Inficon Sion, Operating Manual, Page: 41 / 52

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Sion Operating Manual
Chapter 2
How The Sion Works
2.1 Theory of Operation
The Detector samples the electric and magnetic fields surrounding the power
transmission strap. A capacitive pickup generates a RF signal proportional to the
magnitude of the voltage present on the strap, this is referred to as the Voltage
Output. An inductive pickup generates a RF signal proportional to the magnitude
of the current flowing in the strap, this is referred to as the Current Output. The
Detector circuitry is passive with no frequency selection or band limiting.
Circuitry in the Converter compensates for the Detector's inherent frequency
response, resulting in a relatively flat Detector output level versus frequency.
Following the leveling circuit, the signals are applied to a log amp detector that
generates a voltage proportional to the log of the magnitude of the RF Current and
RF Voltage signals. The detector output drives an amplifier stage that provides
adjustment of the gain and offset of each channel. For better noise immunity, the
scaled Voltage and Current Outputs are buffered by a current source before being
sent down the cable to the Breakout box.
In the Breakout box, the signals are converted back to voltage signals and made
available at the output connector as double-ended signal pairs.
The data acquisition board in the PC utilizes a multiplexer to connect one signal
pair at a time to its analog to digital converter. The software (FabGuard) running on
the PC configures the data acquisition board to measure the appropriate channels.
The digital data from the desired channels is then stored for further data
processing.