The following table shows the modes available in the command word.
Table 67 PROC Modes
Mode Description
Synchronous
mode
The processor acquires, processes, and outputs one ray in response to each PROC
command.
Processing begins after each command is received.
Free running
mode
A single PROC command is issued, and rays are continually output as fast as they can be
produced and consumed.
This continues until any other command is written, for example, a NOP can be used to
terminate the free running mode with no other consequences.
Time Series
mode
The processor acquires, processes, and outputs one ray of time series samples in response
to each PROC command.
Data are output as 8-bit time series, 16-bit time series, or 16-bit power spectra.
Optional Dual-PRF velocity unfolding is chosen by command bits 8 and 9. For Doppler data
either a 2:3, 3:4, or 4:5 PRF unfolding ratio may be selected. RVP900 performs the unfolding
steps internally, so mean velocity is output with respect to the larger unambiguous interval.
No additional velocity processing is needed except to change the velocity scale on any
generated displays.
Spectral widths are scaled consistently with respect to the higher PRF, and require no user
modification before being plotted.
When unfolding is selected, the internal trigger generator automatically switches rates on
alternate rays. The switch over occurs immediately after the last pulse of the current ray has
been acquired; thus overlapping the internal post-processing and output time, with
transmitter stabilization and data acquisition at the new rate.
Output data are selected by the upper 6 bits of the PROC command. Packed archive output
is selected by setting the ARC bit. Individual byte or word display output is selected by
setting any or all of the Z, T, V, W, Zdr, and Kdp command word bits. When more than one
of these bits is set, the output array consists of all of the bins for the leftmost selected
parameter, followed by all of the bins for the next selected parameter, and so on. Bits
selected in XARG #1 behave the same way, except that the output order is right-to-left.
Both archive and display formats can be selected simultaneously, in which case the archive
format is output
first, followed by whichever individual display format values were also
selected. The archive format is not recommended for use with new drivers, because it can
only handle four of the many possible output parameter types.
In time series mode, there are three output data formats available. For backwards
compatibility, there is an 8-bit integer format, in which the 8 most
significant bits from the I,
Q, and LOG signals are represented in a byte. This format is not recommended, because it
generally misses weak signals. Vaisala recommends the
floating-point format that uses 16-
bits per A/D sample. There is also a 16-bit power spectrum output that is accurate to 0.01 dB
(see also GPARM output word #10).
In addition to the above output data, the
first words of each ray optionally contain
additional information about the ray. These header words are configured by the CFGHDR
opcode, and are included only if the NHD (No-Headers) bit in SOPRM Input #2 is clear.
RVP900 User Guide M211322EN-J
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