ETS-Lindgren HI-1710 Microwave Measurement System (Archived) - Manual (Page 42)

HI n 1710 Manual Page — 37
proper bias supply. Then the offset voltage of the array
is measured. The offset voltage is the signal at the
preamp output with the probe in a zero RF field. Limits on
the offset voltage check for proper probe/preamp
operation. A zero chamber option is available to minimize
the RF present at the probe head during zeroing. A
stimulus voltage is applied to the input of the first
operational amplifier stage in the preamp. This signal is
used to test the integrity of the RF signal path through
the instrument. The levels of each of the four power
supply outputs is tested on startup. If an error is
detected, an error message consisting of an error code is
displayed for one second. The self-test is then continued
and repeated until all errors have been corrected.
Microprocessor sequencing is summarized in figures 4, 5,
and 6. Figure 4 outlines the sequence of operations in the
main program loop. In Figure 5, a 450 Hz. interrupt
performs a series of operations, each at an actual rate of
45 Hz. These operations include reading RF values,
reading the keyboard, and initiating the RS-232 interrupt.
In figure 6 the RS-232 processing sequence is outlined.
Archived 4/2/10