Navigation device, and method for determining a navigation solution

A navigation device, including:

• an inertial measurement unit which generates inertial measurement data;
• a speed measurement system, which emits at least one spatially focused, preferably electromagnetic wave at a predefined frequency and determines a frequency spectrum from a reflection intensity of the wave reflected from a reference object, in particular the earth's surface, wherein a Doppler shift of the predefined frequency allows determining a speed of the navigation device in the direction of emission relative to the reference object;
• and
• an estimation filter, in particular a Kalman filter, which uses the inertial measurement data generated by the inertial measurement unit and the frequency spectrum determined by the speed measurement system as input data in order to determine therefrom a navigation solution by the navigation device, which indicates a previous movement of the navigation device in space, wherein
• the estimation filter calculates an estimated frequency spectrum for a next point in time on the basis of the navigation solution determined based on the input data previously obtained, compares the frequency spectrum actually determined by the speed measurement system at this next point in time with the estimated frequency spectrum, and corrects the navigation solution based on deviations between the estimated and the actually determined frequency spectrums, preferably in such a way that the deviations are reduced.