Method and device for determining availability of ARAIM system

A method for determining the availability of a satellite navigation system of an aerial craft in a flight phase, comprising:

• receiving, by a satellite receiver, measurement data of each satellite of the aerial craft in the flight phase at each time point, the measurement data including a position coordinate and a clock offset of the satellite, and the each time point including a current time point and several time points before the current time point;
• performing, executed by a processor, empirical mode decomposition on the position coordinate and the clock offset respectively, to obtain a position coordinate mode component and a clock offset mode component of each satellite at each time point;
• obtaining, executed by the processor, a position coordinate mode component and a clock offset mode component of each satellite at a time point next to the current time point respectively, according to a preset autoregressive moving average model, a preset random noise sequence parameter, and the position coordinate mode component and the clock offset mode component of each satellite at each time point;
• calculating, executed by the processor, a horizontal protection level (HPL), a vertical protection level (VPL) and an effective monitor threshold (EMT) respectively, according to the position coordinate mode component and the clock offset mode component of each satellite at the time point next to the current time point and preset ground integrity support information;
• and
• comparing, executed by the processor, the HPL, the VPL and the EMT respectively with a preset HPL threshold, a preset VPL threshold, and a preset EMT threshold, to obtain a comparison result comprising a first difference between the HPL and preset HPL threshold, a second difference between the VPL and the preset VPL threshold, and a third difference between the EMT and the preset EMT threshold;
• determining the availability of the satellite navigation system at the current time point and at the time point next to the current time point time when the aerial craft is on a long-distance flight in accordance with the comparison result;
• and
• applying the satellite navigation system to the aerial craft when an integrity requirement for navigation performance needed in the flight phase of an aerial craft is satisfied in accordance with the comparison result and availability.