User guide
27
Link cable interference protection
While the Category rating (e.g. CAT 5e, CAT 6a, etc.)
determines the electrical performance of a cable, another
vital part of the overall cable specification is its protection
from interference. As cabling distances and data rates
increase, so too does the susceptibility to interference,
from both external and internal sources.
Proximity to other electromagnetic sources are the main
external threat and these can be subdued using overall
screening that surrounds all four of the cable pairs.
However, interference is also possible from neighbouring
twisted pairs within the same cable and this can be
just as hazardous to data integrity. Such crosstalk is
countered by shielding each cable pair separately.
Within each Category rating, you can specify different
combinations of external screening and internal shielding
to suit the environment into which the link is being
placed. Please see the section Tips for achieving good
quality links for suggested combinations.
Interference protection codes
Interference protection is now classified in the following
manner:
U/UTP
Appendix D
Name Overall Screening Pair Shielding
U/UTP û û
F/UTP
ü
û
U/FTP û
ü
S/FTP
ü
ü
or S/STP
or PiMF
U/UTP
F/UTP
U/FTP
S/FTP
S/STP
PiMF
Pair shielding
Overall screening
Outer sheath
General cable anatomy
where
U = unshielded
F = foil shielding
S = braided shielding
PiMF = Pairs in Metal Foil
Overall
screening
Pair
shielding
Twisted
Pair