![Symmetricom TimeProvider 2300 User Manual Download Page 199](http://html.mh-extra.com/html/symmetricom/timeprovider-2300/timeprovider-2300_user-manual_1419620199.webp)
098-00564-000 Revision A3 – July, 2013
TimeProvider 2300/2700 User’s Guide
199
Chapter 4 Provisioning
Provisioning the Input Reference
Auto Switch Mode
In Auto-switch mode, the currently selected reference will not switch to another valid
input port until it is disqualified or the reference is manually disabled.
Reference Selection Criteria
Use either the Priority settings or the PQL settings (input PQL values or
user-configured PQL) for each qualified input port to determine which input port to
use as the reference.
Priority
The TP 2300/2700 uses the Priority settings for each qualified input port to
determine which input port to use as the reference. Priority values can be from 1 to
10, where 1 is the highest priority level. If two input ports are set to the same priority
value and both are qualified, the predefined preference is used (see
).
Predefined preference has the same value as the default priority value, but cannot
be changed. Reference selection among inputs with the same priority is
non-revertive.
PQL
Different inputs have different ways of specifying their quality levels. All of them are
mapped to a uniform internal quality ranking called priority quality level (PQL). After
all input quality levels are converted to PQL, the PQL will be used as one of the
reference selection criteria. PQL can be determined from information in the
reference signal or can be configured by the user.
PQL for Inputs
The PQL can be used for reference selection. Signals that can be assigned PQL
include all frequency-only signals (SyncE, E1 and T1) and all time signals (GNSS,
PTP, and TOD/PPS).
SyncE, E1 and T1 synchronization signal quality levels are characterized by SSM.
PTP synchronization signal quality level is characterized by clockClass. Input
signals like GNSS do not carry a synchronization signal quality indicator; they are
assigned an input PQL value appropriate to their known quality level. For example,
GNSS and cesium clocks are usually given a PQL value of 1 (the highest quality).
See
Configured PQL
The TP 2300/2700 allows the user to apply a provisioned PQL value rather than the
received PQL value for each input for reference selection
.
By inputting a "configured
PQL value", the user implicitly chooses the quality of an input signal relative to
others in the input conversion table.