Comtech EF Data CDM-750 - Manual (Page 91)

CDM-750 Advanced High-Speed Trunking Modem Revision 2
Front Panel Operation MN-CDM750
5–13
Item Description
RxPLL
(Alarm) The Rx Clock PLL is railed high or low indicating that the Rx Clock Source is
substantially different than the rate of incoming data.
RxOF
(Alarm) Rx Overflow indicates that the traffic received by the demod is exceeding the clock
RxClock setting and is therefore overflowing the buffer causing the buffer to re-center and
take a data hit.
RxUF
(Alarm) Rx Underflow indicates that the traffic received by the demod is not keeping up with
the clock RxClock setting and is therefore underflowing the buffer causing the buffer to re-
center and take a data hit.
ExtClkInRange
External Clock In Range indicates that the External Clock is selected by either the TxClock
or RxClock but the clock rate on J8 does not meet the expected rate by the modem. Note:
When ExtClkAct IS NOT in an Alarm or Fault condition but the ExtClkInRange IS in Alarm or
Fault condition, it is an indication that the clock source rate and the modem’s programmed
External Clock rate are different.
Using the TxPLL menu as the example:
Tx Pll Mask:Fault
Alarm Fault Mask Fault-Tx On
The top line notes the active mask selection. On the bottom line, use the W X arrow keys to
select Alarm, Fault, Mask, or Fault‐Tx On, and then press ENTER. (For the RxPll, RxOF and RxUF,
menus, only Alarm, Fault, and Mask are provided.) Note the following:
Mask Type Description Redundancy Switchover and Tx Mute
Alarm Alarms can be viewed from the Monitor:
Live Alarms menu (Sect.5.2.4.1). Alarms
cause the Unit Status LED to turn AMBER.
An alarm WILL NOT cause a redundancy switch
and WILL NOT mute the Tx carrier
Fault Faults can be viewed in the Monitor:
Stored-Events log (Sect. 5.2.4.2).
Faults cause:
• The Unit Status LED to turn RED
• The J1 Alarm Connector to show a
Fault
A fault WILL cause a redundancy switch and
WILL mute the Tx carrier
Mask Masking the event has the effect of ignoring
the event – it can no longer be logged and
is not seen in any menu.
Mask WILL NOT cause a redundancy switch
and WILL NOT mute the Tx carrier
Fault-Tx On Faults can be viewed in the Monitor:
Stored-Events log (Sect. 5.2.4.2).
Faults cause:
• The Unit Status LED to turn RED
• The J1 Alarm Connector to show a
Fault
A Fault-Tx On WILL cause a redundancy switch
and WILL NOT mute the Tx carrier