Global Positioning System Reference
In-Depth Information
Fig. 12. Joint data/pilot acquisition architectures: (a) Dual Channels - DC; (b) (B
C); (c)
Assisted (B-C); (d) Summing Combination - SuC; (e) Comparing Combination - CC
×
6.1 Joint data/pilot acquisition strategies
The correlation process performs on both channels to produce
R
B
,
m
and
R
C
,
m
(5). After that,
these correlation values are combined as follows:
•
Dual Channel (DC):
This strategy sums the square envelopes from the two channels, see Fig. 12(a). The decision
variable is
M
m
=
1
(
|
R
B
,
m
|
M
m
=
1
(
|
S
B
,
m
|
2
2
2
2
S
DC
K
=
+
|
R
C
,
m
|
)=
+
|
S
C
,
m
|
)
(50)
×
•(B
C):
In this strategy [see Fig. 12(b)], the decision variable is
M
i
=
1
|{
R
B
,
i
·
R
C
,
i
}|
2
=
S
(51)
(
B
×
C
)
M
This strategy can be seen as another realization of the conventional differential technique
presented in Section 3.2.3. The correlator output in a channel is combined with the one
from the other channel instead of the delayed copy of itself as in the conventional differential
technique.
•
Assisted (B-C):
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