Provisioning Output Frequencies - Symmetricom SSU-2000e User Manual

Chapter 8 Output Module Reference Data
RS-422 Output Module
The user can provision the output port frequency from 8 kHz to 4096 kHz in 8 kHz
increments. The frequency selected for port 1 (balanced) is also present on port 11
(single-ended); the frequency selected for port 2 determines the frequency for port
12, and so on.
The RS-422 Output module can be used individually or configured for operation as
redundant pairs in the shelf. When redundant modules are installed and the
frequency is changed on one module, the redundant module turns its output off,
changes to the new frequency locking in phase with it, and then turns its output
back on.

Provisioning Output Frequencies

You use software commands to set the frequency of each port on the RS-422
Output module. Commands are available in both ICS and TL-1 modes. To provision
the output frequency using ICS or TL1 commands, see the SSU-2000e Technical
Reference.
Note: You can set frequencies on port 1 through port 10. Port 11
follows the frequency setting of port 1. Port 12 follows the frequency
setting of port 2, etc. Ports 1 and 11, 2 and 12, ... 10 and 20 have the
same frequency setting.
Output Squelching
The RS-422 Output module allows you to selectively turn off (squelch) the outputs
during periods of degraded performance. To use this feature, the Communications
module must have Revision D or later firmware.
This feature allows you to turn off any of 20 output ports on redundant or
non-redundant modules. The SSU-2000e uses the system Priority Quality Level
(PQL) to determine when the system is operating within specified limits; if the
outputs become degraded, the system automatically turns off the affected ports.
To enable the squelching feature, you must provision a "threshold" PQL value using
the OUTPUT command (for ICS mode) or the SET-PRMTR-CLKOUT command (for
TL1 mode). The syntax for each command is shown below. A threshold PQL value
of zero disables the squelch function. Threshold PQL values above zero enable the
squelch function; when the system PQL is greater than the threshold PQL, the
output is squelched.
For example, you can provision output ports 1 through 5 for a threshold PQL of 3
and you can disable squelching for ports 6 through 20 (PQL is set to 0). In this
example, if the system PQL is 1, 2, or 3, ports 1 through 20 generate outputs. If the
system PQL changes to 4 or higher, outputs on ports 1 through 5 are squelched
(disabled) and ports 6 through 20 continue to generate outputs. The response from
the Output Status command appears as shown in the following example.
216 SSU-2000e User's Guide 12713140-002-2 Revision E – October 2006