GPS卫星信号 – L1&L2载波
L1 Carrier 1.57542 GHz
C/A Code 1.023 MHz
Navigation Data 50 Hz
P Code 10.23 MHz
L2 Carrier 1.2276 GHz
L1 Signal
L2 Signal
modulo 2 adder
modulator
+
+
+
+
+
+
+
Denotes option 409 and N7609B multi-satellite signal
Σ
90˚
Page 8
GPS 卫星信号－导航电文
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
1
TLM
2
HOW
3 4 5 6 7 8 9 1
0
1
TLM
2
HOW
3 4 5 6 7 8 9 1
0
1
TLM
2
HOW
3 4 5 6 7 8 9 1
0
1
TLM
2
HOW
3 4 5 6 7 8 9 1
0
1
TLM
2
HOW
3 4 5 6 7 8 9 1
0
Satellilte
clock and
health data
Ephemeris
Ephemeris
Partial
almanac &
other data
Almanac
8 bits
preamble
16 bits
reserved
6 bits
parity
7 bits
ID
17 bits
Time of week
TOW
6 bits
parity
Navigation message
25 pages/frames
37500 bits
12.5 minutes
Frame (page)
1500 bits
30 seconds
Telemetry word (TLM)
30 bits
0.6 seconds
Handover word (HOW)
30 bits
0.6 seconds
Sub-frame 2
300 bits
6 seconds
Sub-frame 1
Sub-frame 3 Sub-frame 4 Sub-frame 5
定义: 每秒50位连续的数据流
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