Vaisala RVP900 User Manual

USER’S MANUAL__________________________________________________________________
320 _________________________________________________________________ M211322EN-D
7.18 Load Custom Range Normalization
(LDRNV)
Reflectivities computed by the RVP900 are ordinarily corrected for range
effects by adding an offset in deciBels equal to 20 log(R/1 km), where R is
the range in kilometers. This correction is based on a simple filled beam
geometry, and is sufficiently accurate for most meteorological
observations. The LDRNV command is provided for applications in which
an alternate custom range correction is required, for example, if the radar
receiver's LNA were to be driven by an external user-supplied STC
waveform.
LDRNV loads a 251-word custom correction table holding values in
hundredths of deciBels over five decades of log(range) from 0.01km to
1000km. There are 50 table entries per decade of range. Thus, the range in
kilometers corresponding to an input word #N is 10[{{N-1}<devide>50}-
2], and the default correction table (automatically used on power-up) is
simply 40(N - 101) . The table values are stored and interpolated whenever
the RVP900 loads a new range mask (see Section 7.2 Load Range Mask
(LRMSK) on page 257), at which point custom values for the actual user
ranges are computed. The LDRNV command need be issued only once,
but it must be done prior to choosing the working set of range bins.
The linear intervening gas attenuation correction (see Section 7.3 Setup
Operating Parameters (SOPRM) on page 259) is always added to the
reflectivity data, regardless of whether default or custom range
normalization is in effect. If this is undesirable, the intervening gas slope
should be set to zero.
0916-165
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| | 1 0 1 0 1 | Command
|___________________________________________|___________________|
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Signed Hundredths dB of Range Normalization for Range 0.01 km | Input 1
|_______________________________________________________________|
.
.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
| | | | | | | | | | | | | | | | |
| Signed Hundredths dB of Range Normalization for Range 1000 km | Input 251
|_______________________________________________________________|

Vaisala RVP900 Specifications

General

Brand	Vaisala
Model	RVP900
Category	Receiver
Language	English