Correct Answer : 12 hours
Explanation : The GPS satellites are in approximately 12 hour orbits( 11 hours, 57 minutes, 57.27 seconds) at an altitude of approximately 11,000 nmi. At any point on Earth, 4 satellites are visible at all times.
Correct Answer : Option (C) : Limit vibration errors
Explanation : The gyros and accelerometers are rigidly mounted on a block with temperature sensors. The block is usually shock mounted to the vehicle to control the bandwidth of the motion sensed at the instruments. Shock mounting limits vibration rectification errors within the errors themselves.
Correct Answer : Option (B) : Coning algorithm
Explanation : Pre-processing the gyro data at a higher rate than the quaternion iteration improves the approximation in the vector change in angle in order to follow the actual motion of the rotation axis closely. The pre-processing algorithm is also called as coning algorithms.
Correct Answer : Option (B) : Euler angles are not easily readable from the gimbals
Explanation : One of the main purposes of gimballed system is to provide a convenient readout of vehicle attitude by reading each of the gimbals angles separately, thereby yielding convenient Euler angle outputs.