You will prepare and submit a term paper on GPS Satellite Frameworks and Constellation. Your paper should be a minimum of 1750 words in length. The GPS constellation comprises 24 satellites in 6 orbital planes. The constellation has four satellites per plane. The constellation can further accommodate only 2 satellites to fill the slots. There are certain satellites, which change their position and do not occupy a fixed position in the constellation. Orbital radius is about 16000 miles from centre of the earth. At present, there is 4 GPS satellite constellation which includes, Block 1, Block 2, Block 2a, and Block 2r satellite constellations.
US, Germany, France, and Russia have their own system to meet the requirements of their states. Comprehensive policies have been made and implemented by all countries to make the system error-free (Rizos, 1999).
Now there are 27 satellites of the Block series present in the orbit. Their task is mainly to replace satellites on failure that is why these satellites are treated as spares. “Moth-balled” satellites are present to meet the requirement of replenishment in the constellation. Block 1 satellites are different from other Block series satellites. These all have been launched to different inclination in their orbits (Rizos, 1999).
The block 1 satellites were launched in the 80s as testing satellites to test the different systems. This mission did not succeed because out of 11 launched satellites, none gave the desired results. The Block II satellites were launched one by one and nine spacecraft were launched. The Block IIA satellites were more upgraded than Block 11. The second batch of these satellites comprised of 19 spacecraft of the operational series. The Block IIR satellites were a replacement series launched after Block 11A (Rizos, 1999).
The user segment comprises all GPS users in different countries. GPS receivers have been provided with antenna using different frequencies received from satellites. The clock used in the system is known as a crystal oscillator. GPS display screen has multiple options for users. They can navigate to different locations using the user screen. The number of channels for the receiver has been increased from a few receivers to about 100 (Leick, 1995).