OPERATION |
Alarm Reporting
The PMU reports alarms to the Site Controller computer in the status message replies to the
Transmitter Alarms
When the Site Controller computer receives a transmitter alarm from the PMU, the Site Controller computer takes the following action:
∙Stops assigning that transmitter to system calls.
∙Continues to assign that transmitter to test calls.
∙Sends a clear alarm message to the PMU telling it to clear all alarms so that only new alarms will be reported in the next status message.
∙Sends the alarm information (transmitter channel number) to the System Manager.
However, if three or more transmitter alarms are reported in the same status message, the Site Controller computer will ignore all the alarms in that status message. It is felt that this condition is more likely to be a mistake than the truth (it would require three transmitters to be keyed almost at the same instant and all three transmitters to indicate a power problem). If any of these alarms really are valid, they will be reported the next time the associated transmitters are assigned.
As soon as the PMU no longer reports a transmitter alarm during a test call to a previously alarmed transmitter, the Site Controller computer takes the following action:
∙Resumes assigning that transmitter to system calls.
∙Continues to assign that transmitter to test calls.
∙Sends the alarm cleared information (transmitter channel number) to the System Manager.
There may be a noticeable delay between when the problem is corrected and the System Manager sees the transmitter alarm indication cleared, because the alarm condition is not considered cleared until a successful test call has been placed to that transmitter. This delay may be reduced by doing one or both of the following:
∙Set the Background Testcall Interval to the minimum of one minute. This may be specified in the Site Controller computer’s Personality PROMs
(must be factory programmed), or
∙Switch the transmitter off (12V power supply), then back on, after fixing the transmitter alarm problem. This will cause the next test call to be placed to that transmitter.
Antenna Alarms
When a status message from the PMU contains an antenna alarm, the Site Controller computer takes the following action:
∙Sends a clear alarm message to the PMU telling it to clear all alarms so that only new alarms will be reported in the next status message.
∙Counts the reported alarms for this antenna and the number of polling cycles.
∙Sends the alarm information (antenna number) to the System Manager if two or more alarms are received for this antenna during any three consecutive polling cycles.
As soon as that antenna stops causing an alarm, the Site Controller computer takes the following action:
∙Sends the alarm cleared information (antenna number) to the System Manager.
Excessive Alarms
If the quantity of transmitter channels that are not in use for system calls (due to PMU transmitter alarms) exceeds 50% of the total number of equipped transmitter channels, the Site Controller computer takes the following action:
∙Suspends the practice of using transmitter alarms from the PMU to take transmitter channels out of use for system calls (and reinstates those taken out of use up to that point).
∙Continues to assign all transmitters to test calls.
∙Sends a clear alarm message to the PMU telling it to clear all alarms so that only new alarms will be reported in the next status message.
∙Sends the alarm information (transmitter channel number) to the System Manager.
The Site Controller computer will continue to use the transmitter channels for which the PMU is still reporting alarms until all transmitter alarm conditions are corrected.
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