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

2. Space Based Augmentation Systems Improves GNSS accuracy to 3 metres

3. GNSS Errors Ionospheric & Tropospheric diffraction 10 + 1 metres
Canyon Effect – 1 metre
Part copied from
Timimg errors 4m – Rounding errors 1m
Geometry up to 100m
Orbits up to 5m

4. 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

5. 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

6. 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

7. R2 R1 R3
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

8. CODE DIVISION MULITPLE ACCESS – CDMA SPREAD SPECTRUM
GNSS DATA +
TRANSMISSION
SPREADING CODE
CORRELATOR
RECEPTION
DATA OR PRN

12. Coarse Acquistion
1023 bits, 1.023MHz = 1 ms repetition rate
Precise Code
× 1012 bits long (6,187,100,000,000 bits)
Part of 2.35 × 1014 bits in length (235,000,000,000,000 bits)
10.23MHz
May be modulates with a W-code to prevetn Spoofing
Navigation Message
50 BPS – Date & Time – Ephmeris – Almanac
1500 Bit frame in 5 sub-frames of 300 bits - each takes 6 seconds to arrive

13. 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

14. Space Based Augmentation Systems Improves GNSS accuracy to 3 metres

15. 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=” ”
AT+CMSS = NN