Global Positioning System Reference
In-Depth Information
TABLE 5.10 Ephemeris Parameters in Subframe 3
Number
of
Bits
Scale
Factor
(LSB)
Effective
Range
Parameter
Location
Units
16
∗
2
−
29
C
ic
: Amplitude of the
cosine harmonic
correction term to
angle of inclination
61-76
radians
32
∗
2
−
31
e
: Longitude of
ascending node of
orbit plane at
weekly epoch
77 - 84; 91 - 114
semicircles
16
∗
2
−
29
C
is
: Amplitude of the
sine harmonic
correction term to
angle of inclination
121 - 136
radians
32
∗
2
−
31
i
0
: Inclination angle
at reference time
137 - 144; 151 - 174
semicircles
16
∗
2
−
5
C
rc
: Amplitude of the
sine harmonic
correction term to
the orbit radius
181 - 196
meters
32
∗
2
31
ω
: Argument of
perigee
197 - 204; 211 - 234
semicircles
˙
: Rate of right
ascension
24
∗
2
−
43
241 - 264
semicircles/sec
IDOE
271 - 278
(see text)
14
∗
2
−
43
idot: Rate of
inclination angle
279 - 292
semicircles/sec
5.14 NAVIGATION DATA FROM SUBFRAMES
4 AND 5-SUPPORT DATA
(
3,7,8
)
Both subframes 4 and 5 are subcommutated 25 times each. The 25 versions
of these subframes are referred to as pages 1 to 25 of each superframe. With
the possible exception of “spare” pages and explicit repeats, each page contains
different data in words 3 through 10, which are from bits 91 - 300. Subframe 4
has six different formats but only five of them are shown in Figure 5.10a. Five
pages, 1, 6, 11, 16, 21, are in one format. Six pages, 12, 19, 20, 22, 23, 24, are
in one format. Page 18 is in one format. Page 25 is in one format, and pages
13, 14, 15, and 17 are in one format. There are a total of 17 pages. Pages 2, 3,
4, 5, 7, 8, 9, and 10 are not shown because they have the same format as page
1 through 24 of subframe 5. Subframe 5 has two different formats as shown in
Figure 5.10b.
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