Technical Guide |
Digital & Analog Partyline Intercom Cabling Comparison
Nov2018
Page 5
Conclusions
Cable Types
Analog and digital partyline intercom systems place
different demands on the cables used and whilst some
cables are very good for both systems, some that are fine
for one are not good for the other.
•
Analog systems require good shielding and little
attention needs to be paid to attenuation at
higher signal frequencies.
•
Digital systems require particular attention be
paid to attenuation at frequencies into the MHz
range.
Due to the combination of their low DC resistance and low
attenuation at 25MHz data rates, Clear-Com recommends
the use of:
•
Belden 9207 cable for fixed digital partyline
installations.
•
Belden 9463F cable for portable or temporary
digital partyline installations.
See Belden’s website at:
www.belden.com
for
more details.
It is worthy of note that star quad cables have very high
attenuation at 25MHz making them particularly poorly
suited to digital partyline applications.
Limit Conditions
The nature of analog and digital systems dictates that
their failure mechanisms are different when cable
requirements aren’t met.
Figure 9 and Figure 10 below give a comparison of what
a user can expect from analog and digital partyline
systems when approaching the limits of their cable’s
capabilities.
Calculator
The information included in this technical guide can be
used to calculate the maximum acceptable cable length
for any Clear-Com digital partyline system.
Alternatively, a user or prospective user can use the
calculator spreadsheet available at the link below to
determine whether a particular cabling installation meets
the requirements of Clear-Com digital partyline.
Digital Partyline Calculator
Cable Length
Number of Units
Excellent
Performance
Good
Performance
Satisfactory
Performance
Degraded
Performance
Does Not
Operate
Figure 9 Analog Partyline Performance with
increasing Cable Length and Number of Units
Cable Length
Number of Units
Excellent
Performance
Degraded
Performance
Does Not
Operate
Figure 10 Digital Partyline Performance with
Increasing Cable Length and Number of Units
