Patent Document ID: 8427368
Application ID: 13053140
Patent Flag: 1

Claim One:
1. A method for estimating calibration for ground based beam forming in a satellite communications network, the method comprising: obtaining measurements of gain of a first calibration signal retransmitted by one or more satellite elements, the first calibration signal being communicated by a first calibration station located at a first geographic location, the measurements of gain including a first measurement of gain for a first element of the one or more satellite elements retransmitting the first calibration signal; computing weights indicative of a confidence in the obtained measurements of gain for the one or more satellite elements retransmitting the first calibration signal, wherein computing the weights includes computing a first weight indicative of a confidence in the first measurement; accessing a first geodetic radiation gain pattern of the first element, the first geodetic radiation gain pattern being a function of a roll, a pitch, and a yaw of a satellite; computing partial derivatives of the first geodetic radiation pattern with respect to roll, pitch and yaw at a point in the first geodetic radiation pattern corresponding to the first geographic location; obtaining measurements of gain of a second calibration signal retransmitted by one or more satellite elements, the second calibration signal being communicated by a second calibration station located at a second geographic location that is different from the first geographic location; computing weights indicative of a confidence in the obtained measurements of gain for the one or more satellite elements retransmitting the second calibration signal; computing partial derivatives of the first geodetic radiation pattern with respect to roll, pitch and yaw at a point in the first geodetic radiation pattern corresponding to the second geographic location; generating a first cost function using at least the obtained measurements of gain for the one or more satellite elements retransmitting the first calibration signal, the obtained measurements of gain for the one or more satellite elements retransmitting the second calibration signal, the computed weights indicative of the confidence in the obtained measurements of gain for the one or more satellite elements retransmitting the first calibration signal, the computed weights indicative of the confidence in the obtained measurements of gain for the one or more satellite elements retransmitting the second calibration signal, the computed partial derivatives of the first geodetic radiation pattern with respect to roll, pitch and yaw at a point in the first geodetic radiation pattern corresponding to the first geographic location, and the computed partial derivatives of the first geodetic radiation pattern with respect to roll, pitch and yaw at a point in the first geodetic radiation pattern corresponding to the second geographic location; computing values for one or more unknown variables by reducing the first cost function with respect to the one or more unknown variables that are selected from a group consisting of an estimated change in roll error, an estimated change in pitch error, and an estimated change in yaw error; determining a pointing error of the satellite using the computed values; and storing the pointing error.