Dead Reckoning GPS carrier phase
The practice of dead reckoning (a pictorial expression of uncertain origin) is five centuries. In its original form, study tours were gradually drawing a sailor with dividers for distances, compass directions to (with corrections for magnetic variation and deviation). These measures were included in the rate charged at intervals, until a fix was made available (eg, brand or star gazing).
ModernTechnology has given more accurate calculation of the dead as Doppler radar or inertial navigation systems. Discussed here is an alternative for estimation, the high precision using sequential changes in transport. The method successfully validated in flight with the GPS, it is easy to use with the satellites of other GNSS constellations (Galileo, GLONASS, etc.) Interoperability is a feature to attract more attention, sequentialchange in carrier phase is much easier to mix the same steps, and measures have been taken as sensitive to ephemeris errors (even with satellite mislocation, the changes are exactly in the position of the satellite).
Even with the use of only a constellation (GPS reported the results of flight tests here), when changes in the support phase at intervals of 1 second important benefits. Your benefits are described are explained in relation to the limitations on the cart pathThe phase information is generally used. phase measurements are generally a product of the wavelength L-band for an amount in the form (integer + fraction), the report accurately measured, while the majority of their choice to be multiplied. If the group is known with precision, the result is obviously very close. Even the most sophisticated methods of extraction, but sometimes a very inaccurate result. The result can be disastrous, and cantoo long a delay before the correction is possible. The removal of this possibility a strong motivation for the system described here.
With the formation of a second changes in all phases of transport are ambiguous, ie, the figures are still unknown, they cancel in the formation of sequential differences. In addition, the discontinuities can be tolerated, a signal is immediately acceptable to just two phases of society differ in a number of meetingsA single test that RAIM. The technique is particularly effective with beneficiaries through FFT-based processing, which allows access without conditions, without phase distortion (provides a limited subset of a ring of the track) all the cells of the correlation.
Another advantage is the subtle but important changes in the acceptance phase mask carrier. Compensation ionosphere and troposphere changes very little over a second time. Conventional systems are designed to eliminate stepssatellites at low altitude. In particular to improve the dissemination of geometric constraint, avoiding unnecessary loss of important information. Demonstration that the theft occurred when a satellite goes below the horizon, a nickname was of course rejected, but all the changes in phase 1, the second company were quite acceptable until the satellite has been more apparent.
Additional (lower) issue and requires much more rigorous analysis of the results of the correlation between sequentialA second phase change observed. The question is examined in detail and presented in the following sections of chapter 5 of the GNSS-guided navigation and monitoring of peace.
computing capacity without dead-IMU was tested flight if dm / RMS speed error to pass a couple of seconds of railways (section 8.1.2, pages 154-162 of the book above). With a low cost IMU is the accuracy in the table at the bottom of the page description on this page (also shown on page 104the book). All increase the size of Phase 1-sec remaining were zero or 1 cm for the seven satellites (six differences over-SV) were observed at that time. For almost an hour to fly at high altitude (ie not start the game, in which the uncertainty of the error vector induced greater than the lever arm), cm / s velocity precision achieved RMS.
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