IBM 8265, Руководство по подготовке площадки

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Chapter 5. Planning for Twisted Pair Cable Connections
47
STP Connector Characteristics
The near-end crosstalk and insertion loss specifications below are intended to extend
the specifications in ANSI/IEEE 802.5 when the connectors are to be used with a
cable that meets the Type 1A, 2A, and 6A specifications described above.
Near-End Crosstalk (NEXT)
Near-end crosstalk is a measure of signal coupling from one circuit to another within a
connector, and is derived from swept frequency voltage measurements on short
lengths of Type 1A STP test leads terminating at the connector under test. A
balanced input signal is applied to a disturbed pair of the connector while the induced
signal on the disturbed pair is measured at the near end of the test leads.
The near-end crosstalk of any pair must not exceed the values listed in the following
table.
Note:
(f) in MHz
Table 29. Near-End Crosstalk for the 150-ohm STP Data Connector
Frequency dB
100 kHz
−
65
1 MHz
−
65
4 MHz
−
65
8 MHz
−
65
10 MHz
−
65
16 MHz
−
62.4
20 MHz
−
60.5
25 MHz
−
58.5
31.25 MHz
−
56.6
62.50 MHz
−
50.6
100 MHz
−
46.5
300 MHz
−
36.9
11.89 to 300 MHz see #
#NEXT(f) NEXT(16)
≤
20
f
16
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