Data Acquisition Techniques Global Positioning System GPS GPS

Data Acquisition Techniques

Global Positioning System (GPS)

GPS Segments 3/12/2021 3

GPS Segments • • • Space Segment Control Segment (Monitor Stations on Earth) User Segment 3/12/2021 4

Space Segment • There are 24 satellites but as of February 2007, there are 30 actively transmitting satellites • Orbit the earth in a distance of 20200 km. • The satellites orbit the earth with a speed of 3. 9 km per second • have a circulation time of 12 h sidereal time, corresponding to 11 h 58 min earth time. This means that the same satellite reaches a certain position about 4 minutes earlier each day 3/12/2021 5

Space Segment • Height of the orbits is about 20200 km • In comparison, geostationary satellites like ASTRA or Meteosat –orbit the earth at 42300 km, which is about twice the distance of GPS satellites. • The satellites are arranged on 6 orbital planes, each of them containing at least 4 satellites. 3/12/2021 6

Space Segment • The six planes have approximately 55° inclination (tilt relative to Earth's equator) and are separated by 60° • . 3/12/2021 7

Control Segment • The US Military (US Do. D) operates this segment from the main control site at the Falcon Air Force Base in Colorado Springs, Colorado, USA. • Makes changes needed to keep the satellites on course and doing their jobs properly. • The master control station and four additional monitoring stations (on Hawaii, Ascension Islands, Diego Garcia and Kawajalein) were set up for monitoring the satellites. 3/12/2021 8

Falcon Air Base (Master Control Station) 3/12/2021 9

Satellite tracking Station on Hawaii 3/12/2021 10

Control Segment • During August and September 2005, six more monitor stations of the NGA (National Geospatial-Intelligence Agency) were added to the grid. • England, • Argentina • Ecuador • Bahrain • Australia and • Washington DC 3/12/2021 11

Control Segment 3/12/2021 12

User Segment • User segment hardware contains three parts: the antenna, the receiver, and the data logger; sometimes called a data collector • The data logger is a hand-held computer that contains software to coordinate signal collection and storage, file manipulation and file transfer to and from a computer. Some systems might combine all three elements into a single piece of hardware. • Modern GPS satellite receivers can be built in such a compact way, that they even can be integrated in wrist watches. 3/12/2021 13

User Segment 3/12/2021 14

Car held GPS Receivers 3/12/2021 15

Keychain GPS 3/12/2021 16

Integration 3/12/2021 17