Global Navigation Satellite Systems Report of a Joint Workshop of the National Academy of Engineering and the Chinese Academy of Engineering (2012) / Chapter Skim
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Research Report on GNSS Interoperability--Lu Xiaochun, Lu Jun, Bai Yan, Han Tao, and Wang Xue
Research Report on GNSS Interoperability--Lu Xiaochun, Lu Jun, Bai Yan, Han Tao, and Wang Xue
Pages 35-74
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From page 35... ...
INTEROPERABILITY DEFINITION PARSING Elements of interoperability include coordinate reference frame, time reference frame, open signal, and the constellation. The resources probably applied in interoperability are global navigation satellite systems and their services, regional navigation satellite systems and their services, and augmentation sys tems and their services.
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+BOC(1,1) Open TABLE 2 Signal of Current GPS and Future GPS Center Code frequency rate Phase Signal (MHz)
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, 3 inclined geosynchronous orbit (IGSO) satellites, and 4 medium Earth orbit (MEO)
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38 FIGURE 1 Constellation of GPS and BeiDou regional system. Lu_Fig1.eps bitmap, landscape
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FIGURE 2 Constellation of GPS and BeiDou global system. Lu_Fig2.eps 39 bitmap, landscape
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-I -65 -70 -75 PSD -80 -85 -90 -95 -100 1.555 1.56 1.565 1.57 1.575 1.58 1.585 frequency (Hz) 9 x 10 FIGURE 4 Frequency spectrum in interoperability phase 1.
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Lu_Fig6.eps bitmap
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; reference signal SRe f is the copy of ideally base band signal from receiver; integral time Tp corresponds to the main period of reference signal. The correlation peak is correlated to ranging accuracy, anti-multipath, and anti-jamming of a signal.
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The bilateral power spectrum of interference signal baseband equivalent w(t) is twice the unilateral power spectrum of radio interference; power (Ps)
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10^6) Space of power spectrum Integral time Loop bandwidth Correlator space frequency Figure 8 shows that BPSK(2)
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. TABLE 5 Simulation Parameters a1 = -5 dB B = 30 MHz d = 1/20 code Extent ratio from multipath signal to firsthand signal Front receive Correlator space bandwidth
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. Lu_Fig9.eps bitmap FIGURE 10 Mean multipath error of BPSK(1)
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The colors in these figures represent the maximum correlation values. -15 5 10 -20 GPS Code 15 20 -25 25 30 -30 5 10 15 20 25 30 GPS Code FIGURE 11 Cross-correlation of GPS ranging code.
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Space signal accuracy includes user range error (URE) , user range ratio error (URRE)
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In a given system, with the same URE and same UEE, the positioning accuracy is determined by PDOP. Availability Service availability is the time ratio of congruous threshold value of position ing, timing, and velocity measurement in a prescriptive time period (usually a recursive period)
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TABLE 6 PDOP Value of GPS+BeiDou Regional System 50 Place GPS BeiDou GPS+BeiDou Place GPS BeiDou GPS+BeiDou Mean 1.697 2.360 1.224 1.666 2.422 1.193 Max Lintong 2.605 3.162 1.689 Beijing 2.662 3.250 1.683 Min 1.297 1.537 0.973 1.205 1.551 0.944 Mean 1.786 5.036 1.376 1.633 2.153 1.142 Max Kashi 5.660 12.611 2.055 Sanya 2.555 2.809 1.602 Min 1.243 1.943 1.045 1.108 1.460 0.833 Mean 1.619 3.528 1.189 1.646 3.445 1.245 Max Mohe 2.493 5.522 1.524 Tokyo 2.455 5.315 1.746 Min 1.202 1.873 0.919 1.251 1.733 1.014 Mean 1.522 2.107 1.085 Max Singapore 2.018 2.748 1.295 Min 1.253 1.447 0.905
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TABLE 7 TDOP Value of GPS+BeiDou Regional System Place GPS BeiDou GPS+BeiDou Place GPS BeiDou GPS+BeiDou Mean 0.884 1.433 0.661 0.865 1.481 0.630 Max Lintong 1.643 1.965 1.084 Beijing 1.635 2.049 1.057 Min 0.518 0.788 0.451 0.494 0.717 0.449 Mean 0.918 3.465 0.721 0.824 1.353 0.622 Kashi Sanya Max 3.714 8.690 1.361 1.446 1.855 0.969 Min 0.526 0.875 0.481 0.465 0.790 0.409 Mean 0.806 2.458 0.589 0.847 2.435 0.676 Mohe Tokyo Max 1.574 4.369 0.824 1.479 4.123 1.052 Min 0.506 0.834 0.409 0.577 0.887 0.493 Mean 0.721 1.318 0.579 Singapore Max 1.064 1.786 0.767 Min 0.534 0.813 0.460 51
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. Lu_Fig14.eps bitmap FIGURE 15 Average PDOP reducing in China (compare with BeiDou)
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. Lu_Fig16.eps bitmap FIGURE 17 Average TDOP reducing in China (compare with BeiDou)
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Calculate PDOP, TDOP of interoperability constellation, GPS constellation, and BeiDou constellation in seven days (a return period) point by point both in the region of United States.
