3-4
Analog OUTput:
When the analog output is activated, the indicator “OUT” is visible accompanied by either the
DC (---) or the AC (~) symbol. This feature is only functional on the Model 4190. By pressing the SHIFT–
OUTPUT key sequence the meter will switch between output off, DC OUT, or AC OUT. See figure 3-3. In DC
OUT mode the signal is calibrated to 2.0Vdc full scale. In AC OUT the signal is a waveform calibrated to
1.0VacRMS full scale and rolls off at higher frequencies due to the filtering in the output circuit. This is typically
±3% from about 30 to 500Hz, decreasing to -3dB at 20 and 2000Hz. See Fig. 3.5 for a typical response curve.
AC output (~) is only available in the single axis modes. In XYZ mode only a DC analog output is available.
Typical Frequency Response Curves
-30%
-25%
-20%
-15%
-10%
-5%
0%
5%
10
100
1000
10000
Frequency, Hz
%
E
rro
r
X,Y Display
Z Display
Analog Out, AC Mode
Figure 3.5
Auto-Ranging Feature:
The 4100 series meters will automatically switch to the high range when a field level of
198mG (19.8µT) is exceeded. If the meter is in the high range, it will switch to the low range when the level
drops below 188mG (18.8µT). The only indication of range setting is the location of the decimal point and the
corresponding full scale value of the display.
If the 4100 series meter is being controlled remotely, the range may be set to low, high or auto-range via
software commands.
Advanced Measurements
Basic ELF gaussmeter operational procedure is found in Section 1 of this manual. When conducting ELF field
measurements, one should take advantage of the features the 4100 series meters have to offer.
When conducting a measurement the user can use the RELATIVE feature to compare field strength between
different devices or locations. The user can take an initial reading at a certain location and select the relative
option, then move the meter to a different location and the difference will be displayed. When performing relative
measurements, the meter may display negative readings. This means the field strength has dropped below the
original level and does not mean the field has changed polarity or direction.
The HOLD function will retain the maximum or minimum reading until the held reading is RESET or the HOLD
mode is turned off. This is useful for monitoring the magnetic field level at a particular location during a long
period of time. Once the feature is activated, the display update rate will appear to have slowed down or even
stopped. This is because only the newest minimum or maximum field levels, depending on the MIN or MAX
setting will be displayed. Placing the meter in a weaker or stronger magnetic field which crosses the previous
MIN or MAX level will change the reading. Perform a RESET to reset the held reading to the present field level.
