ETS-Lindgren FP5000 Isotropic Electric Field Probe (Archived) - Manual (Page 16)

Isotropic Electric Field Probe
HI-4422/FP2000/FP4000/FP5000
© ETS-LINDGREN L.P. – July, 2005
Revision G- Part # H-600054
16
PROBE POWER SUPPLY
A sealed rechargeable 3.6 VDC NiCd battery, which drives both
the analog and digital power supplies, powers the probe; the
HI-4422/FP2000/FP4000/FP5000 employs separate power
sources to provide isolation between the analog and digital
circuitry. With the probe switch in the ARM position, voltage
from the battery is applied to the power switch. This switch
routes the battery 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 all axis signals. This procedure is executed for all
24 ranges (four ranges, three axes per range, two antennas per
axis). When the processor receives all the zero-field signal
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