User manual

Code: ENIGMA III User Manual
Edition: 1 Revision: 4
Date: 19/12/2008
Page: 66/97
6.22 Threshold algorithms.
Enigma III generates the following moments:
● Reflectivity Z
● Velocity V
● Spectrum width W
● Uncorrected reflectivity U
There are four threshold checking algorithms in Enigma III:
● CCOR
● SQI
● RHOHV
● NOISE
These algorithms can be combined using boolean functions AND and OR. Internally, Enigma III checks
above thresholds and creates a value that describes the results.
● If calculated CCOR less or equal then CCOR threshold, bit 0 is set.
● If calculated SQI less or equal then SQI threshold, bit 1 is set.
● If calculated RHOHV less or equal then RHOHV threshold, bit 2 is set.
● If calculated SNR greater or equal then NOISE threshold, bit 3 is set.
This value is an index in range 0-15 in the 'pass table'. The unsigned 16 bit word from the table is a set of
bits. If some bit is set, the appropriate moment is passed, otherwise is thresholded. There is a relation
between bit number in the word and moment:
● Z - bit 0
● V - bit 1
● W - bit 2
● U - bit 3
Other bits are reserved for dual polarization moments.
The threshold table is stored in the parameter 'thresholdFlagsTable'.
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