Clear-Com Communication Systems
Encore System Installation Instruction Manual
1-6
CROSSTALK CONSIDERATIONS IN A MULTI-CHAN-
NEL SYSTEM
In a multi-channel system where multiple channels are run from a Main
Station to a Remote Station as in the following diagram, crosstalk can
be an issue. This is because the channels will share a common
ground at both ends of the cable run.
Figure 1-6: Party Line Multi-Channel Configuration
When multiple channels are fed to Remote Stations, the amount of
crosstalk between channels is proportional to the DC resistance of the
ground return path back to the channel terminations. To minimize this
crosstalk between channels when running more than one channel in a
multi-pair cable, keep the DC resistance of the ground return as low as
possible. Ideally, this should be less than 2 Ohms. This can be
achieved as follows:
• Keep cable runs under 500 feet. If a longer cable run is
unavoidable and approaches 1000 feet or more, make sure
the appropriate lone line option switches or jumpers are set in
the stations. Refer to the individual station manuals for
further information.
• Use a cable whose common shield has a low DC resistance.
• Connect unused cable wires of a multi-pair cable to the Pin 1
shield.
Note: All multi-pair cables must have individually shielded pairs.
Clear-Com recommends the Belden 1800 Series of multi-pair cables.
They offer a common shield with a low DC resistance in addition to
individual shields on each pair.
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