Table 4. Protection Configuration Option Settings
Protection Options | Settings | Description |
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Protection Mode | Auto | System automatically switches from Main to AUX with no user intervention. |
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| Switch is initiated by loss of sync on Main or exceeding BER Threshold. |
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| Alarms and switchover notification are generated via the SCU. Auto Mode |
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| also allows reversion back to Main once sync is reestablished or the error |
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| count drops below the BER Threshold. |
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| Auto Hold | Auto Hold provides system protection identical to Auto Mode, except that |
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| reversions are not allowed to the Main without user intervention. Once |
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| switchover has occurred to the AUX circuit, data can only be reverted by |
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| modifying any option on the terminal screen or by the pushbutton on the |
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| faceplate of the LTU. |
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| Manual Main | Manual Main requires manual switchover to the AUX circuit by user |
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| intervention. Switchover can be accomplished via the faceplate pushbutton |
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| or the terminal screen. The SCU will make notification of a Main circuit |
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| failure, but will not report switchover until the data is manually switched to |
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| the AUX circuit. |
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| Manual AUX | Data is manually forced to the AUX circuit and will remain there until the |
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| mode is changed via the terminal screen or by pushbutton on the faceplate. |
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| All other option settings are ignored while in this mode. |
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| In the Manual Disable mode, the Main and AUX circuits act as two |
| Manual Disable | independent units. Separate data can run on either circuit without affecting |
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| the operation of the other. All other option settings are ignored while in this |
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| mode. |
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Minimum | Defines the minimum time that data will remain on the AUX circuit. This | |
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| option is only valid when in Auto or Auto Hold Protection Modes. |
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BER Threshold | Allows the user to set the Bit Error Rate that will cause switchover from the | |
| Main to AUX circuit when exceeded. BER Threshold can also be set from | |
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| the Main card's protection configuration and should coincide with the |
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| settings used on the AUX card. |
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BER Interval | 5, 10, 15 minutes | Defines the interval over which errors will accumulate for comparison with |
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| the BER Threshold setting. BER Interval can also be set from the Main card's |
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| protection configuration and should coincide with the settings used on the |
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| AUX card. |
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Defines duration of locking to the AUX circuit upon reaching the Switch to | ||
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| AUX Limit. |
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Switch to AUX | Limit | Defines the number of times switch can occur from Main to AUX over the |
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| defined Locking Check Interval before the system is locked to the AUX |
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| circuit for the defined Locking Hours. |
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Defines the interval over which the Switch to AUX Limit is compared before | ||
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| locking in the data to the AUX circuit for the Locking Hours duration. |
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Section | 15 |