INTELLIGENT BRANDS // Cabling
the difference in peak-to-peak magnitude
between the two signals on a twisted-pair
by performing a subtraction operation. In a
perfectly balanced cabling system, the induced
common mode signal would appear as two
equal voltages that are simply subtracted out
by the transceiver, thereby resulting in perfect
noise immunity.
In the real world, however, twisted-pair
cables are not perfectly balanced and their
limitations must be understood by application
developers and system specifiers alike. TIA
and ISO/IEC committees take extreme care
in specifying balance parameters such as TCL
(transverse conversion loss), TCTL (transverse
converse transfer loss) and ELTCTL (equal
level transverse converse transfer loss) in their
standards for higher grade (i.e. category 6 and
above) structured cabling. By examining the
performance limits for these parameters and
noting when they start to approach the noise
isolation tolerance required by various Ethernet
applications, it becomes clear that the practical
operating bandwidth defined by acceptable
levels of common mode noise immunity due
to balance is approximately 30 MHz. While
this provides more than sufficient noise
immunity for applications such as 100BASE-T
and 1000BASE-T, Shannon capacity modeling
demonstrates that this level provides no
headroom to the minimum 10GBASE-T noise
immunity requirements. Fortunately, the
use of shielding significantly improves noise
immunity, doubles the available Shannon
capacity, and substantially increases practical
operating bandwidths for future applications.
An effect of degraded twisted-pair signal balance
above 30 MHz is modal conversion, which
occurs when differential mode signals convert
to common mode signals and vice versa. The
conversion can adversely impact noise immunity
from the environment, as well as contribute to
crosstalk between pairs and balanced cables and
must be minimised whenever possible. Shielding
can decrease the potential for modal conversion
by limiting noise coupled onto the twisted-pair
from the environment.
(For the full white paper, please visit:
https://www.siemon.com/us/standards/
Screened_and_Shielded_Network_Cabling_
Guide.asp)
46
INTELLIGENTCIO
At a glance…
R&M acquires Silicon
Valley based REALM
Communications Group
Swiss Cabling specialist, R&M has announced the
acquisition of REALM Communications Group. Inc., a
North American fibre-optic specialist based in Milpitas,
California. Founded in 1987, REALM is a leader in
developing and supplying advanced fibre management
products for data centre, wireless antenna systems,
enterprise networks and the Silicon Valley’s OEMs.
“The acquisition of REALM offers R&M access to the
world’s most important network cabling market, allowing
us to serve customers on each continent with high-end
network solutions for the LAN, data centre and Public
Network markets,” says Michel Riva, CEO of R&M. “We
are very excited about the new growth opportunities with
this geographical expansion. REALM is not only providing
us with complementary technology but will also give us
access to high end-customers in the strongly growing
North American Data Centre market”.
REALM is well known for customer-specific, high-quality
cabling solutions in the local markets. In many ways, the
innovative and high-quality cabling solutions from REALM
and R&M are complimentary and offer an extended
solutions portfolio for the customers.
John Russell, Founder of REALM, said “Over the last 28
years, we have built excellent customer relationships
through our expertise in fibre-optic technology and our
ability to react swiftly to customer needs. We are thrilled
to become a part of R&M’s global organization. Together
we can accelerate our growth and take the company to
the next level.”
www.intelligentcio.com