Channel Config: Broadband Alarms

For the purpose of discussing alarms, “broadband” means maximum to minimum value, in the time-domain. Another historical term that might be used for this is “scope limits”.

This is done in the Broadband alarm tab of the Channel configuration screen, where the user can configure a single warning and alarm level for each individual channel, except IRIG, Tacho and Speech channels.

The Limit is the maximum value of the channel, i.e. for a 10 V ADC Input Range and a 1 mV / EU calibration, the limit would typically default to 10,000 EUs. The Warning Level defaults to 80% of the Limit and the Alarm Level defaults to 90% of the limit.

It is also possible to change the broadband setting while scanning, from the HawkEye. From the overview page, right-click on a channel name in the bar chart:

Alternatively, use the settings panel:

In the Hawk GUI, the user also has four additional buttons available from the “BB Alarms” tab:

  1. An alarms file can be loaded from the local safety files directory, by clicking the Load Alarms button.
  2. A set of alarms can be saved to file by clicking the Save Alarms button. This saves and applies the current alarms to the configuration ready for acquisition and also saves a copy in the local safety files folder as setup on the Preferences screen
  3. An alarms file can be deleted by clicking the Delete Alarms button, whereby the user will be able to select which file to delete via a similar window to the Load Alarms window.
  4. The final button is the Defaults button that resets, for each channel, the limit level to the max EU (computed based on the channel current calibration information).Warning and alarm level are defaulted to respectively 80% and 90% of the limit.

Processing the Alarms

The peak service is responsible for monitoring the broadband alarms. When the peak value computed for a channel is detected to have gone over the warning or alarm level, it is reported in real time to the HawkEye.

Displaying the Alarm State

Any instrument in the Hawkeye which displays a channel will show:

  • Orange background if the channel peak level is above the warning level defined.
  • Red background if the channel peak level is above the alarm level.

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