ANSI SCTE 133 pdf free download
ANSI SCTE 133 pdf free download.Downstream RF Interface for Cable Modem Termination System.
5 FUNCTIONAL ASSUMPTIONS
This section describes the characteristics of a cable television plant, assumed to be for the purpose of operating a data-over-cable system. It is not a description of EQAM or CMTS parameters. The data-over-cable system MUST be interoperable within the environment described in this section.
Whenever there is a reference in this section to frequency plans or compatibility with other services, or conflicts with any legal requirement for the area of operation, the latter shall take precedence. Any reference to NTSC analog signals in six MHz channels does not imply that such signals are physically present.
5.1 Broadband Access Network
A coaxial-based broadband access network is assumed. This may take the form of either an all-coax or hybrid fiber/coax (t-IFC) network, The generic term “cable network” is used here to cover all cases.
A cable network uses a shared-medium, “tree-and-branch” architecture, with analog transmission. The key functional characteristics assumed in this document are the following:
• Two-way transmission
• A maximum optical/electrical spacing between the DRFI-compliant device and the most distant CM of 100 miles in each direction, although typical maximum separation may be 10-15 miles
• A maximum differential optical/electrical spacing between the DRFI-compliant device and the closest and most distant modems of 100 miles in each direction, although this would typically be limited to 15 miles
At a propagation velocity in fiber of approximately 1.5 ns/ft, 100 miles of fiber in each direction results in a round- trip delay of approximately 1.6 ms. For further information, see IDOCSIS2], Appendix VIII.
5.2 Equipment Assumptions
5.2.1 Frequency Plan
In the downstream direction, the cable system is assumed to have a pass band with a lower edge between 50 and 54
MHz and an upper edge that is implementation-dependent hut is typically in the range of 300 to 870 MHz. Within
that pass band, NTSC analog television signals in six-MHz channels are assumed present on the Standard (STD).
HRC, or IRC frequency plans of ICEA-542-B1. as well as other narrowband and widehand digital signals.
5.2.2 Compatibility with Other Services
The CM and EQAM or CMTS MUST coexist with the other services on the cable network, for example:
I. They MUST be interoperable in the cable spectrum assigned for EQAM or CMTS-CM interoperation, while the balance of the cable spectrum is occupied by any combination of television and other signals, and
2. They MUST NOT cause harmful interference to any other services that are assigned to the cable network in spectrum outside of that allocated to the EQAM or CMTS. The latter is understood as:
• No measurable degradation (highest level of compatibility).
• No degradation below the perceptible level of impairments for all services (standard or medium level of compatibility), or
• No degradation below the minimal standards accepted by the industry (for example, FCC for analog video services) or other service provider (minimal level of compatibility).
ANSI SCTE 133 pdf download.
