Issues with length As site separation increases, the differential ionospheric delays increases, atmospheric delay differences also increase making modeling of phase data more difficult For short baselines(<10 km), ionospheric delay can be treated as zero and l 1 and l2 resolved separately For longer baselines this is no longer true and ambiguities must be resolved with lc (and often the MW WL L1-L2 number of cycles) Track features Track uses the melbourne -Webena wide Lane to resolve l1-l2 and then a combination of techniques to determine l1 and l2 cycles separately For short baselines uses a search technique and floating point estimation with L1 and L2 separately For long baselines uses floating point estimate with LC and ionospheric delay constraint05/07/03 12.540 Lec 22 5 Issues with length 05/07/03 12.540 Lec 22 6 Track features separately. separately • As site separation increases, the differential ionospheric delays increases, atmospheric delay differences also increase making modeling of phase data more difficult • For short baselines (<10 km), ionospheric delay can be treated as ~zero and L1 and L2 resolved separately • For longer baselines this is no longer true and ambiguities must be resolved with LC (and often the MW WL L1-L2 number of cycles) • Track uses the Melbourne-Webena Wide Lane to resolve L1-L2 and then a combination of techniques to determine L1 and L2 cycles • For short baselines uses a search technique and floating point estimation with L1 and L2 • For long baselines uses floating point estimate with LC and ionospheric delay constraint 3