Filter
Top Products
CHAPTER 2:
INSTALLATION REQUIREMENTS/SPECIFICATIONS
2-2
SEH USER’S GUIDE
2.1.2 10BASE-T UTP and STP Cable Specifications
The devices and 10BASE-T Twisted Pair Segments connected to the SEH
10BASE-T Twisted Pair Network Ports and EPIM-T module must meet
the IEEE 802.3 10BASE-T specifications shown below.
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 maximum
link length. With high quality, low attenuation cable, link lengths of up to
200 meters are achievable. Cable delay limits maximum link length to
200 meters, regardless of cable type.
Insertion Loss
The maximum insertion loss allowed for a 10BASE-T link is 11.5 dB at
all frequencies between 5 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, can also be used.
The impedance of IBM Type 1 cable is typically 150 ohms. This increases
the signal reflection caused by the cable, but because the cable is shielded,
this 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.
SEH Book Page 2 Tuesday, March 19, 1996 4:12 PM