Campbell Scientific CS110 Electric Field Meter - Manual (Page 35)

CS110 Electric Field Meter
determine if results are returned as counts for a given interval (POption = 0),
or as frequency = counts/(scan interval in seconds) (POption = 1).
8.2 Measuring Electric Field
The CS110 instruction is used to perform the electric field measurement of the
CS110 and follows:
CS110(Dest,Leakage,Status,Integ,Mult,Offset)
Leakage is a variable containing the measured leakage current in nano amps
(nA) on the charge amplifier input during the CS110 electric field
measurement. A perfect unit is 0 nA. Actual units deviate from perfection
such that some have small (<< 1 nA) positive leakage current and some have
small negative leakage current. Status is a variable containing numeric codes
indicating various status conditions occurring during the measurement, as
defined in Appendix A. Integ is a parameter indicating the length of time to
perform an analog integration during the measurement, with options of 250
μs,
_50Hz and _60Hz. Integration times for _50Hz and _60Hz are 20 ms and
16.67 ms, respectively for cancellation of unwanted 50 Hz and 60 Hz noise.
Mult provides for convenient scaling within the measurement instruction, and
Offset provides for convenient incorporation of offsets. The CS110 instruction
measures the electric field utilizing the
±250 mV range. If the result is NAN,
the instruction re-measures utilizing the ±2500 mV input voltage range.
8.3 Measuring Electric Field Change
CS110Shutter(Status,Move)
Status is a variable containing the following subset of measurement status
codes given in Appendix A: status codes 1, 4, 7, 8, 9, 10, 11, 14, 15, and 16.
Move is a variable set to 1 to open the shutter and set to 0 for the
CS110Shutter instruction to close the shutter.
The CS110Shutter instruction can be utilized along with a Delay instruction to
visually verify the fully opened and fully closed positioning of the CS110
shutter, as described in Appendix D on Servicing the CS110. The
CS110Shutter instruction can also be used to implement a Slow Antenna
electric field measurement as described in Appendix E. The CS110 panel
board contains circuitry to switch in a parallel 200 M
Ω resistor with the 330 pf
feedback capacitor in the charge amplifier during execution of an open shutter
CS110Shutter instruction. This results in a charge amplifier with a 66 ms time
constant implemented as a slow antenna that can be utilized to measure
changes in electric field at rates much faster than the 5 Hz maximum rate of the
CS110 electric field measurement instruction. In the slow antenna mode the
CS110 becomes a field-change meter, meaning that the useful data becomes
the differences between the VoltDiff measurements rather than the absolute
value of each VoltDiff measurement.
8.4 Measuring Solar Radiation or Barometric Pressure
Circular connector labeled SOLAR RADIATION on the CS110 can be used
to connect up an LI200X solar radiation sensor. Alternately, a special cable,
the CS110-L BAROMETRIC PRESSURE SENSOR CABLE (17460), can be
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