Opinion ID: 781499
Heading Depth: 3
Heading Rank: 4

Heading: The Accused SSL Satellites

Text: 40 Lockheed asserts that SSL's Intelsat VII satellites infringe claim 1 of the '772 patent. As discussed above, the '772 patent describes a yaw wheel used in conjunction with a pitch wheel. The SSL satellites do not use a single pitch wheel centered on the pitch axis of the satellite. Instead, the SSL satellites use a pair of V-Wheels that straddle the pitch axis in a V-shape; each V-Wheel operates in a single direction. The attitude of the SSL satellites is controlled by altering the relative speed of the two V-Wheels (V-Mode). 41 In addition to the V-Wheels, the SSL Intelsat VII satellites include a yaw wheel centered on the yaw axis of the satellite, referred to as an L-Wheel. According to SSL, the L-Wheel is activated only when one of the two V-Wheels fails. The L-Wheel rotates in one direction if one V-Wheel fails (L1-Mode), and the other direction if the other V-Wheel fails (L2-Mode). However, the L-Wheel does not operate in both directions during an orbit. That is, the L-Wheel does not slow down to zero speed and reverse direction during an orbital period. Furthermore, while in operation, the L-Wheel never spins more slowly than a certain bias speed in order to offset the partial yaw momentum of the functioning V-Wheel. 42 The SSL satellites continuously monitor and correct roll and pitch pointing errors detected by the earth sensor. While operational, therefore, the speed of the L-Wheel changes continuously during orbit because it responds to actual errors detected while in orbit. The attitude control system of the SSL satellites is also designed to operate effectively during inclined orbit by compensating for the roll pointing error created by inclined orbit. During inclined orbit, the roll bias generator and yaw momentum bias generator of the SSL satellites vary the speed of the V-Wheels or the L-Wheel, intentionally causing the satellite to point north or south. 43 The SSL satellites also include a mechanism to fool the satellite from attempting to correct the intentional roll pointing error detected by the earth sensor. As discussed above, if the SSL satellite earth sensor detects a roll pointing error while the L-Wheel is operational, the speed of the L-Wheel changes in order to correct the detected error. However, when the satellite is intentionally rolled during an inclined orbit, the angle of intentional roll is summed with the roll error output signal of the earth sensor, and the satellite is effectively fooled from correcting for the intentional attitude adjustment.