XRT75L04D Datasheet, PDF (60/98 Pages) Exar Corporation – FOUR CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER

XRT75L04D
áç
FOUR CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER REV. 1.0.1
FIGURE 32. A SIMPLE ILLUSTRATION OF THE STS-1 FRAME STRUCTURE WITH THE TOH AND THE ENVELOPE
CAPACITY BYTES DESIGNATED
3 Bytes
90 Bytes
87 Bytes
TOH
Envelope Capacity
9 Row
Since the TOH bytes occupy the first three byte columns of each STS-1 frame, and since each STS-1 frame
consists of nine (9) rows, then we can state that the TOH (within each STS-1 frame) consists of 3 byte columns
x 9 rows = 27 bytes. The byte format of the TOH is presented below in Figure 33.
56