High integrity carrier phase navigation for future LAAS using multiple civilian GPS signals

In near future, there will be two more civilian GPS signals, at 1227.60 MHz and 1176.45 MHz, in addition to the present one at 1575.42 MHz. Of many possible benefits from the three civilian signals, this paper focuses on how to achieve high integrity and continuity in local area differential navigation by using multiple combinations of the carrier wave frequencies of the signals. The carrier frequencies of the three civil signals can be used to form measurements with different wavelengths, both longer and shorter than their own, depending on the specific combination used. By using these combinations in cascade manner, first finding the integer of the signal with the longest wavelength then moving on to a shorter one, the L1 integer can be resolved without using redundant measurements. Since integrity and continuity of differential carrier phase navigation depends on the validity of the integer solution, an integer rounding criterion based on wavelength and measurement noise is developed to verify the solution. Analysis of the integer rounding criterion shows that multiple levels of integrity and continuity for differential carrier phase navigation are possible, depending on the measurement noise level. Sensitivity analysis is carried out to study the effect of receiver noise, multipath delay, ionosphere delay and change in distance between an user and a reference receiver