To generate the BPSK(1) and BOC(1,1) signals in software receiver, the GNSS IF signal generator developed by CSLab in Chungnam National University has been used. The power spectral density of generated GPS L1 C/A signal is shown in Figure 4. The generated GPS L1 C/A signal includes C/A code and navigation data messages. All available PRN number can be included in this signal and the navigation data derived from real receiver or a GPS simulator is applied to generate navigation message.

Figure 5 shows a block diagram of tiered signal generation for Galileo E1 signal. At that figure, f_c and f_cs mean the primary and secondary code chip-rate respectively, and the relation, f_cs = f_c / N, is satisfied. The detail description for this signal can be found in Table 1 [3].

The power spectrum of generated Galileo E1 signal is shown in Figure 6. It includes ranging code such as primary code and secondary code, and subcarrier for BOC(1,1) modulation. 50 primary codes in the Galileo OS SIS ICD (Open Service Signal In Space Interface Control Document) are applicable to this signal, same as secondary code.

Due to the conceptual similarity of Galileo and GPS, the high-level architecture of Galileo receiver is similar to that of GPS receivers. The essential new element of the new GPS/Galileo receivers is a generic channel, which is able of tracking all the possible modulation schemes including GPS C/A, L2C and Galileo BOC(1,1). The baseband chipset of future GNSS receivers will represent a matrix of generic channels. Future receivers built based on this concept, shall use flexible allocation schemes of channels to incoming signals.

The block diagram of the generic channel is presented in Figure 7 [4]. One of the main differences between the current C/Acode signal and the Galileo signals is the presence of a data-less pilot signals in parallel with the data-bearing signal. With the channel architecture shown in Figure 7 both the pilot and data components can be demodulated in parallel.