Establishment of Regional Ionospheric Delay Model in Xi'an Based on Phase Smoothing Pseudo-Range and LS Surface Function

With phase smoothing pseudo-range observed value,a regional ionospheric delay model is established by sequential least squares surface fitting with restrictive conditions.As a result,the average inner precision of the model is 6.9 cm,while the average outer precision is 8.8 cm.We also compare with the electron content calculated by global grid ionospheric delay model.Single frequency-PPP test of the two models have also done,the results show that the precision of regional ionospheric delay model is obviously superior to that of global grid ionospheric delay model.