Threshold value determining method for local enhanced system completeness monitoring

The invention provides a threshold value determining method for local enhanced system completeness monitoring. According to the method, the corresponding quantile is calculated according to the false alarm rate requirements of a local enhanced system; then, a satellite elevation angle interval is divided according to actual use requirements, and in addition, collected observation quantity data are grouped according to the intervals; the average value and the standard difference of each group of data are calculated, and normalization processing is carried out; then, the expansion Gaussian distribution is utilized for enveloping the probability density distribution of the normalization data for thus calculating an expansion factor; the quantile, the average value, the standard value and the expansion factor are used for calculating the threshold value of each interval; finally, the threshold value of each interval is utilized for fitting to obtain a threshold value curve. The threshold value determining method has the advantages that the requirements of the local enhanced system on the false alarm rate are met, and meanwhile, the threshold value is determined by using the data collected by the system per se, so the threshold value determining method better conforms to the actual characteristics of the system.