Viavi 87339, Operation Manual

Page: 147 / 198

Principals of Operation
6 -30
Table 6-3 Galileo Signals
6.1.9.C GPS Receivers
Signal
The strength of the received GPS signal relies on the following parameters:
•
Signal strength of satellite
•
Attenuation in transmitter hardware
•
Gain of transmission antenna (in direction to the receiver)
•
Free space loss due to distance of satellite and receiver
•
Attenuation by the atmosphere (negligible)
•
Deflection and superposition of the direct signal by reflected indirect signals
(multi-path)
• Gain of receiver antenna
• Attenuation in receiver hardware
• Signal tracking technique
Noise
The level of noise seen by a GPS receiver consists mainly of thermal noise but also
background and inter-modulation noise. Most of the single influences are constant or can
be assumed to be constant in the order of measurement accuracy.
Signal E5 (E5a + E5b) E1
Centre
Frequency
1191.795 (E5) 1575.42
1176.45 (E5a) 1207.14
(E5b)
Nominal
Bandwidth
51.15 (E5) 24.552
20.46 (E5a) 20.46 (E5b)
Modulation ALTBOC INTERPLEX/CBOC
Sub-carrier a-I a-Q b-I b-Q A B C
Sub-modulation None None None None BOC(15,2
.5)
CBOC(6,1
,1)
CBOC(6,1
,1)
Services F/NA
V
(OS)
Pilot I/NAV
(OS/CS/SoL
)
Pilot G/NAV
(PRS)
I/NAV
(OS/CS/S
oL)
Pilot
Code Rate
(Mc/s)
10.2
3
10.2
3
10.23 10.2
3
2.5575 1.023 1.023
Encrypted No No No No Yes No No
Sequence
Length (primary
x secondary)
1023
0 x
20
1023
0 x
100
10230 x 4 1023
0 x
100
25575 x 1 4092 x 1 4092 x 25
Symbol rate
(sps)
50 N/A 250 N/A 100 250 N/A