XRT75VL00D_08 Datasheet, PDF (71/92 Pages) Exar Corporation – E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET

REV. 1.0.4
XRT75VL00D
E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER
Figure 46 presents an illustration of the bit format within the 16-bit word (consisting of the H1 and H2 bytes)
with the "D" bits designated.
FIGURE 46. AN ILLUSTRATION OF THE BIT-FORMAT WITHIN THE 16-BIT WORD (CONSISTING OF THE H1 AND H2
BYTES) WITH THE "D" BITS DESIGNATED
H1 Byte
H2 Byte
MSB
LSB
NNNNS S I D I D I D I D I D
10 Bit Pointer Expression
NOTE: At this time the "D" bits are inverted in order to denote that a "decrementing" pointer adjustment event is currently
occurring.
During the STS-1 frame that follows the "Negative Byte-Stuffing" Event
The "D" bits (within the pointer-word) will be set back to their normal value; and the contents of the H1 and H2
bytes will be decremented by one.
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