F.W. BELL 8000 Series Gauss/Tesla Meter Instruction Manual
Section 6 – Flux Density Measurement
6-22
Analog
Outputs
(Continued)
Flux Density Range and Output Voltage Range
Full scale of the present flux density range always corresponds to the full
scale setting for the analog output voltage range. For example, if the full
scale flux density range is 30 gauss and the full scale analog output voltage
range is 3 volts; then a reading of 30 gauss will produce a voltage of 3 volts
at the output. A reading of -20 gauss will produce a voltage of -2 volts at the
output.
Using Analog Outputs with Auto Range
When using auto range and the analog output features together, the
following situation can occur. Suppose the present range is 3 kG and the
present reading is +2.8 kG. The analog output will be +2.8 VDC. The signal
then increases to +3.2 kG, which would force an automatic change to the 30
kG range setting. The analog output will now be +0.32 VDC because of the
range change. This can lead to problems if the analog signal is being used
to make decisions, because there is no indication that a range change has
occurred. In these situations it is best to select a fixed range that covers the
expected flux density span.
Using the Vector Summation Analog Output
Full scale for the vector summation output will correspond to the full scale
range of the channel with the highest range setting. For example, if the
range for channels 1 and 2 are set to 30 gauss, and channel 3 is set to 300
gauss; the vector summation will associate 300 gauss with its full scale
output voltage setting.
Vector summation also allows the output voltage to exceed the full scale
value. This allows the possible range of vector magnitudes to be fully
represented at the analog outputs. As an example, consider all three
channels set for the 300 gauss range and each channel measuring a flux
density of 300 gauss. In this situation the vector magnitude would be
calculated as follows:
G
G
G
G
V
SUM
6
.
519
)
300
(
)
300
(
)
300
(
2
2
2
=
+
+
=
With a full scale analog output voltage setting of 3 volts, the output voltage
would be approximately 5.2 volts.
Note: In all cases the maximum output voltage is limited to 10 V.
