ABSTRACT
As of the time of writing this chapter, Global Positioning System (GPS) satellites transmit signals at two frequencies, designated as L1 and L2, on which three binary modulations are impressed: the C/A-code, the P(Y)-code, and the broadcast (or navigation) message, as depicted in Figure 8.1. L1 is the principal GPS carrier signal with a frequency of 1575.42 MHz, and is modulated with the P(Y)-code, the C/A-code, and the navigation message. The second signal, L2, is transmitted at a frequency of 1227.60 MHz and in the case of the Block IIA/IIR series of satellites is modulated
8.1 GPS Signal Characteristics ........................................................................... 115 8.1.1 Signal Structure ................................................................................ 115 8.1.2 Signal Coverage ................................................................................ 118
8.2 Codes and Pseudorange Measurements ........................................................ 119 8.2.1 Pseudorandom Noise Codes ............................................................. 119 8.2.2 Determining Satellite-Receiver Range ............................................. 120
8.3 Navigation Message ...................................................................................... 121 8.3.1 Broadcast Ephemeris ........................................................................ 121 8.3.2 Broadcast Satellite Clock Error Model ............................................. 122
8.4 Carrier Waves and Carrier Phase Measurements .......................................... 122 8.4.1 Ambiguous Carrier Phase ................................................................. 123 8.4.2 Unambiguous Carrier-Range ............................................................124
