
Operating the TSG-3800
Selecting the Input Reference Signal
86
TSG-3800 User’s Guide
12778474-002-2 Revision F – March 2004
Priority
SQL
Position
The primary selection criteria is the input signal priority level described in
Priority
Level
, on page 83. The system selects the highest priority level (1-4). The selection
order proceeds from highest priority to lowest priority. When two or more input
signals have identical priority levels and the levels are the highest priority setting,
the system uses the signal with the highest Synchronous Quality Level (SQL). SQL
is the hierarchy the TSG-3800 assigns to the SSMs (provisioned or received). If the
SQL is the same for all input signals, then the Input module in the lowest slot
number (increases from left to right in the shelf) is used. If a three-input Input
module is installed, then the lowest valid input channel is used.
If no input is error-free, the input with the least severe errors (but not failed) is
selected. If no input signal is valid, then no input will be selected and the TSG-3800
switches to Holdover mode operation.
Setting the Input Reference Selection Mode
, on page 327, describes how to set the
priority mode of operation. The syntax for setting the priority for an input is
described in
Input Command
, on page 350.
SSM Mode
In SSM mode, the input SQL is the first criteria when selecting a reference.The
selection order is as follows:
SQL
Priority
Position
The SQL comes from the SSM in the input signal or from the provisioned value. If
the Clock SQL is higher than the input SQL, then the input will be passed over when
selecting the reference. Otherwise, the SQL is used only to distinguish between
references with the same priority.
Setting the Input Reference Selection Mode
, on page 327, describes how to set the
priority mode of operation. The syntax for setting the SQL for an input is described
in
SSMs and Input Modules
, on page 84.
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