Global Positioning System Reference
In-Depth Information
15
1.5
10
5
1
0
1
−
5
0.5
−
15
−
0
−
1
−
0.5
0
0.5
1
0
200
400
600
800
1000
Delay (microseconds)
Early-late spacing (microseconds)
15
1.5
10
5
1
0
5
1
−
0.5
−
15
−
0
1
0.5
0
0.5
1
0
200
400
600
800
1000
−
−
Delay (microseconds)
Early-late spacing (microseconds)
15
1.5
10
5
1
0
1
−
5
0.5
−
−
15
0
−
1
−
0.5
0
0.5
1
0
200
400
600
800
1000
Delay (microseconds)
Early-late spacing (microseconds)
15
1.5
10
5
1
0
1
−
5
0.5
−
15
0
−
0
0.5
1
0
200
400
600
800
1000
−
1
−
0.5
Delay (microseconds)
Early-late spacing (microseconds)
Figure 6.11
Effects of one-path multipath on pseudorange estimation, BPSK-R(1) modulation strictly
bandlimited to 24 MHz. Top row shows no multipath, while in subsequent rows MDR is -10 dB and excess
delay is 0.1
µ
s, while phase is 0º, 90º, and 180º. Left-hand column shows distorted correlation functions,
while right-hand column shows dependence of range error on early-late spacing.
To assess the effect of one-path multipath on carrier phase estimation, consider
further the composite correlation function obtained in (6.46) resulting from
one-path multipath,
~
~
~
~
−
j
φ
R
(
ττ
−=
)
R
(
ττ
−+
)
α
e
R
(
ττ
−−
τ
)
. It has real part
1
x
0
x
0
1
x
0
1
cos
~
sin
~
~
~
~
~
R
(
ττ
−+
)
α
φ
R
(
ττ
−−
τ
)
and imaginary part
αφτ
R
x
(
−−
τ
τ
)
.
x
0
1
1
x
0
1
1
1
0
1
The phase angle is given by
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