SVC GROUP ASM1024-600, Руководство пользователя

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SVC WIRELESS EXTERNAL DATA INTERFACE 4 CHANNEL USER MANUAL REVISION 1.0
Figure 16 External Data Display After Reference Scan
This shows that the PAR sensor’s downwelling radiance value was 10440 units during the most recent
Reference Scan. The “Last Scan” indicates that we have not yet acquired any WEDI-4 sensor data
associated with a Target Scan since our last Reference Scan.
Now, just prior to acquiring an actual Target Scan, the operator may first press the “Ext Data Scan”
button, in order to test if the current downwelling radiance is still the same as it was during the most
recent Reference Scan. This is shown below:
Figure 17 External Data Display After Ext Data Scan
This shows that the current downwelling radiance (“Last Scan Field”) is 10433 units, or 99.9% when
compared to what it was at the time of the last Reference Scan. So a Target Scan could be quickly
acquired right now - a new Reference Scan is not required.
The “Last Scan” field is also updated whenever the Target Scan button is pressed. This allows the
operator to immediately know when a Target Scan must be discarded, because downwelling radiance
has changed too much. This situation is shown below:
Figure 18 External Data Display After Target Scan - Cloud Cover!
This shows that the target we just acquired had only 8131 downwelling radiance units, or 77.9% when
compared to what it was during the prior Reference. This Target Scan may have to be discarded, since
the absolute reflectance calculation from this target data will be incorrect due to the changed lighting
conditions between the Reference and Target Scan.
In summary:
•
The “Ext Data Scan” button immediately updates the “Last Scan %” field, which may be
examined just prior to a target scan, in order to know whether conditions are still suitable for
a new target.
•
The “Target Scan” button also updates the “Last Scan %” field, which may be examined
after a target scan to judge whether the target scan contains good spectral data, or should be
discarded.