Global Positioning System Reference
In-Depth Information
Correlation peak
1023
y
p
Final y
e
y
l
Initial y
e
d
d
−
1
x/2
1
Time
FIGURE 11.10
Variation of peak correlation outputs.
Portion of correlation triangle
y
esa
Final output
Initial output
20 ms
Time
FIGURE 11.11
Detailed changes of
y
e
per ms.
ending points, or the mean of the 20
y
e
outputs. Since the reference signals used
to generate
y
e
,
y
p
,and
y
l
contains the C/A code and the carrier frequency, the
summation of the results can be considered coherent processing, and the results
are labeled
y
es
,
y
ps
,and
y
ls
. If the carrier frequency is exactly right,
y
e
,
y
p
,and
y
l
should be added in phase and achieve the maximum value. Otherwise, the
results might be slightly off. The amplitudes of three quantities,
y
es
,
y
ps
,and
y
ls
,
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