ANSI SCTE 257:2019 pdf download.Techniques for Accurate Measurement of Cable TV Network Downstream RF Signal Levels.
Proper cable network operation relies upon RF signal levels being within specification. RF signals are just about everywhere in modem cable systems: antenna sites, headends, hub sites, nodes, coax distribution networks, and subscriber drops. While ensuring that signal levels are what they’re supposed to be won’t fix or avoid every problem, correct signal levels are an important part of optimizing overall RF performance.
1.3. Benefits
Optimum cable network downstream performance requires that RF signal levels be measured and set correctly. RF signal levels affect nearly every part of a cable network’s operation: headend/hub site, optical fiber links, coax distribution, subscriber drops, and customer premises equipment (CPE). This Operational Practice discusses measurement of downstream signal levels, factors that can affect the accuracy of those measurements, and provides recommendations to ensure correct RF signal levels.
1.4. Intended Audience
This document is intended for cable system technical personnel such as installers, service and maintenance technicians, headend and hub site technicians, and others who have to measure signal levels as part of their daily jobs, or are interested in the measurement of signal levels.
1.5. Areas for Further Investigation or to be Added in Future Versions
Future versions of this Operational Practice (or a new and separate Operational Practice) could include information about the measurement of upstream RF signal levels.
2. Normative References
The following documents contain provisions, which, through reference in this text, constitute provisions of this document. At the time of Subcommittee approval, the editions indicated were valid. All documents are subject to revision; and while parties to any agreement based on this document are encouraged to investigate the possibility of applying the most recent editions of the documents listed below, they are reminded that newer editions of those documents might not be compatible with the referenced version.
2.1. SCTE References
• No normative references are applicable.
2.2. Standards from Other Organizations
• No norinative references are applicable.
2.3. Published Materials
• No normative references are applicable.
3. Informative References
The following documents might provide valuable intbrmation to the reader but are not required when complying with this document.
3.1. SCTE References
• SCTE Measurement Recommended Practices for Cable Systems, Fourth Edition.
3.2. Standards from Other Organizations
• [1] ISO 5725-1:1994 “Accuracy (trueness and precision) of measurement methods and results– Part 1: General principles and definitions”
3.3. Published Materials
• [2] Data-Over-Cable Service Interface Specifications Downstream RF Interface Specification CM-SP-DRFI-I15-160602 (http://www.cablelabs.cornlwp-content/uploads/specdocs/CM-SPDRFI-I15-160602.pdf).ANSI SCTE 257 pdf download.