ETS-Lindgren HI-4457 Isotropic Magnetic Field Probe (Archived) - Manual (Page 20)

HI n 4457 Manual Page — 15
6.0 THEORY OF OPERATION
Introduction
This section discusses the theory of operation and the
functions of the HI n 4457 Isotropic Magnetic Field Probe.
A high-level block diagram (Figure 6 n 1) is included to aid
the discussion. The objective is to provide information
that enhances user understanding of the design of this
probe.
System Theory
The HI-4457 Broadband Isotropic Magnetic Field Probe
uses three orthogonal sensing elements. Each of the
elements responds to the magnetic field component
aligned with the particular element. The output of the
three elements are summed as vector quantities and an
output proportional to the resultant field generated.
A microprocessor is contained in the instrumentation
housing located at the base of the probe shaft. The
microprocessor generates an output corrected for
variations in the sensor using lookup tables located in the
processor memory. The resultant value is transmitted in
an ASCII digital format through the optical cable to the
readout. The probe's self-contained power supply
employs a 3.6 VDC NiCd battery which provides up to 17
hours of continuous operation. Refer to Appendix B for
details of the ASCII output formats.
For specialized applications, you may use a computer
with an RS-232 serial port to communicate directly with
the HI-4457 using the optional HI-4413P RS-232
interface.
Archived 4/2/10