REQUIREMENTS/SPECIFICATIONS
Page 2-3
As a general rule, links up to 130 meters in length for unshielded
twisted pair and 200 meters in length for shielded twisted pair
are achievable. For each connector or patch panel in the link,
subtract 12 meters from the 150 meter limit. This will allow for
links of up to 126 meters using standard 24 AWG UTP wire and
two patch panels within the link. Higher quality low attenuation
cables may be required when using links of greater than 126
meters. Due to cable delay, the maximum link length is always
limited 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 - 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. You should
remember that the impedance of IBM Type 1 cable is typically
150 ohms. This increases the signal reflection caused by the
cable, but since 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. Cabletron Systems’
10BASE-T Twisted Pair products will work on twisted pair cable
with 75 to 165 ohms impedance.
•
Jitter - Intersymbol interference and reflections can cause jitter
in the bit cell timing, resulting in data errors. A 10BASE-T link
must not generate more than 5.0 nsec. of jitter. If your cable
meets the impedance requirements for a 10BASE-T link, jitter
should not be a concern.
•
Delay - The maximum propagation delay of a 10BASE-T link
segment must not exceed 1000 nsec. This 1000 nsec. maximum
delay limits the maximum link segment length to no greater than
200 meters.
•
Crosstalk - Crosstalk is caused by signal coupling between the
different cable pairs contained within a multi-pair cable bundle.
10BASE-T transceivers are designed so that the user does not
need to be concerned about cable crosstalk, provided the cable
meets all other requirements.
Summary of Contents for MRX
Page 11: ...INTRODUCTION Page 1 6...
