scope:

The present document defines the second generation of radio-frequency interface specifications for the second generation of high-speed Data-Over-Cable Systems. They were developed for the benefit of the cable industry, including contributions by operators and vendors from North America, Europe, and other regions.

The source material for this specification was provided by two sources. The first material was [33] for which the most recent version can be found at www.cablemodem.com. The second material source was the ITU-T Recommendation J.122 [47], for which the most recent version can be found at www.itu.int/ITU-T.

There are differences in the cable spectrum planning practices adopted for different networks in the world. Therefore two definitions for physical layer technology are included, which have equal priority and are not required to be interoperable. One technology definition is based on the downstream multi-programme television distribution that is deployed using 6 MHz channelling, and supports upstream transmission in the 5 MHz to 42 MHz region. The second technology definition is based on a multi-programme television distribution using 8 MHz channel spacing and supports upstream in the 5 MHz to 65 MHz region. Both options have equal status.

The first of these technologies is specified in clauses 4, 6 and 7, whereas the second definition is specified by replacing the content of those clauses with the content of annex F. Compliance with the present document requires compliance with only one of these implementations. It is not required that equipment built to one option shall inter-operate with equipment built to another. Annex F is maintained as a separate clause in the present document to provide for alignment of clause numbering and to maintain change control across documents from other standards organizations specifying similar technologies for other areas of the world.

These choices of physical-layer technologies allow operators some flexibility within any frequency planning, EMC and safety requirements that are mandated for their area of operation.

EXAMPLE: The 6 MHz downstream-based option defined by clauses 4, 6 and 7 might be deployable within an 8 MHz channel plan. It is the network operator's choice of which technology definition to deploy.

All optional physical-layer technologies are required to be backwards compatible with the earlier versions of those options defined in STCE 22-1 [2], ITU-T Recommendation J.112, annex B [3], and ITU-T Recommendation J.112, annex C [4].

Requirements for EMC and safety are outside the scope of the present document. EMC and safety standards for European applications are published by CENELEC. Compliance remains the operators' responsibility.

NOTE 1: Examples of such CENELEC product safety standards are EN 60950 [41] and EN 50083-1 [39].

NOTE 2: For CENELEC safety categories of interfaces, see EG 201 212 [34].

NOTE 3: Examples of such CENELEC product EMC standards are EN 50081-1 [37], EN 50082-1 [38] and EN 50083-2 [39].