User's Manual

Commissioning
Instruction manual 973 SmartRadar LT Page 31
3.4.7 Password protection
Item Name Description
W2
= Protection level 2 Enter password 2 (default password: ENRAF2)
W1
= Password 1 6 Characters, default value W1=ENRAF1. This password can
be read protected by jumper J1 on the ICU board. If this jumper
is set to position 1, the password can not be read
W2
= Password 2 6 Characters, default value W2=ENRAF2. This password can
be read protected by jumper J2 on the ICU board. If this jumper
is set to position 1, the password can not be read
DY
= Display selection One ASCII character.
For the 973 SmartRadar LT (which has no local display) item
DY
must be set to N.
EX
Exit Exit protection level.
3.4.8 Detection algorithm and special settings
Presentation of the measured level is the result of a two stage process:
• stage 1: detection
• stage 2: acceptance
Detection
The detection operates on the last radar signal captured. First peaks are detected that are above the
thresholds (items
ZA
,
ZB
and
ZP
). When there are peaks found, the level peak is selected from the list of
detected peaks (items
5D
and
5E
).
Special fuzzy logic is built in, to select the level peak from the set of detected peaks. It is important to know
that the fuzzy logic makes use of pattern recognition. Especially at very high levels it looks for patterns with
second or third order echo's. In free-space applications such echo's result from reflections against the roof
of the tank. Knowledge about he position of the roof is therefore important. Therefore, the distance from the
nozzle to the roof must be declared in item
OR
.
Acceptance
Acceptance operates around an authorised gauge level value and the ‘low product delay counter’ value.
The low product delay counter value can be set with item
FI
(default value: 75; maximum value: 99).
When an authorised gauge level is present, the value is used as the acceptance criterium for the level peaks
presented by the detection stage.
Successful acceptance of the latest level peak is used to update the authorised gauge level value.
Consecutive rejection of level peaks and / or absence of level peaks over a number of measurements equal
to the number in the low product delay counter, will result in discarding the authorised gauge level value.
When the value is discarded, the last valid value is available as level value over a period of 30 seconds.
When there is no authorised gauge level value, the level peaks presented by the detection stage are used to
built up the evidence needed to arrive at a new authorised gauge level value. A level must be present, at
least intermittent, over a number of measurements equal to the low product delay counter, before it can
become authorised.