Chapter 3: Installation Requirements and Specifications
3.1.2UTP Cable Specifications
The device at the other end of the twisted pair segment must meet IEEE 802.3u 100BASE-T specifications. When connecting a 100BASE-TX Twisted Pair Segment to the SEHI twisted pair network ports and the EPIM-100TX module, the network must meet the following requirements:
Length
The IEEE 802.3u 100BASE-T standard requires that 100BASE-TX devices be able to transmit over a 100 meter (328 foot) link using Category 5 UTP wire. The cable used must meet the Horizontal requirements and 90-meter length limitations. Patch cable should be used on each end of the Horizontal wire to make connections to punch down blocks, panels, and other connecting devices. The combined lengths of the patch cords must not exceed 10 meters so the total segment length does not exceed 100 meters (328 feet).
Category 5 cables are marked on the cable jacket as Cat 5, Category 5, Level 5, Level V, or an equivalent.
Impedance
UTP cables typically have an impedance of between 85 to 110 ohms.
Jitter
Intersymbol interference and reflections cause jitter in the bit cell timing, resulting in data errors. A 100BASE-TX link must not generate more than
1.4ns of jitter. If the cable meets the impedance requirements for a 100BASE-TX link, jitter should not be a concern.
Crosstalk
Crosstalk is caused by signal coupling between the different cable pairs contained within a multi-pair cable bundle. 100BASE-TX transceivers are designed so that the user does not need to be concerned about cable crosstalk, provided the cable meets all other requirements.
Noise
Noise is caused by either crosstalk or externally induced impulses. Impulse noise may cause data errors if the impulses occur at very specific times during data transmission. Generally, the user need not be concerned about noise. If noise-related data errors are suspected, it may be necessary to either reroute the cable or eliminate the source of the impulse noise.
