User's Manual Part 2

Processing Algorithms (draft)
RVP8 User’s Manual
April 2003
5–59
HH + VV Channels
Processing is identical to Cases 2&3: STAR and Single Channel Alternating HH+VV
Processing.
HV + VH Processing
The weighting here has to correct for both transmitter and receiver effects in order to use the HH
channel dBZ
o
.
T
0
Ą +Ą
xdr
gdr
T
hv
o
) xdr
*1
ĄT
vh
o
2
R
0
Ą +Ą
xdr
gdr
R
hv
o
) xdr
*1
ĄR
vh
o
2
R
1
Ą +Ą
xdr
gdr
R
hv
1
) xdr
*1
ĄR
vh
1
2
R
2
Ą +Ą
xdr
gdr
R
hv
2
) xdr
*1
ĄR
vh
2
2
NĄ +Ą
xdr
gdr
N
h
) xdr
*1
ĄN
v
2
These adjusted autocorrelations are then used as input to the standard moment processing
algorithms with dBZo calibrated with respect to the HH channel.
An example of how this weighted averaging works is given here. Suppose that we want to
compute the average of the reflectivities for the VH and HV channels,
Z
hv)vh
+ Cr
2
S
hv
) S
vh
2
+ Cr
2
T
hv
0
*N
h
g
r
h
g
t
v
)
T
vh
o
*N
v
g
r
v
g
t
h
2
+
Cr
2
g
r
h
g
t
h
(T
hv
0
* N
h
)
g
t
h
g
t
v
) (T
vh
o
* N
v
)
g
r
h
g
r
v
2
but since xdr +
g
r
v
g
h
v
and gdr +
g
r
v
g
t
v
g
r
h
g
t
h
Z
vh)hv
+
Cr
2
g
r
h
g
t
h
ȧ
ȱ
Ȳ
xdr
gdr
T
hv
0
) xdr
*1
T
vh
0
2
*
xdr
gdr
N
h
) xdr
*1
N
v
2
ȧ
ȳ
ȴ
Z
vh)hv
+
Cr
2
g
r
h
g
t
h
ƪ
T
0
* N
ƫ
+
ƪ
Cr
2
o
N
h
g
r
h
g
t
h
ƫ
ƪ
r
2
r
2
o
ƫƪ
T
0
* N
N
h
ƫ
The first term in brackets is precisely dBZ
o
for the HH channel. Thus if we average the
correlations using the appropriate GDR and xdr weighting as shown above, then the average
reflectivity is obtained by using conventional processing with the HH channel dBZ
o.