User`s guide

CHAPTER 2: INSTALLATION REQUIREMENTS/SPECIFICATIONS
2-2 SEHI USER’S GUIDE
2.1.2 UTP and STP Cable Specifications
The device at the other end of the twisted pair segment must meet IEEE
802.3 10BASE-T specifications. When connecting a 10BASE-T Twisted
Pair Segment to the SEHI 10BASE-T Twisted Pair Network Ports and
EPIM-T module, the network must meet the following requirements:
Length
The IEEE 802.3 10BASE-T standard requires that 10BASE-T devices
transmit over a 100 meter (328 foot) link using 22-24 AWG unshielded
twisted pair wire. However, cable quality largely determines the
maximum link length. With high quality, low attenuation cable, link
lengths of up to 200 meters are achievable. Cable delay limits the
maximum link length to 200 meters, regardless of the cable type.
Insertion Loss
The maximum insertion loss allowed for a 10BASE-T link is 11.5 dB at
all frequencies between 5.0 and 10 MHz. This includes the attenuation of
the cables, connectors, patch panels, and reflection losses due to
impedance mismatches in the link segment.
Impedance
Cabletron Systems 10BASE-T Twisted Pair products work on twisted pair
cable with 75 to 165 ohms impedance. Unshielded twisted pair cables
typically have an impedance of between 85 to 110 ohms.
Shielded twisted pair cables, such as IBM
Type 1 cable, are also used. The
impedance of IBM Type 1 cable is typically 150 ohms. Higher impedance
IBM Type 1 cable increases signal reflection, but because the cable is
shielded, signal reflection has little effect on the received signal’s quality
due to the lack of crosstalk between the shielded cable pairs.
Jitter
Intersymbol interference and reflections cause jitter in the bit cell timing,
resulting in data errors. A 10BASE-T link must not generate more than
5.0 ns of jitter. If the cable meets the impedance requirements for a
10BASE-T link, jitter should not be a concern.