The height approximating precision in combination height meters depends on the variance of the error of evaluating status variables and the variance of the measurement noise. Within concrete flight conditions it is necessary to give a general evaluating criterion for these variances. However, since the properties of combination height meters are different, when we observe status variables of each combination height measurement, we see that the intensities of measurement noise are different. While evaluating the precision of approximating height between combination height meters we need compare evaluations of the observability level of corresponding status variables.
The scheme of the structure of the height measurement for choosing the structure is described in Figure 1.
The scheme of the structure of the height measurement for choosing the structure
Where: H is the practical height information which we need to measure; xk is the error vector of IHM; is the approximating error vector of IHM.
The structure is chosen in accordance with the maximum of the criterion for the observability level of components of the corresponding status vectors of the combination height meters, namely
For each height measurement performed by the linked height meter: the information about each component of the status vector defines the observability level.
In each structure of the linked height meter we perform calculations and define the observability level of status variables.
We compare observability levels of corresponding status variables.