Fluke DSX-600 - Db Rule; 67 Db Rule for ACR-F and PS ACR-F

DSX-600 CableAnalyzer
Technical Reference Handbook
92
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
3 and 4 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 4 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.
67 dB Rule for ACR-F and PS ACR-F
At frequencies where FEXT or PS FEXT is less than 67 dB, ACR-F or
PS ACR-F are not evaluated against a limit. See Tables 3 and 4 for
applicable limits.
70 dB Rule for ACR-F and PS ACR-F
These rules applies to all channel or permanent link test limits
where ACR-F is measured.