Smartphone dual-freq. GNSS data preprocessing for high ... · Android Raw Measurement Task Force...
Transcript of Smartphone dual-freq. GNSS data preprocessing for high ... · Android Raw Measurement Task Force...
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Android Raw Measurement Task Force
Wednesday, June 26th 2019
Smartphone dual-freq. GNSS data preprocessing for high accuracy
applications
Miquel Garcia (CTO), Xavier Banqué (CEO)
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Background• Previously in Android Task Force … a cliffhanger
First smartphone with L1/L5/E5a GNSS
• Strong focus on GNSS navigation filters/strategies
• Usage of open-source packages (e.g. RTKLIB):– Very popular in various communities – In Jason (Rokubun PPK service) as interim engine
What about data editing?
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Data editing• Reject fault (potentially offending)
measurements (i.e. code and phase outliers)• Cycle slip detection• Focus on real time
• Several GNSS data combinations for this purpose: Carrier-minus-Code (CMC), phase narrow-lane…
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Code-minus-Carrier
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Code-minus-Carrier
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CMC noise stats
68% (“1σ”)
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Cycle slips• ADR_STATE_CYCLE_SLIP too strict to flag cycle
slips• Usage of epoch-to-epoch CMC to flag slips
If|cmc[n+1]–cmc[n]|>3*σ_cmcàslip!
• Suitable for real time editing• Works in single-frequency receivers• L1 and L5/E5a can be used for phase-only
cycle slip detection (narrow lane)
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RTKlib runs
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Processing tips• Weight by SNR, not elevation weighting (as
done by RTKLIB) if possible• Remove outliers always, regardless SNR• Use Android Multipath getMultipathIndicator()
indicator to flag gross code outliers • Use CMC-based cycle slip detection
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https://jason.rokubun.cat
Post Processing Kinematic (PPK) serviceMore than 10000 ref. stationsSupports GNSS Logger, Rinex, Ublox, SeptentrioAPI for task automation