F.W. BELL 8000 Series Gauss/Tesla Meter Instruction Manual
Section 6 – Flux Density Measurement
6-6
Frequency Compensation in AC Mode
To obtain accurate ac measurements using frequency compensation, the ac
field must have a frequency greater than 5 Hz, and depending on the
selected range, a minimum magnitude according to
Table 6-2.
Table 6-2 Minimum Magnitudes for Rated AC Accuracy
Range
Minimum Magnitude
Low Field Probe
Mid Field Probe
High Field Probe
300.000 mG (30.0000
µ
T)
30.0000 G (3.00000 mT)
300.000 G (30.0000 mT)
20% Full Scale
3.00000 G (300.000
µ
T)
300.000 G (30.0000 mT)
3.00000 kG (300.000 mT
6% Full Scale
N/A
3.00000 kG (300.000 mT)
30.0000 kG (3.00000 T)
4% Full Scale
N/A
30.0000 kG (3.00000 T)
300.000 kG (30.0000 T)
2% Full Scale
If the measured magnetic field is less than the “Minimum Magnitude” shown
in Table 6-2, fourth column; the frequency of the magnetic field may not be
measured accurately resulting in magnitude errors that do not meet the
specified accuracy.
AC MODE
OPERATION
AC Mode Analog Filtering
While operating in AC mode one of six analog filter modes can be selected as
shown in Table 6-3. These filters affect the displayed reading and analog
outputs.
As shown in Table 6-3 the Full Bandwidth frequency filter selection utilizes the
full bandwidth of the 8000 Series Gaussmeter. The other filter selections can
be used to narrow or focus the bandwidth of the meter’s analog amplifiers to
minimize influence from noise or other unintentional signals.
A selection called No Corrections is also available. This filter mode sets the
meter to its full bandwidth but does not apply AC frequency correction factors.
This setting can be useful when measuring signals that do not have stable
fundamental frequency content, low duty-cycles or capturing transient events.
Internally the meter also uses these filter selections to determine the best data
sampling and averaging rates to generate the most accurate RMS calculations
and readings.
To avoid additional reading errors care should be taken to avoid using any
particular filter with input frequencies close to the filter limits. Driving the input
with signal frequencies at or near these frequencies limits the effectiveness of
internal correction factors and may reduce accuracy.
