Instruction Manual

4
Designing a Coaxial Cable System to an Attenuation Limit
Attenuation on RIO network appears a signal passes through taps, splitters, splices, cables, connections and feed-
through terminators. The attenuation between the head processor (or the last optical fiber repeater, if an optical link is
used) and any drop adapter must not exceed 35 dB at 1.544 MHz. If the cable design exceeds the maximum attenuation
limit, transmission error may occur on the network.
Cable attenuation: 97-5750-000 RG6 cable has 1.18dB/100m (0.36dB/100ft) attenuation at 1.544MHz.
97-5951-000 RG11 cable has 0.56dB/100m (0.17dB/100ft) attenuation at 1.544MHz.
Tap attenuation: All RIO taps have a 14dB drop loss and a 0.8dB insertion loss.
Maximum system attenuation at 1.544 MHz can be calculated as follows:
dB loss = TCA + DCA + TDA + (Number of splitters x 6) + (Number of taps x 0.8)
Where:
• TCA = the trunk cable attenuation from the head to the end of the trunk.
• DCA = the drop cable attenuation, generally at the last drop.
• TDA = 14 dB, the tap drop attenuation.
Note: On a network using dual or redundant trunk cables, calculate attenuation on each section separately. Each trunk
on a dual or redundant RIO network can handle attenuation up to 35 dB.
Note: Use (Number of Splitters x 3.5) if MA-0331-000 is to be installed.
Specific use of Optical fiber repeaters (490NRP95400)
490NRP954 Optical Fiber Repeaters can be introduced in an RIO cable topology to allow you the transition from coaxial
to fiber cable then back again to coax at one or more of the remote drops on any RIO network.
RIO Optical fiber Topologies
RIO network topologies, when using optical fiber
repeater, are precisely defined (point-to-point, bus,
tree or self-healing ring) and cannot be derogated
from. Illegal topology may result into RIO Network
dysfunction.
A maximum of five NRP repeaters can be used in a
bus or ring topology.
The maximum distance between two repeaters is
limited by the attenuation and the jitter of the optical
fiber cable. This must be calculated separately from
coaxial cable attenuation. The maximum length of
optical fiber in a self-healing ring is 10km (32809 ft).
Note: On CRP side, the coaxial cable coming out of
a tap from the trunk cable, running into a NRP optical
fiber repeater is a drop cable. On CRA side, the
coaxial cable coming out of a NRP, running into a tap
to service CRA drops is a trunk cable.
Note: For more information, see RIO Cable System
planning & installation guide (890USE10100) or
Optical Fiber Repeaters User’s Guide (GM-FIBR-
OPT).