ANSI SCTE 252-2018 pdf free download – Attenuation of Common Mode Filters.
Interference from devices or the environment can travel along the outer conductor of a coaxial cable as a common mode current. This current creates a common mode disturbance that can impact the upstream integrity of a cable plant.
SCTE 249 is the test method used by the cable industry for measuring the amplitude and frequency of these disturbances. Common mode filters (or attenuators) can be used to attenuate the amplitude of these disturbances. This test method creates an industry accepted standard for testing the attenuation of these common mode filters.
1.2. Scope All common mode filters or attenuators up to 230 MHz in frequency (limited by the upper frequency cutoff of commercially available coupling-decoupling networks) can be characterized using this test method.
1.3. Benefits This test method provides an industry accepted standard for testing the effectiveness of common mode filters.
1.4. Intended Audience Cable industry.
1.5. Areas for Further Investigation or to be Added in Future Versions Expand scope and testing methodology to include devices that provide active filtering or cancellation of common mode disturbance.
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
• SCTE 249 Test Method Common Mode Disturbance
2.2. Standards from Other Organizations
• CISPR 22:2008 (EN55022:2010) Information technology equipment – Radio disturbance characteristics – Limits and methods of measurement
• CISPR 16-1-1 Part 1-1: Radio disturbance and immunity measuring apparatus – Measuring apparatus
• IEC 61000-4-6 Electromagnetic compatibility (EMC) – Part 4-6: Testing and measurement techniques – Immunity to conducted disturbances, induced by radio-frequency fields
2.3. Published Materials
• No normative references are applicable.
3. Informative References
The following documents might provide valuable information to the reader but are not required when complying with this document.
• No informative references
3.1. SCTE References
• No informative references are applicable.
3.2. Standards from Other Organizations
• No informative references are applicable.
3.3. Published Materials
• No informative references are applicable.
6. Required Information This document is a general test method. It is designed for use in many different situations. As such, it is written to be only as specific as is necessary. The missing specific details necessary to perform this test are referred to as “Required Information.” The “Required Information” is to be provided by the customer.
The information required to perform this test method includes, but is not limited to:
• definition of a Device Under Test (DUT)
• the required number of DUTs
• frequency range(s) across which the test is to be performed
• the environmental conditions (temperature, humidity, etc.) at which the tests shall be performed
• the acceptance criterion
7. Discussion
CM filters may exist in the form of discrete chokes, or integrated into cables or other devices. This test method provides a way to measure the effectiveness of these filters by measuring the attenuation over frequency of these filters.ANSI SCTE 252 pdf download