The document discusses Global Navigation Satellite Systems (GNSS) and is a presentation by Niels Kaare Hjaltelin Rasmussen from Geoteam. It provides an agenda that covers topics like trilateration, polarization, relative measurements, ionosphere effects, code vs phase measurements, VRS vs single base systems, dilution of precision (DOP), and accuracy levels. It also briefly introduces Geoteam, which has 20 employees, 7 million euro in turnover, and expertise in GNSS technologies.

1. Niels Kaare Hjaltelin Rasmussen
Skovskolen 2014, april 30
www.geoteam.dk
GNSS

2.  Intro
 About Geoteam and me
 Trilateration and the simple formula
 Polarisation and multipath
 Relative measurements
 Ionosphere
 Code vs phase measurements
 VRS vs single base
 DOP and GNSS
 Accuracy steps
 Filters and relativs vs. absolute
Agenda
2

3.  20 Employes
 Turnover 7 mio euro
 Experts in GNSS
 We own:
 Cand. geom
 Business Development
 Business Administration
About Geoteam and me
3

4. Trilateration
4

5. Simple formula!
5
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1

6. Polarization
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7. Multipath 1 of 2
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8.  Solution: Good antenna
Multipath 2 of 2
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9.  EGNOS
 DGPS
 Single station RTK
 VRS – GPSnet.dk
Relative measurements 1 of 2
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10. Relative measurements 2 of 2
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11. Space weather
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12. NOAA Space Weather Prediction Center
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13. < 10 km
> 10 km
Ionosphere
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14.  Big difference!
Code vs phase measurements
14

15. SBAS - EGNOS
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16. VRS vs single base
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17.  PDOP > 6 is unreliable
 PDOP < 4 is good
 PDOP < 2 is really good
Satellit konstellation - PDOP
Good PDOP Bad PDOP
17

18. DOP
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19.  NAVSTAR GPS – GPS – USA
– 32 satellites
 Glonass – Russia
– 22 satellites
 Beidou – China
– 14 satellites
 Galileo
– 6 satellites
GNSS’
19

20.  Cellphone/car
– Code, bad antenna
 Better antenna
– Code, avoid multipath
 SBAS
– Relative measurements - big area
 DGPS
– Realative measurements - small area
 RTK single base station
– Phase measurements
 RTK VRS
– Phase measurements
Typical accurary steps
20

21. Don’t be cheated by filters!

22. Relative vs absolute postions

23. www.geoteam.dk
Questions?