The Possibility of Precise Automobile Navigation using GPS/QZS L5 and (Galileo E5) Pseudo ranges

Transcription

1 The Possibility of Precise Automobile Navigation using GPS/QZS L5 and (Galileo E5 Pseudo ranges ION ITM ITM 013 Hiroko Tokura, Taro Suzuki, Tomoji Takasu, Nobuaki Kubo (Tokyo University of Marine Scienceand Technology

2 Outline Background Objective Multipath error estimation methods Static ti and kinematic experiment Test results Conclusion 1

3 Background GPS L5 up to 4 by 01 L5 is broadcast from 3 satellites (PRN1/4/5 QZS L5 up to 4 by 017 Galileo E5AltBOC :cmlevel accuracyunderopensky under

4 L5 Signal Tracking by SDR (PRN Correlation Value L5 signal Standard L1 C/A GPS PRN1 01/8/16 Open Sky Elevation:45 deg. 10ms Integration FE: Fraunhofer SF: 40.96MHz Delay (m 3

5 Multipath Envelope (hardware simulator check: MP is set 6dB lower than Direct Consumer receiver Pseudo ra ange error rs [m] Geodetic receiver Multipath Delay [m] Consumer receiver is vulnerable to multipath delay even over 100m 4

6 Multipath Envelope (close up Pseudo range err rors [m] Geodetic receiver Multipath Delay [m] small difference between L1 and L5 Multipath in L1 has been imped 5

7 Performance in Urban Areas Vehicles in dense urban areas with geodetic receiver DGPS in Tokyo RTK in Tokyo Several applications require high accuracy (RTK far from perfect at present 6

8 Objective Pseudo range observations from L5 in both GPS and QZS are basically robust against multipath. It can be used for high h reliable and accurate application without Ambiguity Resolution. L5 performance has not been investigated because satellites with L5 are few. The Question: Dose pseudo ranges of new signals really work well in urban areas? 7

9 Estimation of Multipath Error Code Carrier Carrier difference(cc differnce differnce Effective for static data Cycle slip happens a lot for kinematic data impossible to extract multipath for kinematic data Proposed method Separating Multipath Errors for Vehicle 8

10 CC difference CC difference L1 = P x Φ x Φ CC difference L5 =P x Φ x Φ1 P : Pseudo range measurement Φ : Carrier phasemeasurement Dual frequency receivers can effectively remove the ionospheric delay Offset average Use both Pseudo range and Carrier phase Effective for only static data 9

11 Proposed Method Separating Multipath Errors for Vehicle Higher Elevation SV Reference SV Precise Rover Position + Double Difference 4 Different Combinations of Multipath and Noise Code minus Carrier Difference Extraction of Target Multipath and Noise Target Multipath and Noise Precise Rover Position Rover Reference Receiver 10

12 Separating Multipath Errors for Vehicle P ( mp ( mp ( P c ( dt c( dt c ( dt c( dt noise noise P dt dt dt dt ( P ion ion ion ion ( mp ( mp P tropo tropo noise tropo tropo noise sv sv sv sv 1 mp mp mp mp noise noise noise noise Target = + + Raw Data Measurements Computed by each CC Difference : Target SV : QZS (Elevation angle >

13 Proposed Method Separating Multipath Errors for Vehicle Higher Elevation SV Reference SV Precise Rover Position + Double Difference 4 Different Combinations of Multipath and Noise Code minus Carrier Difference Cc difference 1 Rover Reference Receiver 1

14 Separating Multipath Errors for Vehicle P ( mp ( mp ( P c ( dt c( dt c ( dt c( dt noise noise P dt dt dt dt ( P ion ion ion ion ( mp ( mp P tropo tropo noise tropo tropo noise sv sv sv sv 1 mp mp mp mp noise noise noise noise Target = + + Raw Data Measurements Computed by each CC Difference : Target SV : QZS (Elevation angle >

15 Proposed Method Separating Multipath Errors for Vehicle Higher Elevation SV Reference SV Precise Rover Position + Double Difference 4 Different Combinations of Multipath and Noise Code minus Carrier Difference Cc difference Rover Reference Receiver 14

16 Separating Multipath Errors for Vehicle P ( mp ( mp ( P c ( dt c( dt c ( dt c( dt noise noise P dt dt dt dt ( P ion ion ion ion ( mp ( mp P tropo tropo noise tropo tropo noise sv sv sv sv 1 mp mp mp mp noise noise noise noise Target = + + Raw Data Measurements Computed by each CC Difference : Target SV : QZS (Elevation angle >

17 Proposed Method Separating Multipath Errors for Vehicle Higher Elevation SV Reference SV Precise Rover Position + Double Difference 4 Different Combinations of Multipath and Noise Code minus Carrier Difference Cc difference 3 Rover Reference Receiver 16