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. Lu_Fig19.eps bitmap In the United States, the average PDOP reducing from interoperability constellation to GPS is 7.26 percent, and the average TDOP reducing is 8.04 percent.
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Space signal conti nuity is the time ratio of the period of "healthy" signal to a given time interval, which means there is no probability of non-arranged interrupt in a given time interval. Positioning service continuity is the time ratio that the service satis fies the users' positioning accuracy requirement in a given time interval and a given service area.
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Thus, an increased satellite number will enhance positioning continuity. Brief Summary Interoperability will promote positioning and timing accuracy; positioning and timing availability; and service integrity and service continuity.
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FEASIBILITY ANALYSIS OF INTEROPERABILITY BETWEEN BEIDOU B1 BPSK(2) AND GPS TMBOC Signal Performances Analysis Correlation Peak Figure 21 shows the correlation peak curve of BPSK(1)
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Interoperability at dif ferent frequency improves the anti-jamming and availability of system. Service Performance Availability In China, compared with BeiDou, the interoperability system obtains a 53.33 percent improvement in positioning availability and a 61.23 percent improvement in timing availability; compared with GPS, the interoperability TABLE 10 Simulation Parameters B = 30 MHz a1 = -5 db d = 1/20 Front receive bandwidth Ratio of multipath to direct signal Correlator space
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. Lu_Fig23.eps bitmap FIGURE 24 Multipath error of BPSK(2)
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Brief Summary Comparing the service performance in the second phase of interoperability to that in the first phase, there are improved positioning and timing accuracy, improved positioning and timing availability, enhanced service integrity, and advanced service continuity. FEASIBILITY ANALYSIS OF INTEROPERABILITY BETWEEN BEIDOU TMBOC AND GPS TMBOC Signal Performance Analysis Correlation Peak The correlation peak curve has a direct relation with ranging accuracy, antimultipath, and anti-jamming performance.
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TMBOC(6,1,4/33) -60 -65 -70 -75 -80 -85 -90 -95 -100 -1.5 -1 -0.5 0 0.5 1 1.5 7 x 10 FIGURE 26 Power spectrum envelopes of TMBOC and CBOC.
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Lu_Fig27.eps TABLE 12 Simulation Parameters Delt = 5 B = 0.2 IntTime = 0.004 Frequency space of power spectrum Loop bandwidth Integral time
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Lu_Fig28.eps TABLE 13 Simulation Parameters Delt = 5 B = 0.2 IntTime = 0.004 Frequency space of power spectrum Loop bandwidth Integral time
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Lu_Fig29.eps TABLE 14 Simulation Parameters Delt = 5 IntTime = 0.004 Dllw = [0.1 0.2 0.5 0.75 1] d = 1/24 Frequency space of Integral time Loop bandwidth Correlator space power spectrum
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Lu_Fig30.eps TABLE 15 Simulation Parameters Delt = 5 Dllw = 0.5 Dllw = [0.1 0.2 0.5 0.75 1] d = 1/24 Frequency space of Loop bandwidth Loop bandwidth Correlator space power spectrum
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Lu_Fig31.eps bitmap TABLE 16 Simulation Parameters Delt = 5 Dllw = 0.5 IntTime = 0.004 s d = 1/24 Frequency space of Loop bandwidth Integral time Correlator space power spectrum
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FIGURE 32 Multipath running average error. Lu_Fig32.eps bitmap
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Lu_Fig33.eps bitmap
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Lu_Fig35.eps bitmap
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Lu_Fig37.eps bitmap
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When it is compared with BeiDou, the interoperability system obtains a 17.75 percent improvement in positioning accuracy and a 20.14 percent improvement in timing accuracy. In the United States, for an interoperability constellation of BeiDou + GPS, the average PDOP reduction is 35.10 percent compared with that of GPS and the average TDOP reduction is 36.66 percent.
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When it is compared with BeiDou, the interoperability system obtains a 17.75 percent improvement in positioning availability and a 20.14 percent improvement in timing availability. In the United States, for an interoperability constellation of BeiDou and GPS, the average PDOP reduction is 35.10 percent and the average TDOP reduction is 36.66 percent.
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74 GLOBAL NAVIGATION SATELLITE SYSTEMS 3. With the development of each system, interoperability between the two systems will deepen.
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