ETS-Lindgren FP5080 Isotropic Electric Field Probe (Archived) - Manual (Page 17)

Isotropic Electric Field Probe
© ETS-Lindgren, June, 2005
Revision F, Part # 600057 17
PROBE OPERATION
Receiver commands to the probe consist of the following:
• Sending reading
• Switch range
• Read battery voltage
• Zero
• Read temperature
• Enable
axis
• Set sleep timer
The signal flow within the probe is shown in the block diagram.
To measure field strength, three mutually orthogonal dipole
antennas (one per axis) are used to provide an isotropic
response to the ambient field. The signal from each axis is fed
to a Schottky diode detector operating in its Square-Law region.
After filtering, the signals generated by each axis are added
vectorially: the result is fed to the instrumentation amplifier,
whose output feeds the selectable range/offset stage.
NOTE: The HI-4450/FP2080/FP4080/FP5080 does not
allow the option of measuring on an individual axis: all
three axes are active at all times. Consequently, the
change axis commands have no effect.
For each of the four ranges, the selectable range and offset
stage provides a coarse analog zero for the measured signal.
The output of the range/offset stage is fed to the A/D multiplexer,
then to the analog-to-digital (A/D) converter itself.
After acquiring the composite three-axis signal, the
microprocessor commands the A/D multiplexer to read the
battery voltage and temperature sensing lines.
Data from the A/D converter is fed to the microprocessor, which
transmits it to the receiver.
The EEPROM stores all calibration data for the probe.
Archived 4/02/10