This document discusses satellite orbits and positioning systems. It begins by introducing satellite system components like subsystems, uplinks and downlinks. It then defines key terms related to satellite orbits, such as the minimum velocity needed to orbit Earth and different orbit classifications like LEO, MEO, HEO and polar orbits. Multiple access methods for satellites like TDMA, FDMA and CDMA are also covered. The document concludes by providing an overview of the GPS system and its space, control and user segments.

1. By:
Amjad Hassan Khan MK
Lecturer in Electronics
Kristu Jayanti College, Bengaluru

2. Introduction-satellite orbits, Satellite
system; Block diagram, satellite sub
systems, up link, down link, cross link,
transponders (C, band) (Space content),
ground station (simplified Block diagram
of earth station).
Multiple access methods -TDMA, FDMA,
CDMA;
GPS services like SPS and PPS.

4. Definitions and Terminology
• For any object to be placed in an orbit
around the Earth, it is essential for it
to have a minimum velocity of 7.9
km/ sec
• If you want to have a mission to the
moon or beyond, or if you need to go
beyond the gravitational attraction of
earth, you will need to obtain a
minimum speed of 11 km/sec
• Once you get out of Earth’s gravity,
you will continue to travel at that
speed until you enter the
gravitational attraction of another
body.

5. Definitions and Terminology
• When you are out in space, there
will be no atmosphere to create
any drag effects on your space
vehicle
• In order to escape Earth’s
atmospheric effects, you have to
be higher than 1000 km altitude.
• The time taken by a satellite to
execute one complete orbit is
called the period and it is shown
by τ

6. Period of a Satellite
• The time taken by a satellite to
execute one complete orbit is
called the period and it is
shown by τ. Hence, if a satellite
rotates one orbit in 3 hours,
then its period is 3 hours

7. • Elliptical orbits
1. LEO
2. MEO
3. HEO
• Polar Orbits
• Geostationary Satellite Orbit (GEO)

8. • LEO is Low Earth orbit and
it is considered as 160 km
to 500 km of altitude.
Technically, in Low Earth
orbit, the drag effects will
always hinder operations.
• Satellites in LEO will have
very high speeds around
18,000 miles per hour

9. • MEO is Middle Earth
Orbit is a special orbit
that is beyond LEO.
• MEO is usually defined
as 500 Km – 1000 Km

10. • HEO is High Earth orbit
• HEO is defined as orbit above 1000 km in most
literature. It extends to 40,000 km altitude.
• Mostly in HEO, the drag effects would be non existent.
Hence, HEO will have a more stable orbit free from
atmospheric effects, but also it will require much more
energy to put there

11. • These orbits have an
inclination near 90 degrees.
This allows the satellite to
see virtually every part of
the Earth as the Earth
rotates underneath it. It
takes approximately 90
minutes for the satellite to
complete one orbit.

13. https://www.youtube.com/watch?v=6dISKhVdX7g

20. Multiple access methods
• Frequency Division Multiplexing (FDM)
• Time Division Multiplexing (TDM)
• Code Division Multiplexing (CDM)
• Wavelength Division Multiplexing (WDM)

21. Time Division Multiplexing Access (TDMA)

22. Frequency Division Multiplexing Access (FDMA)

23. Code Division Multiplexing Access (CDMA)

25. Global Positioning system (GPS)
• Space segment
• Control segment
• User segment

26. Space segment:

27. Control segment:

28. User Segment: