Abstract
An electro-optical infrared (EO-IR) sensor’s Operational Envelope is the parameter space where the sensor can physically operate. The Valid Operating Region (VOR) is a subset of the Operational Envelope and is the parameter space where the sensor can return calibratable data. The traditional VOR (TVOR) is a small subset of the VOR that is the intended on-orbit operating range for each parameter. Usually, sensors are calibrated only over their TVOR. We describe a method to produce radiometric and Line-of-Sight (LOS) calibrations over the entire VOR, enabling a sensor to perform its mission and return calibrated data through changing operating conditions, such as are experienced early on-orbit or during spacecraft anomalies. This method expands the calibration to compensate for all known input variations, rather than the traditional approach of minimizing input variations. The ground test method described builds a statistical calibration model as ground test data is collected, where the model determines if there is sufficient data in a particular region of the parameter space and where additional data may need to be collected to meet mission LOS and radiometric accuracy requirements. Although more data will need to be collected to span the VOR compared to a calibration process only over the TVOR, this statistical calibration model can guide the ground test and enable optimal data collection.
Condition-Based Calibration of Electro-Optical Infrared (EO-IR) Sensor Systems
An electro-optical infrared (EO-IR) sensor’s Operational Envelope is the parameter space where the sensor can physically operate. The Valid Operating Region (VOR) is a subset of the Operational Envelope and is the parameter space where the sensor can return calibratable data. The traditional VOR (TVOR) is a small subset of the VOR that is the intended on-orbit operating range for each parameter. Usually, sensors are calibrated only over their TVOR. We describe a method to produce radiometric and Line-of-Sight (LOS) calibrations over the entire VOR, enabling a sensor to perform its mission and return calibrated data through changing operating conditions, such as are experienced early on-orbit or during spacecraft anomalies. This method expands the calibration to compensate for all known input variations, rather than the traditional approach of minimizing input variations. The ground test method described builds a statistical calibration model as ground test data is collected, where the model determines if there is sufficient data in a particular region of the parameter space and where additional data may need to be collected to meet mission LOS and radiometric accuracy requirements. Although more data will need to be collected to span the VOR compared to a calibration process only over the TVOR, this statistical calibration model can guide the ground test and enable optimal data collection.