pseudoranges from your android smartphone
TRANSCRIPT
GPS
Figure courtesy of Prof T Moore1
Android Nougat
©Google2
Pseudoranges from your Android smartphone
Dr. Lukasz Bonenberg
1st Feb 2017
NGI
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Introduction
GPS Navigation Concept
Figure courtesy of Prof T Moore5
Inside Android
©Google6
Looking under the hood
API before v24
//developers.google.com/awareness-location/©Google
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Big picture
©Google9
New API
©Google10
Big picture
©Google11
Sum it up
• Most devs focus on highly abstracted
com.google.android.gms.location
• android.hardware provides Sensors API
• android.location provides raw GNSS
• Last two are difficult to use
• check Google Matlab code
• check my notes and python code
• Google...
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GNSS Observables
GNSS raw data
• Pseudorange/Pseudorange Rate (code)
• HW clock
• Navigation data
• Accumulated Delta Range (Carrier)
• additional information (Doppler, observation uncertainty ,SNR
ect)
Availability varies and might not be enabled on supported chipsets1.
Currently, only Nexus 9 provides most of the raw measurements.
Nexus 5x, Nexus 6, Pixel and Pixel XL only provide code and clocks,
sometimes only if fix.1Qualcomm Snapdragon 650 or 820, Broadcom BCM4774 or Intel WCS2x00
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Carrier phase
Figure courtesy of Prof T Moore15
Carrier phase
• In order to save battery a lot of phones will use duty cycle
which will affect both carrier phase reading and clocks
• Currently only Nexus 9 provides carrier phase
• Read T. Humphrey et al (2016) On the Feasibility of
cm-Accurate Positioning via a Smartphone’s Antenna
and GNSS Chip
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Making it real - live demo
Opportunity and Challenge
GNSS accuracy
Figure courtesy of Prof T Moore19
We are not yet replacing CORS networks
©Google20
or use it for civil engineering...
Figure courtesy of Prof Gethin Roberts and Dr Xiaolin Meng21
Sensors everywhere
William Starkey/CC022
Urban Canyons
Pexels/CC023
Using it
Where should we start ?
• Pseudorange and Doppler in urban canyons
• Teaching
• Mobile hardware differences
• Conversion to other formats RTCM3, RINEX logger
• NMEA logger for messages not already supported
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Some suggestions
• GIS, asset management
• Augmentation and integrity monitoring
• Space weather
• Differential GNSS/RTK using NTRIP and CORS and OS tools
like RTKLib
• Crowdsourced jammer detector
• Crowdsorced earthquake detection
• sensor fusion
• improve position in urban areas (GNSS shadowing)
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Summary
What we covered today
1 Introduction
2 Looking under the hood
3 GNSS Observables
4 Making it real - live demo
5 Opportunity and Challenge
6 Using it
7 Summary 28
Take away
• RAW GNSS will only work with Android 7.x;
• A limited hardware is supported2;
• Open source code is available;
• Commercial companies are interested;
• More creative use of GNSS in mass market applications?
• Privacy concerns.
2Hardware allegedly forced to comply from mid 2017
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Useful links
• my edits to Google code -
https://github.com/DfAC/gps-measurement-tools
• ranges intro in python -
https://github.com/DfAC/AndroidGNSS
• Simon Banville blog - http://www.blackdotgnss.com/
2016/09/20/ppp-with-smartphones-are-we-there-yet/
• Rokybun blog - http://rokubun.cat/2016/06/30/
android-n-preview-gnss-measurements/
• My previous presentations -
http://www.slideshare.net/LukaszKosmaBonenberg
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