B-1B Doppler error compensation based on flight data analysis

Numerous B-1B flight tests with good tracking reference data have made possible a new level of Doppler error analysis. The analysis involves the fitting of the Doppler error data to aircraft dynamics data. Reference velocity truth is provided by the Northrop Astro Inertial System (NAIS). The Doppler errors are expressed as scale factor and bore sight errors. Doppler and NAIS velocity are recorded together with dynamics data. The dynamics data are used as independent variables in attempts to model the observed Doppler errors. A modified group method of data handling (GMDH) procedure is used for automated search over thousands of possible models. The Akaike information criterion is used to select the best polynomial fit and avoid fitting to noise. Past attempts to determine the error models for the common strategic Doppler were limited to relatively few different structures. However, with the advent of GMDH, more exhaustive search for cause-and-effect relationships has become possible. The basic GMDH method and extensions are described