ETS-Lindgren HI-3510 RF Radiation Badge Broadband Electromagnetic Radiation Detector (Archived) - Manual (Page 21)

Page — 16 HI n 3510 Manual
high common mode rejection and low DC drift. The high
level output of this circuit is connected to a micro
controller which has a built in A/D converter. The
amplifier has two gain ranges that are controlled by the
micro controller.
A self-contained test signal is constantly applied to the
RF detector. Should a fault occur in this circuit, a fault
signal is generated through the DC amplifier which then
generates a fault bit to the micro controller.
The analog output from the DC amplifier is digitized by
the micro controller's A/D converter. The reference
voltage for the A/D converter is generated from a band-
gap reference diode which provides excellent long term
stability. The micro controller then controls the
measurement rate for instantaneous or average
measurements, amplifier ranges, LCD display, fault
indications and low battery signals. It stores and
computes the data for the six minute average readout and
stores the alarm warning level trip point.
4-4 RF SHIELDING
To enable accurate operation of the sensitive circuits
within the RF Radiation Badge in the presence of RF
fields, an array of shields and absorbers is used. The
circuits are contained within a Faraday shielded area
which is then covered by a graded absorber to minimize
field disturbances.
Archived 4/2/10