IBM 8265, Руководство по подготовке площадки, Страница: 59 / 164

Chapter 5. Planning for Twisted Pair Cable Connections
43
Balanced Mode Attenuation in dB/km
Notes:
1. The attenuation measurements from 9.6 kHz to 20 MHz were performed on 305 m
(or greater) reels.
2. The attenuation measurements from 20 MHz to 300 MHz were performed on 100
m reels using a North Hills 13410 or equivalent balun.
3. The attenuation in dB/km must be bounded by the following function:
for all frequencies (f) in MHz between 4 MHz and 20 MHz. k
o
is the attenuation in
dB/km at 4 MHz.
4. The attenuation in dB/km, measured on 100 m reels, must be bounded by the
following function:
for all frequencies (f) in MHz between 20 MHz and 300 MHz. k
o
is the attenuation
in dB/km at 62.5 MHz.
Frequency Type 1A Type 9A Type 6A Notes
9.6 kHz 3 dB 6 dB 6 dB 1
38.4 kHz 5 dB 7.4 dB 7.4 dB 1
4 MHz 22 dB 33 dB 33 dB 1
8 MHz 31.1 dB 46.7 dB 46.7 dB 1
10 MHz 34.8 dB 52.2 dB 52.2 dB 1
16 MHz 44 dB 66 dB 66 dB 1
20 MHz 49.2 dB 73.8 dB 73.8 dB 1
4–20 MHz see note 3 see note 3 see note 3 1, 3
25 MHz 61.7 dB 93.3 dB 93.3 dB 2
31.25 MHz 68.9 dB 104.3 dB 104.3 dB 2
62.5 MHz 97.5 dB 147.5 dB 147.5 dB 2
100 MHz 123.3 dB 186.6 dB 186.6 dB 2
20–300 MHz see note 4 see note 4 see note 4 2, 4
A f
( )
k
0
f
4
---
≤
A f
( )
k
0
f
62.5
------------
≤