLResistance Unbalance within a pairResistance Unbalance between pairs, CMRL and CDNEXT measurements.
En el ejemplo a continuación de un DSX-5000 CableAnalyzer, un canal de la categoría 6A fue probado.
        Pantalla de equilibrio medición de DSX CableAnalyzer

Autor: Adrian Young

Creation Date: 2014-02-18

Last Modified: 2014-02-18

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