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48
IBM 8265: Planning and Site Preparation Guide
Insertion Loss
Insertion loss is a measure of signal power loss due to the connecting hardware and is
derived from swept frequency voltage measurements on short lengths of Type 1A
twisted pair test leads before and after splicing-in the connector under test. The
insertion loss of any pair within a connector must not exceed the values listed in the
following table.
Table 30 shows the maximum insertion loss for the 150-ohm STP Data Connector
(applies to Prime and Self-Shorting paths):
Table 30. Maximum Insertion Loss for the 150-ohm STP Data Connector
Frequency
100 kHz
1 MHz
4 MHz
8 MHz
10 MHz
16 MHz
20 MHz
25 MHz
31.25 MHz
62.50 MHz
100 MHz
300 MHz
Data Grade Media (DGM)
Plenum (P), non-plenum (NP), riser (R), and non-plenum office (NPO): all indoor
cables except under-carpet require 65% (minimum) braid-over aluminum shielding.
The shielding percentage is calculated per MIL-C-915E. Aluminum-backed insulating
tape is wrapped around the two pairs. (Individual or S-shaped aluminum shielding
must be used around Type 1 and Type 2 DGM pairs and is optional for Type 6 and
Type 9 DGM pairs.) A tinned-copper braided shield envelopes these shielded pairs to
complete the DGM core. The aluminum must make contact with the braided shield
continuously along the entire cable length.
Under-carpet (UC) Shield
The under-carpet cable has a copper foil wrapped around each pair individually. The
seam of each copper foil must face the center of the cable.
dB
0.05
0.05
0.05
0.1
0.1
0.15
0.15
0.15
0.15
0.2
0.25
0.45
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