VEGA VEGAPULS 45 VBUS - Manual (Page 73)

VEGAPULS 42, 44 and 45 – VBUS 73
Ampl.:
XX dB
S-N:
XX dB
5. Measurement in a standpipe
This adjustment is only necessary if the
sensor is mounted on a standpipe (surge or
bypass tube). When measuring in a
standpipe, the distance must be sounded
and the measured value display (can deviate
a few percentages from the sounded value)
must be corrected according to the
sounding. Then the sensor corrects future
running time shifts of the radar signal in the
standpipe and displays the correct level in
the standpipe (meas. tube).
6. Operating range
Without special adjustment, the operating
range corresponds to the measuring range.
The measuring range has already been ad-
justed with the min./max. adjustment. Gener-
ally it is useful to choose a slightly bigger
(approx. 5 %) operating range than measur-
ing range.
Example:
Min./max. adjustment: 0.500 … 3.500 m;
adjust operating range to approx.
0.400 … 3.600 m.
7. Meas. conditions
(see MINCOM menu schematic)
8. False echo storage
A false echo storage is always useful when
unavoidable false echo sources (e.g. struts)
must be minimised. By creating a false echo
storage, you authorise the sensor electronics
to record the false echoes and save them in
an internal database. The sensor electronics
treats these (false) echoes differently from
the useful echoes and filters them out.
Adjustment with MINICOM or VEGAMET
9. Useful and noise level
In the menu
you get important information on the signal
quality of the product echo. The higher the
"S-N" value, the more reliable the measure-
ment (menu schematic MINICOM).
Ampl.: means amplitude of the level echo in
dB (useful level)
S-N: means Signal-Noise, i.e. the useful
level minus the level of the back-
ground noise
The bigger the "S-N" value (difference be-
tween the amplitude useful level and the
noise level), the better the measurement:
> 50 dB
Measurement excellent
40 … 50 dB Measurement very good
20 … 40 dB Measurement good
10 … 20 dB Measurement satisfactory
5 … 10 dB Measurement sufficient
< 5 dB Measurement poor
Example:
Ampl. = 68 dB
S-N = 53 dB
68 dB – 53 dB = 15 dB noise level
53 dB signal level difference indicates very
high measurement reliability.
10. Conditioning/Scaling of the sensor
display
The menu item "Signal conditioning" in the
MINICOM menu relates only to the sensor
display and will be overwritten by adjust-
ments in the signal conditioning instrument.
11. Outputs
(see operating instructions VEGAMET)