ANSI SCTE 55-1:2019 pdf download.Digital Broadband Delivery System: Out of Band Transport-Part 1: Mode A.
5. OUT-OF-BAND SYSTEM SPECIFICATIONS
This document specifies the Physical Layer and the Data Link Layer (including the MAC Layer) of the OutOf-Band cable system transport. Section 5 describes the Physical Layer protocol. Section 6 describes the Data Link Layer protocol.
The MAC Layer specification refers to the DOCSIS [3]. However, not all DOCSIS specifications for the MAC Layer are required. The minimum set is specified. Future enhancements toward full DOCS1S compliance are expected based on customers’ input.
This specification assumes that the reader has some:
1. fundamental understanding of the conventional cable frequency plan. and
2. familiarity with the Ethernet specification and the Reed-Solomon Coding of Error Correction Schemes.
Also use of the references denoted in Section 3 are highly recommended for a full understanding of this specification.
6. PHYSICAL LAYER SPECIFICATION C
This section describes the physical layer of the Out-Of-Band downstream and upstream channels.
6.1. PHYSICAL LAYER FOR OOB TRANSMISSION
The aggregate information rate of the Out-Of-Band (OOB) channel is 2.048 Mbps. Up to 1.544 Mbps may be utilized for access control and other control information as well as application data, application program downloads, program guides. etc. The OOB data channel provides continuous communication from a headend to the Digital Terminals. The Digital Terminal typically remains powered-up even when it is in the off’ state. The 0013 channel remains active independent of the tuned video channel, whether the received TV channel is analog or digital. and whether the Digital Terminal box is turned “on” or “off’. Thus, whenever the Digital Terminal connected to the coaxial cable and AC power, the OOB channel is active for downstream communication.
6.1.1. OOB TRANSMISSION FORMAT
The tbllowing table summarizes the physical attributes ot the OOB channel.
6.1.2.3. OOB INTERI4EAVER
Interleaving the coded R-S symbols before transmission and dc-interleaving after the reception may cause multiple burst errors during transmission to be spread out in time. Thus, the receiver has to handle them as if they were random errors. Separating the R-S symbols in time enables the random-error-correcting R-S code to be useful in a bursty-noisy environment. Using a convolutional interleaver with a depth of I = 8 symbols, the R-S T= 1 (96,94) decoder can correct an error burst of 8 symbols, which corresponds to a burst noise protection of 32 usec.
Interleaving is synchronized to the R-S blocks and hence to MPEG-TS packets. MPEG-TS Sync bytes always pass through commutator branch 1 of the interleaver and hence are not delayed through the interleaver. The convolutional interleave algorithm delays various blocks of bytes in a systematic way, as illustrated in Figure 5.ANSI SCTE 55-1 pdf download