Showing papers on "GPS/INS published in 1981"

Training evaluation process

Abstract: An air training evaluation process which corrects the position and velocity sensed by an aircraft's inertial navigation system (INS) to obtain more accurate data on the aircraft's position during an engagement. In carrying out the process the aircraft's on-board INS system is employed to obtain pre-flight data on position and velocity, data on position and velocity during the engagement, and post-flight data on position and velocity. The pre-flight data on position and velocity and the post-flight data on position and velocity are compared with independently determined data on the pre-flight position and velocity of the aircraft and with independently determined data on the post-flight position and velocity of the aircraft respectively to obtain pre-flight error functions and post-flight error functions on position and velocity. These functions and the known time variant drift characteristics of position and velocity of the INS are employed to derive position and velocity correction functions during the time of the engagement. The position and velocity correction functions are employed to correct the INS data on position and velocity during the engagement. The corrected data then are employed to display post-flight, a more accurate position of the aircraft during the engagement relative to background portrayals of features or terrain on the earth. During an engagement of two or more aircraft, aircraft-to-aircraft or aircraft-to-ground corrections may be made to the corrected INS data post-flight for further enhancement of accuracy of the INS data.

Real-Time GPS and LORAN-C Dynamical Performance for Critical Marine Applications

Abstract: With system biases removed both LORAN-C and GPS can provide excellent real time position fixing for low-dynamics platforms. Nevertheless it is wise to understand the fundamental limitations which exist for each system in real-time applications. In addition to emitter geometry, the receiver/navigator architecture and user platform model must be incorporated. In this paper a new statistical error analysis approach is employed which accounts for these factors, and which allows determination of error dynamics experienced during signal faults. The approach enables a direct comparison of LORAN-C and GPS under identical dynamical conditions. A brief overview of the analytical technique is given, and normal and signal fault results presented for aided and unaided rho-rho LORAN-C processors, and for sequential and parallel GPS processors. GPS performance is based on the 6 \times 3 18 satellite GPS constellation. LORAN-C performance is for the Northeast chain.