Low Earth Orbit Systems

Question 1

What is the orbiting altitude of the Iridium satellite communications system?

Answer 1

485 miles

Question 2

What frequency band is used by the Iridium system for telephone and messaging?

Answer 2

1616 -1626 MHz

Question 3

What services are provided by the Iridium system?

Answer 3

Digital voice and Data at 2.4 kbps

Question 4

Which of the following statements about the Iridium system is true?
•There are 48 satellites in orbit in 4 orbital planes.

•The orbital period is approximately 85 minutes.

•The inclination of the orbital planes is 55 degrees.

•There are 48 spot beams per satellite with a footprint of 30 miles in diameter.

Answer 4

There are 48 spot beams per satellite with a footprint of 30 miles in diameter.

Question 5

What is the main function of the COSPAS-SARSAT satellite system?

Answer 5

Monitor 406 MHz for distress calls from EPIRBs

Question 6

How does the COSPAS-SARSAT satellite system determine the position of a ship in distress?

Answer 6

By measuring the Doppler shift of the 406 MHz signal taken at several different points in its orbit.