Vaisala RVP900 - Available Subcommands in Pr; Table 39 Pr Subcommands

The purpose of the Pr power spectrum is to check for spurious interference in the IF signal
from the radar receiver. View the spectrum with the transmitter turned o, and with the
starting range moved out so that the burst samples are not mixed with the receiver data.
The power spectrum is computed using the complete interval of raw IF samples which,
depending on the chosen time span, may contain many hundreds of points. The frequency
resolution of the Pr spectrum can be quite
fine to make it possible to discern any interfering
frequencies with some detail.
The Pr spectrum plot shows a 0 Hz peak from any DC oset in the A/D converter, and is
consistent with how the DC oset is presented in the Pr sample plot.
Both plots preserve the DC component of the IF samples so that it can be monitored as part
of the routine maintenance of the receiver system. This is one of the few places in the
RVP900 menus and processing algorithms where the DC term deliberately remains intact.
6.7.2
Available Subcommands In Pr
These subcommands change the start time and span of the IF sampling window, and alter
the format of the display.
The list of subcommands is printed on the TTY:
Available Subcommands within Pr :
L/l & R/r Start range Left/Right
T/t Plot time span Up/Dn
V/v Number of spectra averaged
Z/z Amplitude zoom
<space> Alternate Plots
> and < Start/Stop logging to rvp9-pr.log
% Toggle between IF input channels
- Single Step
Table 39
Pr Subcommands
Command Description
L/l & R/r
Shift left and right the starting point of the window of IF samples. The lower case
commands shift in 0.25 μsec steps, and the upper case commands use 10 μsec steps.
The starting point is displayed both in microseconds and kilometers on the TTY, and is
not allowed to be set earlier than range zero.
T/t
Increments or decrements the time duration of the window of IF samples. The window
is not allowed to become shorter than the impulse response length of the FIR filter,
since that would preclude calculating even a single LOG power point. The value is
reported in microseconds on the TTY, and the largest permitted span is 50 μsec.
V/v
Increments or decrements the number of power spectra that are averaged together to
create the plot. The count ranges from one (no averaging) to 25, and is reported on the
TTY as Navg.
RVP900 User Guide M211322EN-J
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