# An Indoor DFEC Ranging Method for Homologous Base Station Based on GPS L1 and BeiDou B1 Signals
## 3 Implementations and Evaluation
### Wired Connection Test  
The connection of the wired test environment is shown in Figure 3. The channels of the transmitter are connected by RF cables of the same length and are combined to the receiver through the combiner signal. The right part of the figure below is the status of the information output by the ulox receiver. The information output by the data window includes pseudolite number, pseudorange, carrier phase, doppler and carrier-to-noise ratio and so on. The part of the bar graph is the carrier-to-noise ratio of the receiver output. A. Test Results of Switching Pseudolite Base Station  
In this section, we mainly analyze the influence of the switch on the signal. Each time the machine is turned on or off, the time-frequency characteristics of the transmitting base station, the signal characteristics of the baseband module and the radio-frequency module are more or less affected. Therefore, it is necessary to analyze the influence of the signal error introduced on the ranging estimation through the switch. Here, we give the data processing results after switching the pseudolite base station three times, including the intra-cycle phase difference between L1 frequency channels, the intra-cycle phase difference between B1 frequency channels, and the whole-cycle estimated distance between channels. It can be seen from the following Figure 4 that the phase difference between the channels of the L1 output after the power-on and turn-off is basically the same, and there is a phase error of \(\pm\) 0.005 \(\sim\pm\) 0.01 cycles. The phase difference between the channels of the B1 in the Figure 5 remains the same every time the machine is turned on and off, and there is a phase error of \(\pm\) 0.01 \(\sim\pm\) 0.02 cycles. From this we get the estimated value of the whole cycles of the distance difference in Figure 6. It can be seen from the figure that the count of whole cycles has an uncertainty of one cycle, that is, one cycle of ranging errors may be introduced. B. Cold Start Receiving Terminal Test  
In this section, we will mainly analyze the impact on the estimated count of the whole cycles from the receiving end. With each cold start, the receiver will reacquire the signal on the basis of no prior information, so each time the signal is allocated to the channel after the replenishment, it will also be randomly allocated. This experiment can verify the influence of channel consistency on the the estimated count of the whole cycles. Of course, it also includes the influence of the measurement error introduced by the receiving terminal itself. Figure 4: Test of influence of power on/off on L1 phase difference results between channels. Figure 3: Wired environment test chart. Figure 5: Test of influence of power on/off on B1 phase difference results between channels. Figure 6: The distance based on the phase difference is estimated by the whole number of wavelengths. Here we give the data processing results after three cold starts. Figure 7 shows the phase difference between the channels at the L1 frequency and Figure 8 shows the phase difference between the channels at the B1 frequency. It can be seen from the figure that the phase difference between the two signals output after the three cold starts is basically the same, and the phase difference error of the cycle at the L1 frequency is \(\pm\) 0.005 \(\sim\)\(\pm\) 0.01 cycle. The phase difference error of the cycle at the B1 frequency is \(\pm\) 0.005 \(\sim\)\(\pm\) 0.01 cycle. On this basis, we get the the whole cycles estimate of the distance difference between the channels, as shown in Figure 9. The whole cycles estimated distance difference between the channels is basically the same, but there is one wavelength estimation error.