Method of checking the integrity of the estimation of the position of a mobile carrier in a satellite-based positioning measurement system
Methods of checking the integrity of the estimation of the position of a mobile carrier are provided, the position being established by a satellite-based positioning measurement system, the estimation being obtained by the so-called “real time kinematic” procedures. The method verifies that the carrier phase measurement is consistent with the code pseudo-distance measurement. The method comprises a step of calculating the velocity of the carrier, at each observation instant, a step of verifying that at each of the observation instants, the short-term evolution of the carrier phase of the signals received on each of the satellite sight axes is consistent with the calculated velocity and a step of verifying that at each of the observation instants, the filtered position obtained on the basis of the long-term filtered measurements of pseudo-distance through the carrier phase is dependable.
1. A method of checking an integrity of an estimation of a position of a mobile carrier, the position being established by a satellite-based positioning measurement system, the estimation being obtained by a real time kinematic (RTK) procedure, the procedure being based on measurements of a first carrier phase of global navigation satellite system (GNSS) signals arising from satellites, the method verifying that a carrier phase measurement is consistent with a code pseudo-distance measurement, wherein the method comprises:
calculating an initial position and an initial time of the carrier, on the basis of pseudo-distances estimated on sight axes of the satellites, based on time measurements received and carried by spreading codes of the signals;
verifying an integrity of a resolution of the initial position and of the initial time, on the basis of satellite pseudo-distances calculated on the basis of a standard algorithm for monitoring satellite faults of receiver autonomous integrity monitoring (RAIM) type;
calculating a velocity of the carrier, at a plurality of observation instants, on the basis of apparent-doppler measurements estimated on the sight axes, on the basis of the first carrier phase measurements;
verifying that, at each of the observation instants, a short-term evolution of a second carrier phase of signals received on each of the sight axes is consistent with the calculated velocity;
verifying that, at each of the observation instants, a filtered position obtained on the basis of long-term filtered measurements of pseudo-distance through the second carrier phase is dependable due to a measurement bias being greater than a phase measurement uncertainty.
2. The method of claim 1 , further comprising:
resolving phase integer ambiguities in an uncertainty domain associated with the filtered position.
3. The method of to claim 1 , further comprising:
calculating the RTK position, on the basis of the first carrier phase measurements; and
verifying a final integrity of the position by (i) applying the standard algorithm to differential phase residuals and (ii) associating a protection radius therewith.