XRT72L50 Datasheet, PDF (414/471 Pages) Exar Corporation – SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER WITH HDLC CONTROLLER
REV. 1.2.1
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FA2 Framing Alignment octets. FA1 is assigned the value 0xF6, and FA2 is assigned the value of 0x28.
Figure 183, which presents an illustration of the E3, ITU-T G.832 Framing Format, indicates that these two
octets will occur at the beginning of each E3 frame, and that the FA2 octet will appear immediately after the
FA1 octet.
FIGURE 182. THE STATE MACHINE DIAGRAM FOR THE RECEIVE E3 FRAMER E3 FRAME ACQUISITION/MAINTENANCE
ALGORITHM
FA1, FA2
Octet
Search
FA1 and FA2 octets are
detected once
FA1, FA2
Octet
Verification
FA1 and FA2 octets are
not detected
LOF
Condition
FA1 and FA2 octets
are verified once
1 or 3 ms of operating
in the OOF condition
(user-selectable)
OOF
Condition
3 consecutive
Valid Frames
4 consecutive
In-valid Frames
In Frame
Frame Maintenance
Mode
401