Pseudoranges from your Android smartphone

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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Thank you

Questions?

Lukasz.Bonenberg@nottingham.ac.uk

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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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