Global Positioning System Reference
In-Depth Information
18.
Find the bits representing the
Z
-count and determine the time of week in
days, hours, minutes, and seconds.
Hint: Look in the GPS Interface Control Document (icd200c.pdf) on page 65+
for a complete description of navigation data contents. Check if the sequence is
inverted compared to the result of Problem 17.
19.
We load the data file
data_long2.mat
.This
M
-file contains data collected
from a local antenna and the sampling frequency is 38
.
192 MHz. Compute a po-
sition based on the data in the
M
-file.
Hints:
-
make acquisition on the first ms of data,
-
track all the available satellites,
-
decode the navigation messages on all the satellites,
-
compute pseudoranges to all the available satellites,
-
compute the satellite positions at transmit time,
-
compute the position based on the pseudoranges and the satellite positions.
40
◦
N
277
◦
E
20.
Given a point with
(ϕ, λ,
h
)
=
(
,
,
231 m
)
in WGS 84, find the
Cartesian coordinates
(
X
,
Y
,
Z
)
. Hint: Use
geo2cart
.
21.
from Problem 20, find the geographical
coordinates of the point in WGS 84. Hint: Use
cart2geo
.
Given a point with the
(
X
,
Y
,
Z
)
22.
Given
X
=
3
,
429
,
122
.
662,
Y
=
604
,
646
.
845, and
Z
=
5
,
325
,
950
.
420,
convert
(
X
,
Y
,
Z
)
into
(
N
,
E
)
in UTM, zone 32. Hint: Use
cart2utm
.
23.
Convert
N
=
6
,
318
,
036
.
28,
E
=
560
,
828
.
13 into geographical coordinates
(ϕ, λ)
. Hint: Use
utm2geo
.
57
◦
N,
10
◦
Einto
24.
Convert
ϕ
=
λ
=
(
N
,
E
)
in UTM, zone 32. Hint: Use
geo2utm
.
25.
Convert the UTM coordinates
N
=
6
,
317
,
972
.
081,
E
=
560
,
749
.
622 into
geographical coordinates. Hint: Use
utm2geo
.
26.
Compute GDOP for a constellation of four satellites:
-
one at zenith and three equally spread along the horizon;
-
consider a constellation of four satellites equally spread at an elevation an-
gle of 45
◦
.
27.
Convert the epoch 8h on 29 March 2005 to Modified Julian Date and GPS
weeks and seconds of week. Hint: Use
julday
and
gps_time
.
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