ETS-Lindgren HI-3604 ELF Survey Meter - Manual (Page 16)

Page -- 8 HI-3604 Manual
The HI-3604 can be user programmed to indicate in either units
of milligauss/gauss, milliamperes/amperes per meter, or
nano/micro teslas. Refer to section 3.0 OPERATION for further
details. The HI-3604 indicates magnetic field flux density in
units of millgauss (mG) and gauss (G). Most ELF reports and
research in the US today use these units. The SI unit of
magnetic field flux density is the tesla (T). Environmental ELF
magnetic field measurements are generally reported in units of
microtesla ( : T) or nanotesla (nT).
Magnetic field measurements in free space may be converted to
different units through the following relations:
1 mG = 1000 : G = 80 mA/m
1 T = 10000 G
1 mT = 1000 : T = 800 A/m
Figures 2-1 and 2-2 illustrate typical frequency response plots
for electric and magnetic field strength. The HI-3604 is
designed to provide a flat response over the range of
frequencies corresponding to the 50 or 60-Hz power line
frequency and the first several harmonics. The tailored low-
frequency characteristic to the response helps reduce magnetic
field response to movement of the sensor in the earth's
constant magnetic field.
The bandwidth of the true RMS detector is a function of the
amplitude of the applied field. The bandwidth of the HI-3604 is
also related to the particular measurement range selected.
Thus, for a specific measurement, the bandwidth exhibited may
be greater or lesser than shown in Figures 2-1 and 2-2.
Generally, maximum bandwidth, and thus accuracy, is obtained
for any given field strength by selecting the lowest range (and
scale) that still permits an on-scale reading.
The HI-3604 also provides for monitoring the waveform of the
signal coming from the sensor preamplifier circuit in the input