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The variation in the pseudorange obtained by the receiver discussed in Section 38.5.2 is compared to the variation in the true range between a mobile receiver and cellular CDMA BTSs. For this purpose, the receiver was mounted on two platforms: (i) an unmanned aerial vehicle (UAV) and (ii) a ground vehicle [12, 18, 25].

UAV Results: Figure 38.20 shows the BTS environment, the UAV trajectory, and the experimental hardware setup. Signals from two cellular BTSs corresponding to the US cellular provider Verizon Wireless were tracked. The BTSs transmitted at a carrier frequency of 883.98 MHz and their positions were mapped prior to the experiment [37, 39]. The ground‐truth reference for the UAV trajectory shown in Figure 38.20 was taken from its onboard navigation system, which uses GPS, an INS, and other sensors. The distance D between the UAV and each BTS was calculated using the navigation solution produced by the UAV’s navigation system and the known BTS position. The pseudorange ρ was obtained from the cellular CDMA receiver that was mounted on the UAV. In order to validate the resulting pseudoranges, the variation of the pseudorange Δρ ≜ ρ − ρ(0) and the variation in distance ΔD ≜ D − D(0) are plotted in Figure 38.21 for the two BTSs, where ρ(0) is the initial value of the pseudorange, and D(0) is the initial distance between the UAV and the BTS. It can be seen from Figure 38.21 that the variations in the pseudoranges closely follow the variations in distances. The difference between ΔD and Δρ for a particular BTS is due to the variation in the clock bias difference and the noise v_i.

Figure 38.20 BTS environment and experimental hardware setup for the UAV experiment. Map data: Google Earth (Khalife et al. [12]).

Source: Reproduced with permission of IEEE.

Figure 38.21 Variation in pseudoranges and the variation in distances between the receiver and two cellular CDMA BTSs for the UAV experiment (Khalife et al. [12]).

Source: Reproduced with permission of IEEE.

Ground Vehicle Results: Figure 38.22 shows the BTS environment, ground vehicle trajectory, and the experimental hardware setup. Signals from two cellular BTSs corresponding to the US cellular provider Verizon Wireless were tracked. The BTSs transmitted at a carrier frequency of 882.75 MHz, and their positions were mapped prior to the experiment [37, 39]. The ground‐truth reference for the ground vehicle trajectory in Figure 38.22 was obtained from the Generalized Radionavigation Interfusion Device (GRID) GPS SDR [58]. The change in the true range and the change in pseudorange are plotted in Figure 38.23, similarly to the UAV experiment. It can be seen from Figure 38.23 that the variations in the pseudoranges closely follow the variations in distances. The difference between ΔD and Δρ for a particular BTS is due to the variation in the clock bias difference and the noise v_i.