## 3 Results  
The proposed dual-component universal channel ends up using twice the resources of a traditional GPS L1 C/A tracking channel, in exchange for the flexibility of tracking any GNSS signal (including both pilot and data, whenever applicable). Furthermore, it has a low worst-case 42 mW/channel dynamic power consumption. This corresponds to a 66% increase compared to the reference BPSK single-component channel. Keeping in mind that a FPGA, such as the one used in the current implementation, reaches consumption as much as 12 times that of a comparable size Application Specific Integrated Circuit (ASIC) [46], an equivalent ASIC implementation power consumption would 3.5 mW/channel, or 2.1 mW/channel for the simplest BPSK implementation. These values are comparable to the consumption of the u-blox GPS L1 C/A with SBAS receiver chip specified to be 67 mW for 50 channels (1.34 mW/channel) [47]. Furthermore, the current processing bottleneck is the discriminators computation through the 1 kHz interrupt sub-routine/channel in the embedded MicroBlaze 5.0 processor, which could be resolved with a newer, more powerful, chip. Alternatively, the navigation message decoding could be performed in an external processor. Note that in all cases, except for GPS L2C, a 10 non- coherent integrations of 1 ms is performed prior to computing the DLL feedback. The resulting commands lead to a trend represented in Figure 10, where Low Significant Bit (LSB) oscillations may be observed between commands reaching up to 0.06 \(\times\) 10\({}^{-9}\) s/ms. These equivalent 18 m/ms jumps are smoothed out in the PVT solution, computed at up to 100 Hz. Another performance assessment is the instantaneous channel update mean time of 1.07 ms, allowing the receiver to rapidly adapt to its sensed environment. Finally, the 530+ civil signal components occupy a total memory codes size of ~5 MB (exception made of the L2 CL code). Hence, pre-computed spreading codes may easily be stored in external memory and used on demand. Figure 10: GPS L1 C/A LoS Variation (s) Observed every 1 ms Epoch, Based on 10 ms Non-Coherent Integration Time DLL Feedback Commands. A metric to consider when seeking for the best signals to track is their pseudo-range noise. The pseudo-range being proportional to the propagation time (_cf._ Equation (21)), it should behave approximately as a parabola for a static observer, from horizon to zenith and horizon again. Its second derivative should thus tend towards a constant value. The DLL feedback can be approximated as the first derivative of the propagation time (_cf._ Equation (22)), as shown in Figure 10.  
The pseudo-range noise--a random process with an order greater than 2--may then be approximated as the remaining variations of the second derivative of the pseudo-range (_cf._ Equation (23)) [48], which is generalized to a partial code within 1 ms (in Equation (24)) for the particular case for L2C (outlined in Equation (25)). At that level, only the chip index and the phase of the chipping rate clock signal, taken at 1 kHz, need to be considered ([49] (p. 264). This simplification is useful in analyzing signals, as the associated navigation message does not need to be accounted for. Moreover, multi-frequency signals being characterized by different paths, the extra time offset may then be neglected [50].