ETS-Lindgren FP2083 Isotropic Electric Field Probes (Archived) - Manual (Page 18)

Isotropic Electric Field Probes
HI-4453/FP5083/FP4083/FP2083
© ETS-LINDGREN L.P. – June 2005
Rev. F, P# H-600064
18
PROBE POWER SUPPLY
A sealed rechargeable 3.6 VDC NiCd battery, which drives both
the analog and digital power supplies, powers the HI-
4453/FP5083/FP4083/FP2083 probe. Separate power sources
provide isolation between the analog and digital circuitry. With
the probe switch in the “ARM” position, battery voltage is applied
to the power switch, which routes this voltage to the power
supply, enabling the microprocessor. A timer circuit controls the
power switch. The timer monitors the fiber optic connector input
line to determine whether the probe has received a command
during a specified period (several seconds). If no command is
received during this period, the timer signals the power switch to
disable the power supply and the microprocessor. In essence,
the probe goes dormant to conserve battery power; only the fiber
optic input circuitry remains active in order to detect new
commands. When the next command from the receiver reaches
the probe, power is reapplied automatically and the processor is
reactivated, "waking up" the probe.
NOTE: The probe uses volatile random access
memory (RAM). If, for any reason, power to the
probe is lost, the probe must be re-zeroed.
Zeroing
When the receiver sends a zero command, the probe must be in
a zero field environment. This is because the zero command
causes the multiplexer (via the processor) to perform a normal
read cycle on the composite axis signal. This procedure is
executed for all ranges. When the processor receives all the
zero-field values, it stores them in a special register; these
values are subtracted from all subsequent measurements.
Therefore, a probe that is zeroed while it is not in a zero field
environment will give erroneous readings.
Archived 4/2/10