The navigation information is modulated on the L1 carrier and its signal frequency is 50 Hz. It contains the GPS satellite orbital parameters, satellite clock corrections and other system parameters. The user generally needs to use this navigation information to calculate the position of the GPS satellite in the earth orbit at a certain time, and the navigation information is also called broadcast ephemeris.
SPS and PPS are GPS systems that provide two different types of services for different users. One is the SPS Standard Positioning Service and the other is the PPSP Precision Positioning Service. These two different types of services are provided by two different subsystems. The standard positioning service is provided by the SPS Standard Positioning System and the precision positioning service is provided by the PPSP Precision Positioning System.
SPS is mainly for civil users around the world.
PPS is mainly aimed at the military departments of the United States and its allies and civilian licensed users.
In GPS positioning, one or more of the following observations are often used for data processing to determine the coordinates of the point to be fixed or the baseline vector between the points to be determined:
L1 carrier phase observations
L2 carrier phase observations (half-wave or full-wave)
Modulate the C/A code pseudorange on L1
Modulate P code pseudorange on L1
Modulate P code pseudorange on L2
Doppler shift on L1
Doppler shift on L2
In fact, when performing GPS positioning, in addition to using the above observations in large numbers for data processing, some special observations formed by certain combinations of the above observations, such as wide-lane observations (Wide- Lane), Narrow-Lane observations, Ion-Free observations (Ion-Free) are used for data processing.