Output Squelching - Symmetricom SSU-2000e User Manual

Chapter 8 Output Module Reference Data
2048 kHz Output Module
The 20 sets of 2048 kHz signal pairs TTIP and TRING represent a transformer-
coupled symmetrical pair. Each output can be turned on/off independently of other
channels; relays on each output allow for disconnecting the driver output from the
output pins. Each output signal is monitored for a failed output on an independent
basis. An output signal is designated failed when the level falls below 0.75 volts
base to peak.
In non-redundant configuration a failed output will not be turned off, as some
equipment may tolerate a wide range of level and still be operating. In redundant
operation a failed output will be turned off in one module at a time to try and isolate
the source of the problem. The outputs meet the criteria set forth in ITU-T G.703 for
signal type, amplitude, and waveshape.

Output Squelching

A new feature, available with Revision C of the firmware for the 2048 kHz 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, then 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, then ports 1 through 20 generate 2048 kHz
outputs. If the system PQL changes to 4 or higher, then outputs on ports 1 through 5
are squelched (disabled) and ports 6 through 20 continue to generate 2048 kHz
outputs. The response from the Output Status command appears as shown below:
SSU+>out 2a10
2002-12-03T15:30:14 ID: SSU2000 Name:SSU
Module Name: Output 2048 kHz
OUT STATUS Clk Clk Stat
Loc# Type Sta Sel
---- ---- --- ---
2A10 2048 Ok A
OUTPUT SETUP
Loc# Type ZS MinClk Bypass
---- ---- ---- ------ ------
210 SSU-2000e User's Guide
A B C D Redt Pql
-------- ---- --- -----------------------------------------
/Y/Y/N/Y 4 /S/S/S/S/S/ / / / / / / / / / / / / / / /
Port Status 1 1 1 1 1 1 1 1 1 1 2
1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0
12713140-002-2 Revision E – October 2006