Chapter 5 _______________________________________________________ Plot-Assisted Setups
VAISALA______________________________________________________________________ 153
5.4.2 Available Subcommands Within Ps
The list of subcommands is printed on the TTY:
Frequency span of the plot is 36.0 MHz to 72.0 MHz.
Available Subcommands within 'Ps':
These subcommands change the design of the matched FIR filter, assist
with calibration of the AFC loop, and alter the format of the display.
I/i Impulse response length Up/Dn
N/n & W/w Filter bandwidth Narrower/Wider
U/u & D/d MFC Up/Down (On/Off '=' , Test '|')
A/a & S/s Aperture & Start of AFC window
# Print filter coefficients
$ Search for an optimal filter
V/v Number of spectra averaged
Z/z Amplitude zoom
<space> Alternate Plots
% Toggle between dual receivers
- Single Step
I/i The I command increments or decrements the length of
the matched filter's impulse response. Each keystroke
raises or lowers the FIR length by one tap. Often the
matched filter's characteristics can be very much
improved merely by changing the FIR length by one or
two taps. Be sure to experiment with this as you design
your filter.
N/n & W/w The N and W commands change the passband width of
the matched filter, making it narrower or wider. The
lower case commands make changes in 1 KHz steps,
and the upper case commands use 100 KHz steps. The
value is reported on the TTY as "BW". Often a small
change in passband width will shift the exact locations
of the filter's zeros, and possibly improve the DC
rejection.
U/u & D/d The U and D commands implement the Manual
Frequency Control (MFC) override, and allow the
RVP900/IFDs AFC output voltage to be manually set to
any fixed level. The lower case commands make
changes in 0.05 D-Unit steps, and the upper case
commands use 1.0 D-Unit steps. The value is reported
on the TTY as "AFC".
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