VeEX VePAL TX300M, User Manual

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10.2.4 Pointer Tasks
Tap the Pointer Tasks icon to display the Pointer testing screens.
SDH/SONET Tools Menu
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10.2.4.1 Pointer Analysis
Pointers keep SONET signals synchronous by compensating for timing differences without having to use stuffing bits. Pointers are
allowed to move up or down every three frames however the actual rate should be slower. The Administrative Unit (AU) and the
Tributary Unit (TU) each has its own pointer and the unit has two tabs for displaying the values and measurements.
For STS pointers:
SS bits – displays bits 5 and 6 of the H1 byte to indicate SONET [10], SONET [00], Unknown [01] and [11] signal
type
Pointer value – displays the H1 and H2 values (addresses) indicating the offset in bytes between the pointer and
first byte of the STS-n
LOP (Loss of Pointer)
PJE and NJE
NDF or New Data Flag. NDF is enabled when all bits match "1001" (or "0001", "1101", "1011" and "1000") and is
disabled when all bits match "0110" (or "1110", "0010", "0100", "0111").
Difference and Sum
Analysis > P Pointer
TX300S_e-manual_D07-00-064P_RevA00