Executive Summary
The latest versions of Data-Over-Cable Service Interface Specifications (DOCSIS®) outline many upstream performance parameters which operators may make use of to find, localize, and remove (troubleshoot) upstream radio frequency (RF) problems.
Due to the funneling behavior of coax plant, upstream issues such as noise and ingress can affect large numbers of customers in highly service impacting ways.
Operators have a broad choice of frequency splits to implement, which impacts how upstream spectrum is treated, and therefore is an important consideration.
Amplifier designs, network actives and passives, and differences in home wiring designs all have an impact on how operators need to maintain the coax plant for reliable upstream RF performance.
While operator access to various measurements and tests are not uniform, the capabilities are reaching deeper into networks, allowing operators to take greater advantage of network capabilities that do not require external test devices. This is great news for operators, enabling them to reduce their maintenance costs while improving network and service reliability.
As more RF signals travel upstream, let’s not get caught without a paddle!
Scope
The material contained within this document applies directly to DOCSIS 3.0 and higher compliant customer premises equipment (CPE) which have implemented full band capture (FBC) functionality. It does not include non-DOCSIS connected devices such as Multimedia over Coax Alliance (MoCA) or Wi-Fi®, which may or may not have similar capabilities. This document, which emphasizes upstream spectrum issues, complements the material in SCTE 280 [1], “Understanding and Troubleshooting Cable RF Spectrum,” which focuses primarily on downstream spectrum issues. Given that many concepts and much material applies to both downstream and upstream spectrum, there is significant content in this document that discusses downstream issues while the emphasis is on upstream spectrum issues.
Benefits
This Industry Reference provides a valuable tool for cable field operations and engineers to better interpret cable RF spectrum performance. The document also provides operational perspectives about detecting, interpreting, and repairing problems that are often unique to coaxial cable networks. The intent of this document is to produce consistent interpretation and treatment of problems, improve repair times, and reduce rework caused by misinterpretation.
Intended Audience
The intended audience of this document is primarily field-facing technicians; the document is useful for analysis and repair teams. It also may be useful for software designers and systems engineers.