Vaisala RVP900

Chapter 4 _____________________________________________________ TTY Nonvolatile Setups
VAISALA______________________________________________________________________ 129
IF increases for an approaching target: YES
The intermediate frequency is derived at the receiver's front end by a
microwave mixer and sideband filter. The filter passes either the lower
sideband or the upper sideband, and rejects the other. Depending on which
sideband is chosen, an increase in microwave frequency may either
increase (STALO below transmitter) or decrease (STALO above
transmitter) the receiver's intermediate frequency. This question influences
the sign of the Doppler velocities that are computed by the RVP900.
PhaseLock to the burst pulse: YES
This question controls whether the RVP900 locks the phase of its
synthesized "I" and "Q" data to the measured phase of the burst pulse. For
an operational magnetron system this should always be "YES", since the
transmitter's random phase must be known in order to recover Doppler
data. The "NO" option is appropriate for non phase modulated Klystron
systems in which the IFDR sampling clock is locked to the COHO. It is
also useful for bench testing in general. In these "NO" cases the phase of
"I" and "Q" is determined relative to the stable internal sampling clock in
the IFDR module.
Minimum power for valid burst pulse: -15.0 dBm
This is the minimum mean power that must be present in the burst pulse
for it to be considered valid, that is, suitable for input into the algorithms
for frequency estimation and AFC. The reporting of burst pulse power is
described in Section 5.3 Pb — Plot Burst Pulse Timing on page 143; the
value entered here should be, perhaps, 8 dB less. This insures that burst
pulses will still be properly detected even if the transmitter power fades
slightly.
The mean power level of the burst is computed within the narrowed set of
samples that are used for AFC frequency estimation. The narrow
subwindow will contain only the active portion of the burst, and thus a
mean power measurement is meaningful. The full FIR window would
include the leading and trailing pulse edges and would not produce a
meaningful average power. Since radar peak power tends to be
independent of pulse width, this single threshold value can be applied for
all pulse widths.
Limits: -60 dBm to +10 dBm
Design/Analysis Window– 0:Rect, 1:Hamming, 2:Blackman : 1
You may choose the window that is used in the design of the FIR matched
filter and the presentation of the power spectra for the various scope plots.
Choices are rectangular, Hamming, and Blackman; the Hamming window