Fluke DSX-8000 - Db Rule

Versiv Series Cabling Certification Product Family
Technical Reference Handbook
152
3 dB Rule
At frequencies where insertion loss is less than 3.0 dB for a pair,
return loss for that pair is not evaluated against a limit. See Tables
4 and 5 for applicable limits.
4 dB Rule
This rule applies to these ISO limits:
 ISO/IEC 11801
 EN 50173
 Aus/NZ
 JIS
At frequencies where insertion loss is less than 4.0 dB for the pair
used as the receive pair for the test, the measurements shown in
Table 5 are not evaluated against a limit.
12 dB Rule
This rule applies to these ISO test limits:
 ISO11801 Channel Class E
A
 ISO11801 PL Class E
A
If insertion loss at 450 MHz is less than 12 dB for both pairs, the
tester uses a relaxed limit for NEXT. If the standard and relaxed
limits both apply to a plot, the plot shows both limit lines. See the
Knowledge Base on the Fluke Networks website for details.
15 dB Rule
This rule applies to these ISO test limits:
 ISO11801 PL Class I
 ISO11801 PL Class II
If insertion loss at 1,600 MHz is less than 15 dB, the tester uses
alternate return loss limits.