# A Fast Acquisition Algorithm for Hybrid Signals of 5G and BeiDou B1
## 3 Results and Discussion
### Receiver Hybrid Coherent Acquisition Performance Analysis  
In this paper, we conducted practical tests on BeiDou B1 and 5G signals and statistically analyzed the resulting data. One of the test objectives is to derive the performance of the navigation receiver during regular use and to calculate the acquisition performance of B1I and B1C at this time, including the acquisition time, acquisition accuracy, and peak value of acquisition-related operations. The RF center frequency point of the signal is 1561.098 MHz, the nominal center of B1I, the instantaneous bandwidth is 80 MHz, and the sampling rate is the same as the sampling rate of 200 MHz in the previous algorithm analysis when the actual measurement is acquired. The acquired signal contains all the navigation signals within this frequency band, including BeiDou B1I, B1C, GPS L1/CA, and Galileo. Since the acquisition location is far from an urban area, we can guarantee that the acquired signals contain only navigation signals, noise, and no other interference. At the same time, because there is no obstruction from buildings, the number of visible satellites in the collected signals is high, and enough satellite signals can be captured. The SC-PMF-FFT algorithm enhances the acquisition sensitivity by affecting the search field evaluation and detection judgments in different parameter configurations. The actual parameters are selected considering both the real alarm rate and false alarm rate requirements and the integration length. Suppose the selected number of parallel correlator values needs to be more significant. In that case, the acquired signal that has just crossed the threshold will likely be loop-locked in the subsequent tracking, so the number of parallel correlator values can be increased to meet the theoretical requirements. The SC-PMF-FFT algorithm parameter configuration is shown in Table 12.  
In the above parameter configuration, higher sensitivity can be obtained by using a more significant number of block accumulations, coherent integration times, and incoherent integration times. The test results are shown in Figures 11 and 12. In the test environment of this paper, due to the small relative speed between the terminal and the source, the residual carrier frequency of the baseband signal during the acquisition of the terminal in regular use is mainly caused by the deviation of the crystal oscillator. Such hardware-induced residual carrier frequencies are usually minor, so the positioning signal's center frequency is adjusted to more comprehensively test the frequency acquisition accuracy of the terminal for different frequencies. Different integration settings, block accumulation, and FFT length lead to different frequency acquisition accuracies, where we set the deviation of the source frequency from the original center frequency by 300 Hz, 600 Hz, and 900 Hz, respectively. Five hundred acquisitions and tracks are performed for each deviation, and the acquisition deviations are obtained by comparing the frequency acquisition results with the results after stable tracking. The captured deviations are obtained by comparing the frequency capture results with the stable tracking results. The SC-PMF-FFT method has the highest frequency capture accuracy with this parameter setting.