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AV Signal Performance and the Layer 1 Infrastructure

The presence of higher resolution 4K/UHD and HDR signals continues to proliferate in commercial AV environments as more content and compatible equipment come to market. The ability to manage the greater bit-depth, color gamut and bandwidth requirements (among other performance parameters) that come with these formats goes far deeper than one might imagine.

The quality of the infrastructure directly correlates to the health and quality of the signals moving through a facility. The better the cable and connectivity, the less the customer needs to worry about pixel drops, fuzzy images, and other audio-visual artifacts that lessen the impact. This is especially critical as facilities transition to IP networks that are, by nature, more sensitive to moving high-bandwidth 4K/UHD/HDR video traffic over long distances – and often, sharing that same infrastructure with data traffic from other applications.

The transition of AV components to IP also creates a need to think through the AV strategy earlier in the planning process. AV systems have become part of the actual network deployment, which requires stronger communication with both the room or building architects and the consultants who design the local area network. The robustness of Layer 1 infrastructure supporting IP traffic will play a substantial role in the quality of your AV signal performance.

Layer 1, “The Physical Layer” Defined

Layer 1 infrastructure has long been a topic of discussion on the edges of the AV industry, more suited to the low voltage contractors working behind the walls than the systems integrators deploying the AV hardware. Layer 1 of the open system interconnection (OSI) model represents the physical layer of computer networking that describes media (cable, connectors, and infrastructure) and signal transmission.  It also defines how electronic signals are sent and received. Importantly, this physical layer is not only the pathway for the next six layers of the OSI model, but the foundation for the overall network structure.

Important Choices

One of the more intense discussion points in this transitional period is the choice between shielded (foil or sheath protection) and unshielded cables and connectors. Many AV standards call for shielded products, which technically reduce electromagnetic interference (EMI, often caused by HVAC and lighting systems) and other noise through the infrastructure. 

While this improves data performance and maintains signal integrity, shielded cable and connectors require shielded jacks and couplers, and must be bonded and grounded. Without these precautions, signal performance is adversely affected through antenna effect, insertion loss and other artifacts. All of this will substantially raise costs and installation complexity. Shielded systems are also bulkier and more rigid than unshielded systems, which makes structural changes, headroom and scaling a challenge moving forward.

By contrast, unshielded cables will reduce costs and integration time while simplifying ongoing maintenance. Unshielded cables require less space in the supporting racks and conduits, allowing for better performance for Power over Ethernet (POE) devices. The ability to dissipate heat allows larger cable bundle sizes without compromising signal integrity through the infrastructure.

Insertion loss causes reflections that will adversely affect RF power into the connector, leading to pixel drops and other quality issues. The additional headroom of an unshielded Cat6A system will minimize insertion loss, and therefore minimize pixel drops or cancellation within the Layer 1 infrastructure. This means the elimination of banding, fuzzy or discolored video in the meeting space that comes with pixilation.

Adding modular, field-terminable plugs to connect devices to the infrastructure will add further benefits. For example, these enable horizontal cable runs direct to equipment, eliminating the need for jacks, surface-mounted boxes and/or patch cords. This will reduce installation times and upfront costs by up to 40 percent, while eliminating multiple points of failure in the network infrastructure. 

This only scratches the surface when it comes to planning a Layer 1 infrastructure for AV over IP deployments. However, these starting points will set you on the path to effectively optimize headroom and capacity, protect against packet and insertion loss, and make the best choices when it comes to the cable, connectors and electrical systems that ultimately drive the business and educational AV-based initiatives inside any modern facility.