ANSI SCTE 196:2019 pdf free download – SFP-RF: Interface Specifications for an RF-Modulated Small Form Factor Pluggable Optical Module
The standardization and deployment of optical interfaces for headend equipment offer cost and power savings to MSOs. However, implementing optical interfaces in these devices presents significant technical challenges, since the lack of standardization may result in too many combinations of interfaces to support effectively in a headend device (power, wavelengths, cards, etc.). Because of this challenge, the following specification proposes a standard for the interfaces between a downstream laser transmitter module and its host. The module is based on the [SFF-8431], but the input will consist of RF-modulated signals that will be amplitude modulated onto an optical carrier. For the purpose of this specification, this module is referred to as SFP-RF. This SFP-RF optical transmitter module could be integrated into headend equipment, such as a Converged Cable Access Platform (CCAP), a Cable Modem Termination System (CMTS), an Edge QAM, or a forward optical transmitter shelf, reducing the need for devices dedicated to forward lasers. The SFP-RF optical transmitter module will function as a downstream laser for the output of cable edge devices. The primary difference between the SFP-RF optical transmitter module and the XFP-RF optical transmitter module is the size of the module and the link lengths supported.
This standard will focus on the communications, electrical, and mechanical interfaces for the SFP-RF optical transmitter module. Unless otherwise noted, requirements held within this standard apply both to the transmitter module and its host.
2.0 NORMATIVE REFERENCES
The following documents contain provisions, which, through reference in this text, constitute provisions of the standard. At the time of Subcommittee approval, the editions indicated were valid. All standards are subject to revision; and while parties to any agreement based on this standard 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 may not be compatible with the referenced version.
If the SFP-RF module is not sharing the I²C interface bus with other SFP-RF modules, the Mod_DeSel pin may be left low indefinitely. Otherwise, it shall be pulled high for at least 2 ms before another command is executed on the shared bus (presumably to a different SFP-RF module). Write operations may cause the SFP-RF module to not respond to further I²C signals or messages for up to 40 ms (t WR in Section 4.3, Table 27, and Section 4.5.7 of [XFP MSA]). The specification does not restrict this to EEPROM writes. This applies for writes from one to four bytes (the limit for a write is four bytes). The SFP-RF module may perform a clock stretch of up to 500 µs during read or write operations (T_clock_hold, [XFP MSA] Section 4.3, Table 27). This is distinct from unresponsiveness after a write operation (TWR ).