BARTINGTON INSTRUMENTS
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Bartington Instruments can supply cables for connection of the sensor to the PSU1, Magmeter,
SCU1 and Spectramag-6.
6.2. Connecting power
Caution:
Check that the polarity of the supply is correct. The power supply should
be connected to the sensor before the supply is energised as this prevents high
surge currents which could cause damage. Apply the positive and negative supplies
simultaneously and avoid leaving the sensor connected to one polarity only.
6.3. Electromagnetic compatibility
Note:
The Mag585 and Mag592 are not shielded for immunity from, or emission of,
electromagnetic fields. Any shield placed around the sensor will limit the bandwidth of the
sensor response. The emissions generated are at a low level with a primary frequency of
12.8kHz, being the frequency of the energising field of the sensor. The sensor is required to
respond to magnetic fields within the specified frequency band.
Note:
Ensure that the sensor is not operated in areas where a high electromagnetic field
exists, even if the frequency is above the bandwidth of the sensor, as false information may
appear due to aliasing. This effect is seen in data acquisition systems when the frequency
of sampling is lower than the frequency of the signal which is being sampled. It may
produce apparent signals at lower frequencies than the noise, which may be within the
frequency band of the sensor. Similarly, do not place the sensor near to any equipment
which may be affected by the fields produced by the sensor excitation.
6.4. Performance
6.4.1. Signal processing
For different applications it may be necessary to process the signal from the sensor in different
ways.
a. In order to increase the sensitivity of the recording system, it may be necessary to back-
off the earth’s field and amplify only the changes in the field from the current value. This
requires a high-pass filter, which could be a simple capacitively coupled arrangement or a
multi-pole filter to provide a steep roll-off characteristic. These features are all present in
the SCU1 signal conditioning unit.
The output from all fluxgate sensors will contain noise from the driving electronics. For
the Mag585 and Mag592 this noise is at 12.8kHz, which is well above the bandwidth of the
sensors. Where low noise operation is required, a filter should always be provided to reject
the noise which lies outside the band of interest.
