Exercise1 2016
Exercise1 2016
Exercise1 2016
Q3)
The same satellite in Q2 carries a 300 MHz transmitter.
a. Determine the maximum frequency range over which the received signal would shift
due to Doppler effects if received by a stationary observer suitably located in space.
Note: the frequency can be shifted both up and down, depending on whether the satellite
is moving towards or away from the observer. You need to determine the maximum
possible change in frequency due to Doppler (i.e. 2Df).
Q4)
What are Keplers three laws of planetary motion? Give the mathematical formulation of
Keplers third law of planetary motion. What do the terms perigee and apogee mean
when used to describe the orbit of a satellite orbiting the earth?
A satellite in an elliptical orbit around the earth has an apogee of 39,152 km and a perigee
of 500 km. What is the orbital period of this satellite? Give your answer in hours.
Q5)
An observation satellite is to be placed into a circular equatorial orbit so that it moves in
the same direction as the earths rotation. Using a synthetic aperture radar system, the
satellite will store data on surface barometric pressure, and other weather related
parameters, as it flies overhead. These data will later be played back to a controlling
earth station after each trip around the world. The orbit is to be designed so that the
satellite is directly above the controlling earth station, which is located on the equator,
once every 4 hours. The controlling earth stations antenna is unable to operate below an
elevation angle of 10o to the horizontal in any direction. Taking the earths rotational
period to be exactly 24 hours, find the following quantities:
a. The satellites angular velocity in radians per second.
b. The orbital period in hours.
c. The orbital radius in kilometers.
d. The orbital height in kilometers.
e. The satellites linear velocity in meters per second.
CME 511: Satellite Communication 2016
Q6)
What is the difference, or are the differences, between a geosynchronous satellite and a
geostationary satellite orbit? What is the period of a geostationary satellite? What is the
name given to this orbital period? What is the velocity of a geostationary satellite in its
orbit? Give your answer in km/s.
A particular shuttle mission released a TDRSS satellite into a circular low orbit, with an
orbital height of 270 km. The shuttle orbit was inclined to the earths equator by
approximately 28o. The TDRSS satellite needed to be placed into a geostationary transfer
orbit (GTO) once released from the shuttle cargo bay, with the apogee of the GTO at
geostationary altitude and the perigee at the height of the shuttles orbit. (i) What was the
eccentricity of the GTO? (ii) What was the period of the GTO? (iii) What was the
difference in velocity of the satellite in GTO between when it was at apogee and when it
was at perigee?
Q7) An interactive experiment is being set up between the University of York, England
(approximately 359.5oE, 53.5oN) and the Technical University of Graz, Austria
(approximately 15oE, 47.5oN) that will make use of a geostationary satellite. The earth
stations at both universities are constrained to work only above elevation angles of 20o
due to buildings, etc., near their locations. The groups at the two universities need to find
a geostationary satellite that will be visible to both universities simultaneously, with both
earth stations operating at, or above, an elevation angle of 20o. What is the range of sub
satellite points between which the selected geostationary satellite must lie?
Q8) The state of Virginia may be represented roughly as a rectangle bounded by 39.5o N
latitude on the north, 36.5oN latitude on the south, 76.0o W longitude on the east, and
86.3oW longitude on the west. If a geostationary satellite must be visible throughout
Virginia at an elevation angle no lower than 20o, what is the range of longitudes within
which the sub-satellite point of the satellite must lie?
Q9) Most commercial geostationary communications satellites must maintain their orbital
positions to within 0.05o of arc. If a geostationary satellite meets this condition (i.e. it
has an apparent motion 0.05o of arc N-S and 0.05o of arc E-W, as measured from the
center of the earth), calculate the maximum range variation to this satellite from an earth
station with a mean elevation angle to the center of the satellites apparent motion of 5o.
You may assume that the equatorial and polar diameters of the earth are the same.