Vaisala RVP900

Chapter 7 __________________________________________________ Host Computer Commands
VAISALA______________________________________________________________________ 339
The input data are the maps of melting layer altitudes projected into sweep
cones of the data sweeps, to be carried out by OpCommand PROC.
The command is an extended OP command and is defined as follows:
The lowest 5 bits correspond to the default 0X1F for extended OP
commands and the 7 middle bits are the actual value for the
XOP_MLSPEC command (0X10).
The application SW provides the input data, for example by converting the
IRIS standard Cartesian MLHGT products into the curved Earth co-
ordinates of the sweeps configured for the radar task. Typically, a map for
a collection of sweeps (a volume) is uploaded.
Application SW adjusts the spatial resolution of the map by down scaling
of gates so that it fits in the buffer managed in RDA:
DPOLAPP_MAX_ML_SWEEPS*DPOLAPP_MAX_ML_RAYS*DPO
LAPP_MAX_ML_BINS
The command also checks the maximum number of sweeps and rays
(DPOLAPP_MAX_ML_SWEEPS = 30 and
DPOLAPP_MAX_ML_RAYS=90). If the buffer does not exist or exceeds
its limits, it is flushed.
The RVP900 supports command that provides a mean to feedback the
melting layer information from IRIS into the RDA. So that, the melting
layer altitude information is specified for every antenna angle as well as
range. This way melting layer height can be used in different live data
processing applications such as Hydroclass.
The RVP900 maintains an internal array of up to 1024 different filter
versus- range tables, each of which is keyed to a particular angle (EL, for
PPIs and AZ, for RHIs). Each XOP_MLSPEC command uploads the
complete sweep. Then, for each live bin in every ray being processed, the
RVP900 obtains the melting layer at the midpoint AZ/EL of the ray.