Galileo EU/ESA GPS USA GLONASS Russia Global Navigation Satellite Systems GNSS Accuracy 10m or better Compass China Planned India, Japan, Korea

Space Based Augmentation Systems Improves GNSS accuracy to 3 metres

Part copied from GNSS Errors Geometry up to 100mOrbits up to 5m Canyon Effect – 1 metre Ionospheric & Tropospheric diffraction metres Timimg errors 4m – Rounding errors 1m

Ionospheric effects ± 5 metres Shifts in the satellite orbits ± 2.5 metres Clock errors of the satellites' clocks ± 2 metres Multipath effect ± 1 metre Tropospheric effects ± 0.5 metre Calculation & rounding errors ± 1 metre All adds up to +- 15m – 10m typically stated With EGNOS still +-3 to 5m according to this source However +- 1m considered realistic

R1 Ephemeris – Actual Position of the Satellite Time – determines how far away we are R1 Geometry locates us anywhere on the surface of a sphere

R1 Ephemeris – Actual Position of the Satellite Time – determines how far away we are R1 Geometry locates us anywhere on the surface of a sphere Intersect 2 Spheres gives a ring R2

R1 Ephemeris – Actual Position of the Satellite Time – determines how far away we are R1 Geometry locates us anywhere on the surface of a sphere Intersect 2 Spheres gives a ring Intersect 3 Spheres gives 2 points 4 spheres gives a 3D position R2 R3

CODE DIVISION MULITPLE ACCESS – CDMA SPREAD SPECTRUM GNSS DATA SPREADING CODE +TRANSMISSION RECEPTIONCORRELATOR DATA OR PRN

Cold Start – Load The Almanac – where are the satellites Warm start – get satellite data and extract Ephemeris (position) and time Calculate UTC Do Geometry and get a 3D fix Use SBAS to correct Fix Use Regression to get better accuracy ASSISTED GPS – this is a technique whereby another source of location data is used to enable the device to start seeking the most apprpriate satellites. E.G. CELL-ID, dead reckoning or just memeory

Space Based Augmentation Systems Improves GNSS accuracy to 3 metres

INTRODUCTION TO DATA OVER GSM ANALOGUE – e.g V22 etc SHORT MESSAGE SERVICE – SMS GPRS BASIC SMS COMMANDS AT+CMGS=” ” > ENTER TEXT CONTROL Z AT+CMGR=NN AT+CMGD=NN AT+CMGW=” ” > ENTER TEXT CONTROL Z AT+CMSS = NN