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Sensors

Sensors​

Sensors are used by Algorithms to quantify position, velocity, and attitude. Different Algorithms require different types of sensors. The available types are: Optical Attitude (e.g. Star Tracker), Position (e.g. GPS), Direction (e.g. Earth Sensor), Angular Velocity (e.g. Gyroscope), and Vector (e.g. Magnetic Field Sensor).

Any sensor can be associated to a set of Conditions. The sensor will only produce data if all of the Conditions are valid. If no Conditions are selected, the Sensor will always produce data.

Optical Attitude Sensor​

These are used for Attitude Determination. To model an optical attitude sensor, the simulation requires the user to provide inputs on planar and roll accuracy. One Sigma Cross-Axis Error is the sensor’s cross-axis standard deviation for attitude, and the One Sigma Boresight-Axis Error is the radial error (standard deviation) around the center vector of the sensor.

Generic Position Sensor​

Generic position sensors provide a 3D-vector position estimate for the satellite; these are used for Orbit Determination. Input the standard deviation of distance error, assumed to be the same for each dimension.

GNSS Receiver​

GNSS receivers provide estimates for the position and clock bias of the satellite as well as the position dilution of precision (PDOP) and time dilution of precision (TDOP) of the solution.

The GNSS receiver requires that you specify at least one space target group that the receiver will use as transmitters to iteratively solve for a solution. During the simulation, the receiver requires that there are at least 4 transmitters in the group that have direct line of sight to the satellite and are not in the same plane. If you specify a Field of View for the GNSS receiver, the receiver will only consider transmitters that are within the specified Field of View.

The receiver also requires a one sigma pseudorange error, which is the assumed standard deviation of the error in the receiver-measured distances between the satellite and the transmitters, as well as an iteration tolerance, which is the maximum difference in position between successive iterations before the receiver stops iterating for a solution.

Direction Sensor​

Direction sensors provide information on the orientation of an external reference with respect to the satellite; these are used for Attitude Determination. Input a Reference Vector and the angle error (standard deviation) between the actual direction and measured.

Angular Velocity Sensor​

Angular velocity sensors measure the angular rate of the spacecraft in the body frame; these are used for Attitude Determination. Input the standard deviation of the error.

Target Attitude Sensor​

Target attitude sensors provide a quaternion estimate of a target's orientation with respect to the observer's body frame. These require a Space Target, a One Sigma Boresight-Axis Error, and a One Sigma Cross-Axis Error.

Target Position Sensor​

Target position sensors provide a 3D-vector position estimate of a target's position with respect to the observer's body frame. These require a Space Target and a One Sigma Distance Error.

Target Range Sensor​

Target range sensors provide a scalar magnitude estimate of the distance between an observer and a target. These require a Space Target and a One Sigma Distance Error.

Target Range Rate Sensor​

Target range rate sensors provide a scalar estimate of the change in range between an observer and a target. These require a Space Target and a One Sigma Velocity Error.

Vector Sensor​

Vector sensors provide information on the orientation and magnitude of an external reference vector with respect to the satellite; these are used for Attitude Determination. Input a Reference Vector for the vector sensor to measure, the standard deviation of the error and optional select an FoV to limit sense scope and direction. Adding an FoV is equivalent to associating a vector in FoV Condition.