October/November/December 2019 I 7
AV SIGNALS AND SERVICES THAT
USE NETWORK INFRASTRUCTURE
Voice over Internet Protocol (VoIP)
VoIP is the transport of voice communications over the
internet. It can provide substantial savings over plain
old telephone service (POTS) because it integrates into
existing data networks. Any computer on the network can
double as a telephone. There are no service charges based
on time or distance, and services like call waiting, caller
ID, call forwarding, and voicemail are included at no
extra cost.
Video and Audio
Video and associated audio content can be transported
point-to-point over twisted-pair uncompressed (HDBaseT)
or it can be streamed compressed and packetized over
Ethernet data networks and the internet (AV over IP).
HDBaseT offers no-latency transmission of uncompressed
ultra-high definition 4K video. Audio and control signals
over shielded twisted-pair cable reaching up to 328 feet
(100 meters) makes it a reliable plug-and-play AV content
extension method in point-to-point applications. AV over
IP is rapidly gaining favor for on-demand and real-time
delivery of AV content to numerous and widely dispersed
recipients over long distances. The cost effectiveness
of transporting AV content over existing Ethernet infrastructure,
the inherent scalability of Ethernet networks,
and advances in visually lossless and low latency video
compression algorithms are driving the move to AV
over IP.
Building Management Systems (BMS)
These systems are comprised of devices and software that
communicate over twisted-pair cable networks to control
building systems, such as HVAC, lighting, power, fire,
and security. AV and BMS are converging because AV
control processors can support BMS protocols via software
modules and device drivers. Not only can an AV
control processor preserve lamp life by shutting down
projectors after hours, but it can also reduce HVAC costs
by drawing window shades during the heat of the day,
open shades to harvest natural light, and adjust room
temperature based on occupancy. Blending BMS and AV
requires expertise with building automation protocols,
such as building automation and control networking
protocol (BACnet), Konnex (KNX), and digital addressable
lighting interface (DALI):
• BACnet to communicate between building
automation end devices and building
control systems
• KNX for intelligently networking home
and building systems
• DALI for control of lighting via two-way
communication bus
BICSI Registered Communications Distribution
Designer (RCDD) Certified Specialists
Bring Their Expertise to the AV Team
By joining AV design and installation firms or through
ICT firms taking a lead role in AV design and installation,
RCDD certified personnel become integral members
of an AV team. Therefore, it is important for them to
understand the guidelines for distributing AV over
the network.
CONSIDERATIONS FOR
MANAGING AV SIGNALS
Connections
There are four digital AV interfaces in widespread use:
digital visual interface (DVI), high definition multimedia
interface (HDMI), DisplayPort, and USB-C. DVI
carries video only at resolutions up to 2560 x 1600.
With higher resolutions becoming the norm, it is
understandable that DVI has been supplanted by
HDMI and other connections. The latest version of
HDMI transports up to 10K video, multichannel audio,