# An In-Depth Assessment of the New BDS-3 B1C and B2a Signals
## 4 Carrier-To-Noise Density Ratio
### C/N\({}_{0}\) Statistical Characteristics of MEO Satellites  
BDS-3 has a large number of MEO satellites and is the main component of the BDS-3 space segment. The MEO constellation of BDS-3 uses a total of 27 satellites in the three orbital planes A, B, and C. In order to study the difference in C/N\({}_{0}\) between BDS-3 and BDS-2 satellites on different frequencies, all MEO satellites were analyzed and evaluated. Because the elevation of MEO satellites varies widely, and the elevation trajectories between different satellites are extremely different. C14 (BDS-2) and C24 (BDS-3) have similar elevation ranges, so they are put together for comparison. Figure 5 shows the analysis results of the two satellites. It can be found that the C/N\({}_{0}\) values are closely related to the elevation. On the B1 frequency, the C/N\({}_{0}\) value of the C24 satellite of BDS-3 is significantly higher than that of C14, while at frequency B3, the C/N\({}_{0}\) value of C14 is slightly higher than that of the C24 satellite. The strength of the B2a signal of the C24 is significantly higher than other frequencies. The C/N\({}_{0}\) of all MEO satellites are analyzed (including 3 BDS-2 satellites and 24 BDS-3 satellites), and the results are shown in Table 4. Because there are fewer BDS-2 satellites, the average elevation on the day of the experiment is 32.41 degrees, which is much lower than the BDS-3 satellite elevation of 39.33 degrees. On the B1I frequency, the MEO satellites of BDS-3 have a significant improvement over BDS-2, while on the B3I frequency, they are \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**System**} & \multirow{2}{*}{**Satellite**} & \multirow{2}{*}{**Elevation** **(Average)**} & \multirow{2}{*}{**B1I**} & \multirow{2}{*}{**B1C**} & \multirow{2}{*}{**B2a**} & \multirow{2}{*}{**B2I**} & \multirow{2}{*}{**B3I**} \\  & & & & & & & \\ \hline \multirow{8}{*}{**BDS-2**} & average & 54.67 & 43.35 & & & 43.76 & 46.08 \\  & C06 & 55.09 & 42.81 & & & 43.99 & 45.87 \\  & C07 & 55.41 & 43.37 & & & 44.39 & 46.60 \\  & C08 & 54.51 & 42.81 & & & 44.22 & 46.63 \\  & C09 & 54.37 & 42.88 & & & 43.54 & 46.55 \\  & C10 & 54.54 & 42.59 & & & 43.36 & 45.78 \\  & C13 & 53.50 & 44.38 & & & 43.89 & 45.26 \\  & C16 & 55.24 & 44.58 & & & 42.95 & 45.86 \\  & average & 54.88 & 45.36 & 45.76 & 49.31 & & 46.18 \\  & C38 & 55.07 & 45.36 & 46.04 & 49.43 & & 46.13 \\  & C39 & 55.17 & 45.45 & 45.57 & 49.25 & & 46.24 \\  & C40 & 54.40 & 45.28 & 45.67 & 49.26 & & 46.18 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Statistics of all inclined geosynchronous satellite orbit (IGSO) satellites. Figure 5: C/N\({}_{0}\) values of some medium earth orbit (MEO) satellites on different frequencies. equivalent. For the new signal of the BDS-3 MEO satellites, B1C is higher than B1I but lower than B3I, while B2a is significantly higher than other frequencies. \(\rm C/N_{0}\) of different types of BDS satellites are shown in Table 5, including all BDS-2 and BDS-3. The \(\rm C/N_{0}\) of the BDS-3 satellites on B1I frequency is significantly higher than that of the BDS-2 satellites, and they are equivalent at the B3I frequency. The new B1C and B2a signals have been broadcast on IGSO and MEO satellites of BDS-3. The \(\rm C/N_{0}\) value of the B2a signal is nearly 3 \(\rm dB/Hz\) higher than other frequencies (as shown in Figure 6).