XRT75R03D_06 Datasheet, PDF (113/135 Pages) Exar Corporation – EXAR DATA SHEET FORMAT TEMPLATES

XRT75R03D
REV. 1.0.4
THREE CHANNEL E3/DS3/STS-1 LINE
b. The "Transmitting" Network Element will notify the remote terminal of this "negative-stuff" event by
inverting certain bits within the "pointer word" (within the H1 and H2 bytes) that are referred to as "D"
bits.
Figure 47 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 47. 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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