VEGA VEGASCAN 850 - Manual (Page 87)

VEGASCAN 850 87
Setup - Sensor adjustment with the adjustment module MINICOM
3. Meas. conditions
Here you inform each sensor under which
application conditions the measurement is
carried out, e.g. measurement in gas compo-
sitions deviating from air, which will influence
the running time of the ultrasonic signals or if
a liquid (hard echo) or a solid (weak echo)
should be measured.
4. 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 note 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.
5. 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 plan 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.
6. Processing/Scaling of the sensor
display
(see menu plan)
Ampl.:
XX dB
S-N:
XX dB