Chapter 5 _______________________________________________________ Plot-Assisted Setups
VAISALA______________________________________________________________________ 155
The P command lets you decide whether the 25-bit
word represents a numeric AFC span that is mapped
into pins via the pin-map table in the Mb menu; or
whether it represents those pins directly. The printed
hex test value will be followed either by "(Bits)" or
"(Pins)" accordingly. When in "Pins" mode, the "0" key
toggles Pin-1, the "1" key toggles Pin-2, etc. When in
"Bits" mode, the "0" key toggles whatever pin or pins
have been designated to be driven from Bit-0 of the
numeric AFC. The "Pins" mode is useful when you are
doing the initial electrical tests of the wiring of each pin.
After the pin wiring has been verified and the Mb
mapping table has been created, then the "Bits" mode
allows you to test the complete digital AFC interface.
# The # command results in a printout of the coefficients
of the current FIR filter. The values are scaled by the
coefficient with the largest absolute value, so that they
all fall within the 1 to +1 range. This detailed
information may be used to model the behavior of the
filter for point targets that fall in between discrete range
bins, for example, as will happen when performing a
radar sphere calibration. See Section 6.1.1 FIR
(Matched) Filter on page 183 for the exact definition of
these coefficients.
$ The $ command performs an automatic search for
optimal (DC gain of zero) filters in the vicinity of the
current one. As an example, suppose that we wanted an
optimal filter that was approximately 2.2 µsec long and
650 KHz wide. We would first use the I/i and W/wN/n
subcommands to manually move to that starting point.
Typing "$" would then print a dialog line in which the
search span length and width are chosen. You may keep
the indicated values or type in new ones, just as for all
RVP900 setup questions. The search begins when the
spans are accepted.
The search procedure may require a few seconds to a
few minutes, depending on the length and width spans
that are being scanned. During this time, a progress
message is printed showing the length and width
currently under examination. You may type Q to abort
the search and retain the original filter settings. When
the search completes normally, it will print "Done" and
replace the old filter settings with the best ones that
could be found.
To Next Page
Loading...