A high sensitivity VDFLL utilizing precise satellite orbit/clock and ionospheric products

In the VDFLL, the ranging errors will degrade the positioning accuracy as well as the tracking performances. In the paper, a new VDFLL tracking loop minimizing the ranging error by utilizing precise satellite orbit/clock and ionospheric products has been proposed. Unlike the conventional VDFLL, which treats all the measurement errors as zero-mean Gaussian noise with a high variance, the new VDFLL will first reduce the biases using precise satellite orbit/clock and atmospheric delay data and then assign a lower measurement error variance in the EKF. With reduced ranging errors, the positioning accuracy is improved more than 30% and the ranging error and tracking sensitivity of tracking loop are improved by around 3dB.