In our industry, one thing we’ve always been able to count on is the need for signal transmission over longer and longer distances at ever-increasing quality. Over the years, both audio and video signals have been transmitted over a variety of physical media, in most cases meeting distance and quality goals. However, as resolutions improve and technological capabilities evolve, the goal line keeps moving on us.
For commercial integrators, a primary challenge is distributing AV signals with near-zero latency from a variety of sources to a myriad of displays in massive facilities—from corporate office buildings to university campuses. Transmission distance and quality are driving factors, which are further compounded by the need for cost effectiveness, ease of deployment, and scalability.
For these systems, packet-switching extenders convert AV signals to digital form and then break them into data packets that are sent over category media (CAT5e/CAT6/CAT7 or fiber-optic cabling) using a standardized communication protocol. Two of the more popular protocols are TCP/IP (AVoIP) and HDBaseT. The fundamental difference between the two is that IP systems can take advantage of standard Ethernet infrastructure, while HDBaseT systems can’t.
This has profound implications when it comes to transmission distance. HDBaseT systems are limited by their physical media. The range for CAT5e/CAT6 cable is 100 meters, which poses a big problem for these solutions in large networks. By utilizing existing Ethernet infrastructure, that limitation is eliminated for AVoIP systems, which can transmit full HD (even 4K) signals great distances with imperceptible latency by connecting network switches.
To illustrate this point, let’s take a university campus as an example. At the university, all AV sources are located in the mass communication building’s AV center. Each source is connected to a transmitter that encodes AV signals into IP data, which is fed to the network switch. Each display in the building is equipped with a receiver that decodes IP data back into AV signals. The network switch sends the IP data from the transmitters to these receivers, which send the decoded AV signals to the displays for playout.
The network switch in the mass communication building is connected to a switch in the engineering building via a fiber-optic link. That switch outputs the IP data from the mass communication building’s sources to another set of receivers connected to displays in the engineering building. And the engineering building’s switch is linked to another network switch in the student union, and so on, until the entire campus can view any source device located in the AV center.
With its advantages over HDBaseT, it’s not surprising that AVoIP continues to grow in popularity and deployment. As it does so, one component has become increasingly vital to the system: the network switch. Unlike traditional, more expensive AV matrix switchers, network switches aren’t pre-configured to a specific number of inputs and outputs (4x4, 8x8, 16x16 etc.). So, while AV switchers often fill up — leaving no room for the system to grow with new sources and displays without the purchase of another matrix — network switches don’t have the constraints of a fixed physical size because to the switch it is all simple IP data traffic (however there are bandwidth limitations to consider). To expand the distribution system, all that’s needed is a transmitter for each new source and receiver for each display.
Due to the central role network switches play, most AVoIP systems will require a higher-end solution. This isn’t the time to just grab the cheapest switch at the local discount store. It’s not going to handle the video traffic or have the features needed to properly manage the network. A managed Layer 2 / Layer 3 switch is almost always required.
Two of the more important features to look for when selecting a switch are support for virtual local area networks (VLANs) and IGMP snooping. VLANs allow the network to be segmented. Integrators can use them to isolate video traffic, preventing them from slowing down other parts of the network, and facilitating the sharing of sources among displays. IGMP is a mechanism for AV systems that utilize IP multicasting. It prevents the switch from sending multicast data to every port, degrading performance and chewing up network bandwidth.
For integrators, the goal line for signal extension will always be shifting. There’s already a push for the transmission of uncompressed AV signals with near-zero latency and streaming in 4K resolution is in high demand. But for today’s AV distribution needs, they’ve scored a touchdown with AVoIP systems utilizing managed network switches.