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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)
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?
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…
Code-minus-Carrier
Code-minus-Carrier
CMC noise stats
68% (“1σ”)
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)
RTKlib runs
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
https://jason.rokubun.cat
Post Processing Kinematic (PPK) serviceMore than 10000 ref. stationsSupports GNSS Logger, Rinex, Ublox, SeptentrioAPI for task automation
