A Novel Method to Improve Dynamic Performance of GPS Carrier Tracking Loop with INS Aiding

It is inclined to lose the tracking of a GPS receiver´s carrier loop in noisy jamming or high dynamic environment, therefore, INS´s velocity information is often used to expand the equivalent bandwidth of GPS receiver´s tracking loop, reduce loop´s bandwidth, improve high dynamic adaptability and Signal-noise ratio. However, because of the discretization of INS´s velocity, the rapidly changing control quantity for NCO under high dynamic environment makes the loop tracking unstable. For this reason, tracking loop with INS´s acceleration information aiding based on LM algorithm of BP neural network is proposed. Firstly, the effect of INS´s update frequency on a typical second-order tracking loop is analyzed, then the model of BP neural network based on LM algorithm is built, and the INS instantaneous velocity and acceleration as input variables to obtain the estimate of the loop NCO through training the network and compensation the loop NCO, after training is completed, we can create the appropriate database, which the data can be called directly. The results show that this method enhances loop´s tracking speed and stability, improves loop´s adaptability to dynamic stress.