18 Separating Multipath Errors for Vehicle P ( mp ( mp ( P c ( dt c( dt c ( dt c( dt noise noise P dt dt dt dt ( P ion ion ion ion ( mp ( mp P tropo tropo noise tropo tropo noise sv sv sv sv 1 mp mp mp mp noise noise noise noise Target = + + Raw Data Measurements Computed by each CC Difference : Target SV : QZS (Elevation angle >

19 Proposed Method Separating Multipath Errors for Vehicle Higher Elevation SV Reference SV (QZS is very useful Precise Rover Position + Double Difference 4 Different Combinations of Multipath and Noise Code minus Carrier Difference Extraction of Target Multipath and Noise Target Multipath and Noise Precise Rover Position Rover Reference Receiver 18

20 Test and Results 1. Static Test 1 (Toyosu,Tokyo Tokyo long distance (approx. 30m from building. Static Test (campas,tokyo short distance (<10m from building 3. Kinematic Test 1 (tukishima, Tokyo 4. Kinematic Test (edagawa, Tokyo Validation for proposed method Estimate multipath error using proposed method Target : GPS PRN1 PRN1 (transmitting both L1 and L5 19

21 Static Test 1 (Toyosu,Tokyo 1/13/ 01 (GPSTIME 0:30~ Geodetic Receiver 60 min Hz 5 8 satellites in view over 15 degrees elevation Target SV : GPS PRN 1 (L1,L5 Reference SV : QZS 1 (L1,L5 L5 Precise position was computed by post processing Building Rover Receiver 30m W N S Long delay multipath using proposed method to extraction the PRN 1 multipath 0 E

22 Static Test 1 Multipath Errors (no smoothing [m] GPSTIME [s] [] σ [m] L L

23 Static Test 1 Multipath Errors (100s smoothing [m] We just set receiver parameter as 100s for smoothing GPSTIME [s] [] σ [m] L L1 0.1

24 Static Test (campas,tokyo 1/14/ 01 (GPSTIME 0:30~ N Geodetic Receiver 60 min Hz 5 9 satellites in view over 15 degrees elevation Target SV : GPS PRN 1 (L1,L5 Reference SV : QZS 1 (L1,L5 L5 Precise position was computed by post processing Rover Receiver 9m Building W S Short delay multipath using proposed method to extraction the PRN 1 multipath 3 E

25 Static Test Multipath Errors (no smoothing [m] σ [m] L L GPSTIME [s] 4

26 Static Test Multipath Errors (100s smoothing [m] 3 We just set receiver parameter as 100s for smoothing GPSTIME [s] σ [m] L L

27 [m] Validation adao of Our Proposed Method MP errors derived from cc difference MP errors derived from proposed method GPSTIME [s] Multipath for PRN 1 derived from cc difference match 1 Multipath for PRN 1 derived from Proposed Method 6

28 [db] Temporal Carrier to Noise oseratio GPSTIME [s] Another type of geodetic receiver shows almost same difference level (4 5dB between L1 and L5 although h the maximum level lwas different. 7

29 Kinematic Test 1 (tukishima, Tokyo 11/3/ 01 Geodetic Receiver 0 min 5 Hz satellites in view over 15 degrees elevation Target SV : GPS PRN 1 PRN (L1,L5 L5 Reference SV : QZS 1 (L1,L5 Precise position was computed by post processing s smoothing 8 7 Fix rate[%] RTK m (Post Processed RTK Plots 8

30 Kinematic Test 1 Multipath Errors [m] GPSTIME[s] Enabled percentage[%] L L

31 Kinematic Test 1 Multipath Errors [m] abs(mp < 5m GPSTIME[s] σ [m] L L

32 Kinematic Test (edagawa, Tokyo 1/7/01 Geodetic Receiverei er 35min 5 Hz 4 9 satellites in view over 15 degrees elevation Target SV : GPS PRN 1 PRN (L1,L5 L5 Reference SV : QZS 1 (L1,L5 Precise position was computed by post processing s smoothing Fix rate[%] RTK m 31 31

33 Kinematic Test Multipath Errors [m] Enabled 0 percentage[%] L L GPSTIME [s] 3

34 Kinematic Test Multipath Errors [m] abs(mp < 5m σ [m] L L GPSTIME [s] 33

35 Conclusion Pseudo range observables from L5 are basically robust against multipath. We were able to estimate t multipath th errors for moving targets by using the proposed method. The multipath mitigation performance bt between L1 and L5 was not so different at present. Using L5 instead of L1 will be practical in the future without special correlator. 34

36 Future work Further investigation for L5 signal is required because manufactures are still developing the tracking technique for new L5 signal. Software defined GNSS receiver can be used to evaluate it. 35

37 Thank you very much for your kind attention!